DESIGN CRil 1
, kEUSE OF RENO
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D A R Y L B . S I M O N S - Y U N G HAI C H E N - L A W R E N C E J . S W E N S O N a n d S I M O N S , L l & A S S O C I A T E S , I N C . P.O. B O X 1 8 1 6 , F O R T C O L L I N S , C O L O R A D O Prepared for
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HYDRAUUC TEST
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- THE USE OF
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HYDRAULIC T E S T TO D E V E L O P D E S I G N C R I T E R I A F O R T H E U S E O F R E N O M A T T R E S S E S E R R A T A P a g e 4.30 F i g u r e 4.21 V e r t i c a l axis s h o u l d read " A z / d m " P a g e A S , L i n e s 6 & 7 Read a s ' • T m = 0.75 V DS" P a g e A 6 P a r a g r a p h ' b ' Read as " F r o m F i g u r e 4 . 2 1 . A m d t # 1 , J a n . 8 5 W i l l i a m s p o r t , MD March, 1984Page LIST OF FIGURES i v LIST OF TABLES v i FORWARD >/1i EXECUTIVE SUMMARY v i i i I . INTRODUCTION 1.1 The Problem 1.1 1.2 O b j e c t i v e s . 1.1 1.3 O r g a n i z a t i o n o f t h e Report 1.2 I I . GABIONS AND MATTRESSES: A LITERATURE REVIEW
2 . 1 I n t r o d u c t i o n 2 . 1 2.2 A p p l i c a t i o n s 2.2 2.3 B e h a v i o r and Design 2.6
I I I . MATTRESS TEST PROGRAM
3 . 1 I n t r o d u c t i o n 3 . 1 3.2 Scale-Model M a t t r e s s T e s t Program 3 . 1
3 . 2 . 1 Test F a c i l i t i e s and T e s t Scales 3 . 1
3 . 2 . 2 I n s t r u m e n t a t i o n 3.13 3 . 2 . 3 T e s t Procedure 3.16 3 . 2 . 4 Test C o n d i t i o n s and Data C o l l e c t e d i n t h e 8 - F o o t
Flume 3.20 3 . 2 . 5 Test C o n d i t i o n s and Data C o l l e c t e d i n t h e 4 - F o o t
Flume 3.28 3.3 F u l l - S i z e M a t t r e s s T e s t Program 3.28 3 . 3 . 1 T e s t F a c i l i t i e s 3.28 3 . 3 . 2 I n s t r u m e n t a t i o n 3.35 3 . 3 . 3 T e s t C o n d i t i o n s 3.37 3 . 3 . 4 Problems P e r t a i n i n g t o F u l l - S c a l e M a t t r e s s T e s t s . . . 3.37 I V . ANALYSIS OF RESULTS 4 . 1 I n t r o d u c t i o n 4 . 1 4 . 2 H y d r a u l i c " ö F M a t t r e s s Channels 4 . 1 4 . 2 . 1 Roughness C o e f f i c i e n t s 4 . 1 4 . 2 . 2 V e l o c i t y D i s t r i b u t i o n 4 . 2 4 . 2 . 3 R e l a t i o n Between Shear S t r e s s and V e l o c i t i e s 4 . 6
4 . 2 . 4 V e l o c i t y a t t h e M a t t r e s s and F i l t e r I n t e r f a c e and
a t t h e F i l t e r and S o i l I n t e r f a c e 4 . 9
4 . 2 . 5 Pressure V a r i a t i o n 4.10
TABLE OF CONTENTS ( c o n t i n u e d )
Page
4 . 3 I n c i p i e n t Motion C o n d i t i o n s 4.12 4 . 4 D e f o r m a t i o n o f t h e M a t t r e s s 4 . 2 1 V. DEVELOPMENT OF DESIGN CRITERIA
5 . 1 Development Approach 5 . 1 5 . 2 D e t e r m i n a t i o n o f H y d r a u l i c C o n d i t i o n s 5 . 1 5.3 D e t e r m i n a t i o n o f M a t t r e s s Requirement Based on I n c i p i e n t Motion C r i t e r i a 5 . 2 5 . 4 D e t e r m i n a t i o n o f V e l o c i t y at t h e M a t t r e s s / F i l t e r ( o r Base S o i l ) I n t e r f a c e 5.3 5.5 D e t e r m i n a t i o n o f F i l t e r Requirement 5.4 5.6 D e t e r m i n a t i o n o f P o t e n t i a l D e f o r m a t i o n 5.6
V I . SUMMARY AND CONCLUSIONS 6 . 1
V I I . REFERENCES 7 . 1
APPENDIX - DE'SIGN EXAMPLES
Page F i g u r e 4 . 6 . Comparison between t h e measured and computed v e l o c i t y
i n t h e m a t t r e s s and f i l t e r i n t e r f a c e 4 . 1 1 F i g u r e 4 . 7 . V a r i a t i o n o f s p e c i f i c head i m m e d i a t e l y below t h e f u l l -s c a l e m a t t r e -s -s e -s 4.13 F i g u r e 4 . 8 . V a r i a t i o n o f s p e c i f i c head i m m e d i a t e l y below t h e f u l l - s c a l e m a t t r e s s e s 4.14 F i g u r e 4 . 9 . C r i t i c a l v e l o c i t y t h a t i n i t i a t e s rock movement as a f u n c t i o n o f rock s i z e 4.16 F i g u r e 4 . 1 0 . C r i t i c a l v e l o c i t y t h a t i n i t i a t e s rock movement as a f u n c t i o n o f m a t t r e s s t h i c k n e s s 4.17
F i g u r e 4 . 1 1 . C r i t i c a l shear s t r e s s versus rock s i z e s f o r t h e w i t h
and w i t h o u t m a t t r e s s cases 4.19 F i g u r e 4 . 1 2 . S h i e l d s parameter as a f u n c t i o n o f t h e shear Reynolds
number f o r w i t h and w i t h o u t m a t t r e s s cases 4.20 F i g u r e 4 . 1 3 . C r i t i c a l shear s t r e s s versus m a t t r e s s t h i c k n e s s 4.22 F i g u r e 4 . 1 4 . General p a t t e r n o f rock movement w i t h i n a m a t t r e s s
compartment 4.23 F i g u r e 4 , 1 5 . Comparison o f d e f o r m a t i o n o f 6 i n c h and 9 i n c h f u l l
-s c a l e m a t t r e -s -s u n i t -s f o r a v e l o c i t y o f 12 f p -s 4,25 F i g u r e 4 . 1 6 . Comparison of d e f o r m a t i o n o f 6 i n c h and 9 i n c h f u l l
-s c a l e m a t t r e -s -s u n i t -s f o r a v e l o c i t y o f 20 f p -s 4.26
F i g u r e 4 . 1 7 . D e f o r m a t i o n o f m a t t r e s s e s ( 9 " ) due t o rock movement
( l o o k i n g downstream). V = 16.4 f p s 4.27 F i g u r e 4 . 1 8 . D e f o r m a t i o n o f m a t t r e s s e s ( 9 " ) due t o rock movement
( l o o k i n g downstream). V = 17.6 f p s 4.27 F i g u r e 4 . 1 9 . 4.28 F i g u r e 4 . 2 0 . 4.29 F i g u r e 4 . 2 1 . R e l a t i o n s h i p between t h e d e f o r m a t i o n f a c t o r and e f f e c t i v e S h i e l d s parameter 4.30 F i g u r e 5 . 1 . P e r m i s s i b l e u n i t t r a c t i v e f o r c e f o r canals i n c o h e s i v e
m a t e r i a l as c o n v e r t e d from t h e U.S.S.R. data on
p e r m i s s i b l e v e l o c i t i e s 5.5
LIST OF FIGURES
Page
F i g u r e 3 . 1 . Scale-model e x p e r i m e n t setup 3.2
F i g u r e 3 . 2 . Plan view o f s c a l e model m a t t r e s s c o n f i g u r a t i o n 3.5 F i g u r e 3 . 3 . Plan view o f scale-model m a t t r e s s c o n f i g u r a t i o n i n
t h e 4 - f o o t flume 3.6 F i g u r e 3 . 4 . Overview o f 8 - f o o t t i l t i n g flume t e s t setup 3.9
F i g u r e 3 . 5 . Overview o f t h e 4 - f o o t t i l t i n g flume t e s t setup 3.10
F i g u r e 3 . 6 . 3.12 F i g u r e 3 . 7 . Pressure t r a n s d u c e r c a l i b r a t i o n r e l a t i o n s h i p 3.15
F i g u r e 3 . 8 . C o n f i g u r a t i o n o f p r e s s u r e i n s t r u m e n t a t i o n 3.17 F i g u r e 3 . 9 . A view o f 4 - f o o t flume run f o r Q = 50 c f s 3.18
F i g u r e 3.10 3.19 F i g u r e 3 . 1 1 . 3.27 F i g u r e 3 . 1 2 . Experimental setup f o r p r o t o t y p e M a c c a f e r r i
M a t t r e s s t e s t s 3.34 F i g u r e 3 . 1 3 . Pressure tap l o c a t i o n diagram f o r t h e 9 i n c h f u l l
-s c a l e m a t t r e -s -s t e -s t -s 3.36 F i g u r e 3 . 1 4 . O v e r a l l view o f o u t d o o r f1ume s e t u p . Q = 80 c f s 3 . 4 1
F i g u r e 3 . 1 5 . View o f flume i n v i c i n i t y below n o z z l e f o r Q = 56 c f s . . . 3.42 F i g u r e 4 . 1 . Comparison between t h e measured and computed
Manning's roughness c o e f f i c i e n t 4 . 3 F i g u r e 4 . 2 . V e l o c i t y d i s t r i b u t i o n f o r s e l e c t e d m o d e l - s c a l e
m a t t r e s s t e s t s i n t h e 4 - f o o t flume 4 . 4 F i g u r e 4 . 3 . Average v e l o c i t y f o r s e l e c t e d m o d e l - s c a l e m a t t r e s s
t e s t s i n t h e 4 - f o o t flume 4.5 F i g u r e 4 . 4 . R e l a t i o n s h i p between shear s t r e s s , v e l o c i t y and
h y d r a u l i c r a d i u s 4.7 d.Q
F i g u r e 4 . 5 . = v s . Froude number ( f r o m F i u z a t , e t a l . 1982) . . . . 4 . 8
Page T a b l e 2 . 1 . Thickness o f Reno M a t t r e s s R e l a t e d t o Water V e l o c i t y . . . 2.10
T a b l e 3 . 1 . M o d e l - t o - P r o t o t y p e S c a l i n g R a t i o s 3.3 T a b l e 3 . 2 . Dimensions o f Model-Scale and F u l l - S c a l e M a t t r e s s e s
T e s t e d 3.4 T a b l e 3 . 3 . Scale-Model M a t t r e s s T e s t Data i n t h e 8 - F o o t Flume . . . . 3.21
T a b l e 3 . 4 . Manning's Roughness C o e f f i c i e n t f o r t h e Model-Scale
M a t t r e s s e s T e s t s Conducted i n t h e 8 - F o o t Flume 3.26
Table 3 . 5 a . Run Sequence f o r T e s t A 6 - I n c h M a t t r e s s 3.2Ö T a b l e 3 . 5 b . Run Sequence f o r T e s t B 9 - I n c h M a t t r e s s 3.30 T a b l e 3 . 5 c . Run Sequence f o r T e s t C 1 2 - I n c h M a t t r e s s 3 . 3 1 Table 3 . 5 d . Run Sequence f o r T e s t D 1 8 - I n c h M a t t r e s s 3.32 Table 3 . 5 e . Run Sequence f o r T e s t E 6 - I n c h M a t t r e s s With M a s t i c . . . . 3.33
T a b l e 3 . 6 . T e s t Run Sequence - D i s c h a r g e , D e p t h , V e l o c i t y Measurements f o r t h e 9 - I n c h F u l l - S c a l e M a t t r e s s T e s t s . . . 3 . 3 8 Table 3 . 7 . D e t e r m i n a t i o n o f 9 - I n c h M a t t r e s s P r o p e r t i e s , Roughness C o e f f i c i e n t , n^^ - Bed Shear S t r e s s , -v^ 3.39 T a b l e 3 . 8 . D e t e r m i n a t i o n o f 9 - I n c h M a t t r e s s P r o p e r t i e s , Roughness C o e f f i c i e n t , n^ - Bed Shear S t r e s s , 3.40 v i
T h i s study was performed under a c o n t r a c t e n t i t l e d " H y d r a u l i c T e s t s t o Develop Design C r i t e r i a f o r t h e Use o f M a t t r e s s e s . " The t e s t s were conducted a t t h e H y d r a u l i c s L a b o r a t o r y , E n g i n e e r i n g Research C e n t e r , Colorado S t a t e U n i v e r s i t y . T h i s r e p o r t i n c l u d e s t h e a n a l y s i s o f data c o l l e c t e d d u r i n g t h e s t u d y and t h e c o n c l u s i o n s drawn a c c o r d i n g l y . The i n v e s t i g a t i o n was conducted by D r . D a r y l B. Simons, P r o f e s s o r o f C i v i l E n g i n e e r i n g , Colorado S t a t e
U n i v e r s i t y , D r . Yung Hai Chen, A s s o c i a t e P r i n c i p a l E n g i n e e r , and Mr. Lawrence J . Swenson, H y d r a u l i c Engineer o f Simons, L i & A s s o c i a t e s , I n c . ( S L A ) . D r . Ruh-Ming L i , P r i n c i p a l H y d r a u l i c Engineer o f SLA, was t h e T e c h n i c a l Reviewer t o r e v i e w the t e s t program and r e s u l t s .
Mr. Alan D. C r o w h u r s t , Dr. Eng. R. A g o s t i n i and Mr. E. A l l e n Dye o f M a c c a f e r r i Gabions, I n c . served as the c o n t r a c t i n g r e p r e s e n t a t i v e s , t e c h n i c a l c o n s u l t a n t and l i a i s o n between SLA and the M a c c a f e r r i S t e e l Wire P r o d u c t s , L t d . D r . Rebecca M. Summer, Mr. Mark R. P e t e r s o n , Mr. James E. Goodman, Mr. Steven R. Townsley and Mr. Michael M u s s e t t e r a s s i s t e d i n c o n d u c t i n g the s t u d y . The study p e r i o d was from May 1982 t o May 1983.
O b j e c t i v e s
V a r i o u s p r o t e c t i o n measures have been developed t o i n s u r e t h e c o n t i n u e d f l o w o f w a t e r a l o n g a p r e s e l e c t e d p a t h and t o s t a b i l i z e channels and s o i l s l o p e s . Gabions and reno m a t t r e s s e s are p r o t e c t i v e d e v i c e s t h a t have been s u c c e s s f u l l y u t i l i z e d t o meet t h e s e needs. G u i d e l i n e s or methodologies c o n -c e r n i n g gabion and reno m a t t r e s s a p p l i -c a t i o n s have been e s t a b l i s h e d p r i m a r i l y t h r o u g h f i e l d e x p e r i e n c e and e m p i r i c a l a n a l y s i s , a i d e d i n some i n s t a n c e s by h y d r a u l i c model s t u d i e s . F u r t h e r r e s e a r c h i s necessary t o generate t h e r e q u i r e d data base from which t o develop d e s i g n c r i t e r i a f o r reno m a t t r e s s a p p l i c a t i o n s .
The p r e s e n t study was aimed a t e v a l u a t i n g t h e performance o f M a c c a f e r r i m a t t r e s s p r o d u c t s when used as r i v e r and canal bank and bed r e v e t m e n t . A h y d r a u l i c t e s t i n g program was developed and u n d e r t a k e n t o p r o v i d e e x p e r i m e n t a l data p e r t a i n i n g t o t h e performance o f reno m a t t r e s s e s . T e s t data were u t i -l i z e d t o deve-lop r e -l i a b -l e design c r i t e r i a f o r M a c c a f e r r i reno m a t t r e s s e s . Major t a s k s i n c l u d e : 1 . To r e v i e w t h e e x i s t i n g d e s i g n m e t h o d o l o g i e s and f i e l d a p p l i c a t i o n e x p e r i e n c e p e r t a i n i n g t o gabions and m a t t r e s s e s . 2 . To determine t h e roughness o f r e v e t m a t t r e s s e s . 3 . To e v a l u a t e r e q u i r e m e n t s o f u n d e r l y i n g g r a n u l a r f i l t e r s or f i l t e r c l o t h l a y e r s . 4 . To e v a l u a t e t h e s t a b i l i t y o f m a t t r e s s e s s u b j e c t e d t o v a r i o u s f l o w c o n d i t i o n s .
5 . To a n a l y z e t e s t r e s u l t s and develop design c r i t e r i a a p p l i c a b l e t o m a t t r e s s p r o t e c t i o n d e s i g n s .
L i t e r a t u r e Review
Gabion and m a t t r e s s e s are r o c k - f i l l e d w i r e d e v i c e s which have been used f o r c o n t r o l l i n g e r o s i o n and s t a b i l i z i n g s o i l s f o r c e n t u r i e s . Gabions o r w i r e -bound rock sausages were i n t r o d u c e d by M a c c a f e r r i i n 1894 t o r e p a i r t h e breach o f t h e R i v e r Reno a t C a s a l e c c h i o . The use o f gabions and m a t t r e s s e s has a number o f advantages. The s t r e n g t h and f l e x i b i l i t y o f t h e s t e e l w i r e mesh a l l o w s t h e r o c k - f i l l e d b a s k e t t o change shape w i t h o u t f a i l u r e due t o u n s t a b l e ground o r scour from moving w a t e r . Gabions and m a t t r e s s e s are permeable and
t h e r e f o r e e l i m i n a t e t h e problems due t o t h e h y d r a u l i c l i f t f o r c e s . A l s o , they p e r m i t p l a n t growth f o r added s t a b i l i t y and t r a p p i n g e f f i c i e n c y . C l i m a t e has no measureable e f f e c t on t h e performance and l o n g e v i t y o f gabions and
m a t t r e s s e s . F i n a l l y , gabions and m a t t r e s s e s are economical t o implement and p r o v i d e a c o s t - e f f e c t i v e means o f s t a b i l i z a t i o n and e r o s i o n c o n t r o l .
M a j o r a p p l i c a t i o n s o f gabions and m a t t r e s s e s i n c l u d i n g t h e f o l l o w i n g : revetments t o p r o t e c t r i v e r embankments a g a i n s t e r o s i o n ; s t a b i l i z a t i o n o f b r i d g e abutments; g r o i n s t o d e f l e c t and " t r a i n " r i v e r c u r r e n t s ; i r r i g a t i o n and s h i p canal l i n i n g s ; check dam, w e i r s and drop s t r u c t u r e s ; c u l v e r t p r o t e c t i o n ; p r o t e c t i v e works t o d i s s i p a t e wave a c t i o n a l o n g c o a s t a l and l a k e s h o r e s ; road s t a b i l i z a t i o n ; s e d i m e n t a t i o n ponds; stream r e h a b i l i t a t i o n ; r e t a i n i n g w a l l s ; and b o a t l a u n c h i n g ramps.
Design c h a r t s f o r p l a c i n g gabion w e i r s on s l o p i n g and h o r i z o n t a l s u r f a c e s were developed by Stephenson ( 1 9 8 0 ) . The c h a r t s and e q u a t i o n s were v e r i f i e d e x p e r i m e n t a l l y t o determine s t r u c t u r a l s t a b i l i t y a g a i n s t s l i d i n g and o v e r -t u r n i n g . Oswald and Maynard (1978) conduc-ted a s e r i e s o f -t e s -t s -t o e v a l u a -t e t h e e f f e c t i v e n e s s o f s e v e r a l schemes u s i n g gabions f o r bank p r o t e c t i o n . No r e s u l t s were s p e c i f i e d . Brown (1979) i n v e s t i g a t e d v a r i o u s t h e o r e t i c a l , e x p e r i -mental and p r o t o t y p e aspects of t h e use o f g a b i o n - t y p e r e v e t m e n t s . Many o t h e r
r e s e a r c h e r s conducted s i t e - s p e c i f i c model s t u d i e s o f t h e use o f gabions f o r bank p r o t e c t i o n o r f o r b r e a k w a t e r . O s w a l t , e t a l . (1975) conducted a
h y d r a u l i c model study a t t h e H y d r a u l i c L a b o r a t o r y o f t h e U.S. Army Engineer Waterways Experiment S t a t i o n t o e v a l u a t e bank p r o t e c t i o n r e q u i r e m e n t s f o r t h e F o u r m i l e Run l o c a l f l o o d - c o n t r o l p r o j e c t . Both t h e r i p r a p and m a t t r e s s e s were t e s t e d i n t h e model. I t was found t h a t i n s e v e r a l reaches i n t h e c h a n n e l , the f l o w c o n d i t i o n s r e s u l t e d i n f a i l u r e o f t h e 3 6 - i n c h r i p r a p w h i l e t h e
12 X 3 X 1 - f o o t m a t t r e s s e s w i t h p r o p e r t o e p r o t e c t i o n would p r o v i d e necessary p r o t e c t i o n . The r e s u l t s o f t h e i r study a l s o i n d i c a t e d t h a t t h e r e q u i r e d m a t t r e s s t h i c k n e s s i s no more than o n e - t h i r d t h e r e q u i r e d r i p r a p t h i c k n e s s . A g o s t i n i and P a p e t t i (1978) recommended t h i c k n e s s o f Reno M a t t r e s s r e l a t e d t o f l o w v e l o c i t i e s and proposed t h e canal s i d e s l o p e s a c c o r d i n g t o s o i l t y p e . They found t h a t compared w i t h t h e use o f r i p r a p a savings o f 25 t o 30 p e r c e n t c o u l d be o b t a i n e d by u s i n g t h e m a t t r e s s e s . C o n s i d e r i n g the a v a i l a b l e i n f o r m a t i o n , i t i s c l e a r t h a t very 1 i m i t e d i n f o r m a t i o n i s a v a i l a b l e r e g a r d i n g t h e performance o f m a t t r e s s e s under h i g h f l o w c o n d i t i o n s . A d d i t i o n a l study i s r e q u i r e d t o answer t h e f o l l o w i n g q u e s t i o n s : i x
2 . What w i l l be the change i n m a t t r e s s performance when t h e f l o w c o n d i t i o n s a r e h i g h e r than t h e c r i t i c a l ( i n c i p i e n t m o t i o n ) c o n d i t i o n s ?
3 . What i s t h e r e q u i r e m e n t o f f i l t e r under h i g h f l o w c o n d i t i o n s ?
The study r e s u l t s p r e s e n t e d i n t h i s r e p o r t w i l l address these q u e s t i o n s .
T e s t Program
To e v a l u a t e m a t t r e s s performance over a range o f c o n d i t i o n s , a t w o -s e c t i o n t e -s t -scheme i n v o l v i n g f u l l - -s c a l e t e -s t -s complemented by -scale-model t e s t s was c o n d u c t e d . H y d r a u l i c t e s t s o f scale-model m a t t r e s s e s were conducted u s i n g t h e e i g h t - f o o t wide flume l o c a t e d i n t h e H y d r a u l i c s L a b o r a t o r y a t t h e Colorado S t a t e U n i v e r s i t y E n g i n e e r i n g Research C e n t e r . T h i s flume i s e i g h t f e e t w i d e , f o u r f e e t deep and 200 f e e t l o n g and can be r a i s e d o r lowered t o produce s l o p e s r a n g i n g from zero t o about two p e r c e n t . A maximum f l o w r a t e o f a p p r o x i m a t e l y 100 c f s can be a c h i e v e d .
Two s e r i e s o f scale-model m a t t r e s s t e s t s were c o n d u c t e d : one u t i l i z e d t h e o r i g i n a l e i g h t - f o o t flume and t h e o t h e r u t i l i z e d t h e f o u r - f o o t flume which was e s t a b l i s h e d by i n s t a l l i n g a 1 0 0 - f o o t l o n g p a r t i t i o n w a l l a t the c e n t e r o f t h e e i g h t - f o o t f l u m e . The m a t t r e s s e s t e s t e d i n t h e f o u r - f o o t flume i n c l u d e d 6 - i n c h , 9 - i n c h , 1 2 - i n c h and 1 8 - i n c h t h i c k rock m a t t r e s s e s and 6 - i n c h t h i c k g r o u t e d m a t t r e s s e s which were c o n v e r t e d t o m o d e l s c a l e u s i n g a m o d e l t o -p r o t o t y -p e l e n g t h r a t i o o f 1 : 3 . Because a v a i l a b l e mesh screen f o r making scalemodel m a t t r e s s e s was l i m i t e d , i t was d i f f i c u l t t o achieve dynamic s i m i -l a r i t y between t h e mode-l mesh and p r o t o t y p e mesh. A t e n s i -l e t e s t conducted by M a c c a f e r r i Gabions i n d i c a t e d t h a t t h e m o d e l - s c a l e mesh u t i l i z e d f o r t h e model t e s t s i n t h e f o u r - f o o t flume was more f l e x i b l e compared t o f u l l - s c a l e ones. The r e s u l t s o b t a i n e d from these model t e s t s would guarantee a s a f e t y c o e f f i c e n t . However, comparison between model and p r o t o t y p e t e s t s r e s u l t s i n d i -c a t e s t h a t t h e i r r e s u l t s are -comparable. The -c h a r a -c t e r i s t i -c s o f s-cale-model m a t t r e s s e s are p r e s e n t e d i n Table 3 . 2 . Only t h e 9 - i n c h m a t t r e s s e s which were c o n v e r t e d t o model s c a l e were t e s t e d i n t h e e i g h t - f o o t f l u m e .
S i x - i n c h and n i n e - i n c h t h i c k f u l l - s c a l e m a t t r e s s e s were t e s t e d i n a
s e v e n - f o o t w i d e , 7 5 - f o o t l o n g and f o u r - f o o t h i g h o u t d o o r flume w i t h a s l o p e o f 13 p e r c e n t . The maximum d i s c h a r g e c a p a c i t y i s 100 c f s . Table 3.2 g i v e s the c h a r a c t e r i s t i c s o f these m a t t r e s s e s .
I n o r d e r t o d e t e r m i n e t h e f l o w c o n d i t i o n s t h a t i n i t i a t e t h e movement o f f i l l i n g rocks w i t h i n t h e m a t t r e s s e s , t h e t e s t c o n d i t i o n s were always s t a r t e d a t r e l a t i v e l y low v e l o c i t y and l a r g e d e p t h . These t e s t v e l o c i t i e s were i n c r e a s e d s t e p by s t e p t o d e t e r m i n e t h e i n c i p i e n t f l o w c o n d i t i o n s . Tables 3 . 3 , 3.5 and 3.6 p r e s e n t t h e t e s t c o n d i t i o n s conducted i n the e i g h t - f o o t i n d o o r f l u m e , t h e f o u r - f o o t i n d o o r flume and t h e s e v e n - f o o t o u t d o o r f l u m e , r e s p e c t i v e l y . The maximum v e l o c i t i e s o b t a i n e d from these t h r e e flumes were a b o u t 10, 1 2 , and 21 f p s . The f o r m e r two v a l u e s c o r r e s p o n d t o p r o t o t y p e v e l o -c i t i e s o f about 17 and 21 f p s , r e s p e -c t i v e l y .
Data c o l l e c t e d f o r each run i n c l u d e d d i s c h a r g e , v e l o c i t y , s t a g e , m a t t r e s s bed e l e v a t i o n , and p r e s s u r e f l u c t u a t i o n s a t thee measuring s t a t i o n s . A t t e m p t s were made t o measure v e l o c i t y and p r e s s u r e a t t h e r o c k / f i l t e r and f i l t e r / s o i l
i n t e r f a c e s because these v e l o c i t i e s would be c o n t r o l f a c t o r s a f f e c t i n g s t a b i -l i t y o f base s o i -l . Some measured i n t e r f a c e v e -l o c i t i e s a -l t h o u g h n o t v e r y c o n c l u s i v e were a n a l y z e d and p r e s e n t e d .
A n a l y s i s o f R e s u l t s
The data c o l l e c t e d i n t h e m o d e l - s c a l e m a t t r e s s and f u l l - s c a l e m a t t r e s s t e s t s were analyzed t o d e t e r m i n e :
1 . H y d r a u l i c s o f channels p r o t e c t e d by m a t t r e s s e s .
2 . I n c i p i e n t m o t i o n c o n d i t i o n s o f f i l 1 i n g rocks w i t h i n m a t t r e s s e s , 3 . D e f o r m a t i o n o f m a t t r e s s e s under h i g h f l o w c o n d i t i o n s .
The h y d r a u l i c v a r i a b l e s c o n s i d e r e d i n t h e a n a l y s i s i n c l u d e : roughness c o e f f i c i e n t s , v e l o c i t y d i s t r i b u t i o n s , r e l a t i o n between shear s t r e s s and v e l o -c i t i e s , v e l o -c i t y a t t h e m a t t r e s s and f i l t e r i n t e r f a -c e and a t t h e f i l t e r and s o i l i n t e r f a c e , and p r e s s u r e v a r i a t i o n . I t was found t h a t t h e bed roughness o f t h e m a t t r e s s s u r f a c e c o u l d be d e t e r m i n e d from t h e Meyer-Peter and M u l l e r ' s roughness e q u a t i o n f o r g r a v e l , and the v e l o c i t y d i s t r i b u t i o n c o u l d be a p p r o x i mated by a l o g v e l o c i t y d i s t r i b u t i o n . T h i s i n d i c a t e s t h a t h y d r a u l i c c o n -d i t i o n s i n a m a t t r e s s channel are s i m i l a r t o t h e c o n -d i t i o n i n a g r a v e l be-d channel and t h e m a t t r e s s mesh w i l l n o t s i g n i f i c a n t l y a f f e c t channel
r o u g h n e s s .
shear s t r e s s i s t h e major f a c t o r t h a t c o n t r o l s t h e s t a b i l i t y o f m a t t r e s s and r i p r a p , f o r a g i v e n v e l o c i t y , as d e p t h i s i n c r e a s e d , s t a b i l i t y w i l l be
i n c r e a s e d due t o t h e r e d u c t i o n i n shear s t r e s s . A s i m i l a r c o n c l u s i o n was o b t a i n e d based on the a n a l y s i s o f p r e s s u r e data c o l l e c t e d i n t h i s study an^ based on t h e r i p r a p t e s t s conducted by F i u z a t , e t a l . ( 1 9 8 2 ) . The study o f F i u z a t , e t a l . i n d i c a t e s t h a t t h e s t a b l e s i z e o f rock i s i n v e r s e l y p r o p o r
-1/2 3 t i o n a l t o D w h i l e i t i s p r o p o r t i o n a l t o V .
Based on t h e m o d e l - s c a l e m a t t r e s s t e s t s i n t h e f o u r - f o o t f l u m e , i t was f o u n d t h a t t h e v e l o c i t y i m m e d i a t e l y underneath t h e m a t t r e s s e s remained somewhat unchanged r e g a r d l e s s o f t h e f l o w c o n d i t i o n s t h e m a t t r e s s e s were sub-j e c t e d t o and t h e t h i c k n e s s o f m a t t r e s s e s . T h i s s i t u a t i o n i s o n l y t r u e when t h e major f l o w d i r e c t i o n i s p a r a l l e l t o t h e m a t t r e s s s u r f a c e . The v e l o c i t y a t t h e m a t t r e s s / f i l t e r i n t e r f a c e c o u l d be a p p r o x i m a t e l y d e t e r m i n e d u s i n g a
M a n n i n g ' s e q u a t i o n by assuming t h a t t h e h y d r a u l i c r a d i u s a p p r o x i m a t e l y
e q u a l l e d o n e - h a l f o f t h e median rock s i z e and assuming a Manning's n o f 0 . 0 2 . A c c o r d i n g t o t h e f u l l - s c a l e 9 - i n c h m a t t r e s s t e s t s , t h e v e l o c i t y underneath the f i l t e r f a b r i c a t t h e f i l t e r and s o i l i n t e r f a c e would be about o n e - f o u r t h t o o n e - h a l f o f t h e v e l o c i t y i m m e d i a t e l y above t h e f i l t e r f a b r i c . T h i s v e l o c i t y c o u l d be s u f f i c i e n t l y l a r g e t o move base m a t e r i a l even though t h e m a t t r e s s s t r u c t u r e remained s t a b l e . I n t h i s c a s e , a g r a v e l f i l t e r l a y e r t h a t can e f f e c t i v e l y reduce v e l o c i t y may be a b e t t e r way t o p r o t e c t the base m a t e r i a l .
The a b i l i t y o f t h e m a t t r e s s t o r e s i s t movement by t h e c u r r e n t r e l i e s on i t s m o n o l i t h i c c o n t i n u i t y t o r e s i s t d i s p l a c e m e n t and n o t i t s mass. The rocks i n s i d e t h e m a t t r e s s are r e t a i n e d by t h e w i r e n e t t i n g . I n g e n e r a l , when t h e v e l o c i t y and shear s t r e s s reach a c r i t i c a l m a g n i t u d e , t h e r o c k s i n s i d e t h e m a t t r e s s s t a r t t o move i n t h e main f l o w d i r e c t i o n . The m a t t r e s s t e s t r e s u l t s c l e a r l y i n d i c a t e t h a t m a t t r e s s mesh improves the s t a b i l i t y o f f i l l i n g rocks by d o u b l i n g t h e c r i t i c a l shear s t r e s s compared t o t h a t f o r t h e r i p r a p a l o n e . The S h i e l d s parameter 0,10 f o r t h e m a t t r e s s w h i l e = 0.047 f o r t h e
r i p r a p . These r e s u l t s show t h a t t h e m a t t r e s s i s more s t a b l e t h a n r i p r a p s t r u c t u r e s o f g r e a t e r t h i c k n e s s i f t h e m a t t r e s s s t r u c t u r e i s p r o p e r l y d e s i g n e d and i n s t a l l e d .
With f u r t h e r i n c r e a s e i n f l o w v e l o c i t y and shear s t r e s s beyond t h e c r i t i -c a l v a l u e s , a s i g n i f i -c a n t amount o f ro-cks would move from t h e upstream p o r t i o n o f a m a t t r e s s compartment t o i t s downstream p o r t i o n . T h i s r e s u l t e d i n r e d u c -t i o n s I n -t h i c k n e s s o f rock i n -t h e upper p o r -t i o n o f a m a -t -t r e s s compar-tmen-t and I n c r e a s e i n t h i c k n e s s o f rock i n t h e l o w e r p o r t i o n o f t h e compartment. A d e f o r m a t i o n f a c t o r i s t h e r e f o r e d e f i n e d as t h e r a t i o o f t h e h e i g h t d i f f e r e n c e between t h e l o w e s t and h i g h e s t rock s u r f a c e w i t h i n a m a t t r e s s compartment t o t h e median s i z e o f t h e f i l l i n g r o c k . T h i s r a t i o was r e l a t e d t o t h e e f f e c t i v e S h i e l d s parameter. T h i s r e l a t i o n can be u t i l i z e d t o d e t e r m i n e t h e m a t t r e s s d e f o r m a t i o n as a f u n c t i o n o f h y d r a u l i c c o n d i t i o n s and m a t t r e s s s t r e n g t h .
Based on t h e f u l l - s c a l e m a t t r e s s t e s t s , t h e m a t t r e s s d e f o r m a t i o n would .not s i g n i f i c a n t l y a f f e c t t h e s p e c i f i c head v a r i a t i o n underneath t h e m a t t r e s s
u n l e s s t h e e x t e n t o f rock movement w i t h i n t h e m a t t r e s s was such t h a t t h e f i l t e r o r base m a t e r i a l s were exposed. T h i s i n d i c a t e s t h a t t h e m a t t r e s s even a f t e r d e f o r m a t i o n p r o v i d e d a s i m i l a r degree o f p r o t e c t i o n t o t h a t p r o v i d e d by an undeformed m a t t r e s s i f t h e reduced rock t h i c k n e s s s e c t i o n was more than one median s i z e t h i c k . N i n e i n c h m a t t r e s s e s were found t o be e f f e c t i v e i n p r o -t e c -t i n g s o i l s I n a m i l d s l o p e channel bed under a v e l o c i -t y up -t o 20 f p s . However, g r a v e l f i l t e r s o r a combined g e o t e x t i l e / g r a v e l f i l t e r s h o u l d be u t i l -i z e d t o reduce t h e w a t e r v e l o c -i t y a t t h e m a t t r e s s / f 1 1 t e r -i n t e r f a c e t h a t a t t a c k s t h e base m a t e r i a l s , i f t h i s I n t e r f a c e v e l o c i t y i s s u f f i c i e n t l y h i g h t o a f f e c t t h e s t a b i l i t y o f base s o i l . A d d i t i o n a l s t u d i e s s h o u l d be conducted t o e v a l u a t e t h e e f f e c t i v e n e s s o f v a r i o u s f i l t e r d e s i g n s t o improve the a b l l I t y o f m a t t r e s s e s t o s t a b i l i z e channels under e x t r e m e l y h i g h f l o w c o n d i t i o n s . Development o f Design C r i t e r i a
The f o l l o w i n g steps are proposed t o design t h e m a t t r e s s p r o t e c t i o n w o r k s : 1 . Determine t h e h y d r a u l i c c o n d i t i o n s i n t h e m a t t r e s s channel f o r a g i v e n d e s i g n d i s c h a r g e . 2 . Determine t h e m a t t r e s s r e q u i r e m e n t based on i n c i p i e n t m o t i o n c r i t e r i a . 3 . Determine t h e v e l o c i t y a t t h e m a t t r e s s / f i l t e r ( o r base s o i l s ) i n t e r f a c e . 4 . Determine f i l t e r r e q u i r e m e n t t o s a f e l y p r o t e c t base m a t e r i a l . 5. Determine p o t e n t i a l d e f o r m a t i o n o f m a t t r e s s when f l o w d i s c h a r g e i s l a r g e r t h a n the design d i s c h a r g e . x i i i
t h e m a t t r e s s t e s t s were conducted on f l u m e beds. The developed c r i t e r i a f o r p r o t e c t i n g banks were based on t h e o r i e s and some e m p i r i c a l e q u a t i o n s and s h o u l d be v e r i f i e d whenever p o s s i b l e .
I . INTRODUCTION 1.1 The Problem
V a r i o u s p r o t e c t i o n measures have been developed t o i n s u r e t h e c o n t i n u e d f l o w o f w a t e r a l o n g a p r e s e l e c t e d p a t h and t o s t a b i l i z e channels and s o i l s l o p e s . I n c a n a l s o r c h a n n e l i z e d w a t e r courses p r o t e c t i o n measures t y p i c a l l y embody some t y p e o f channel l i n i n g . A channel l i n i n g p e r m i t s d e s i g n i n g f o r a l a r g e r p e r m i s s i b l e v e l o c i t y o r t r a c i v e f o r c e , w i t h o u t channel scour o r e r o -s i o n , t h a n would be p o -s -s i b l e i n an u n l i n e d c h a n n e l . A d d i t i o n a l l y , l i n i n g -s can be used t o reduce or e l i m i n a t e seepage problems i n c h a n n e l s . Gabions and reno m a t t r e s s e s are p r o t e c t i v e d e v i c e s t h a t have been s u c c e s s f u l l y u t i l i z e d t o meet t h e s e needs.
G u i d e l i n e s o r m e t h o d o l o g i e s c o n c e r n i n g gabion and reno m a t t r e s s a p p l i c a -t i o n s have been e s -t a b l i s h e d p r i m a r i l y -t h r o u g h f i e l d e x p e r i e n c e and e m p i r i c a l a n a l y s i s , a i d e d i n some I n s t a n c e s by h y d r a u l i c model s t u d i e s . F u r t h e r
r e s e a r c h i s necessary t o g e n e r a t e t h e r e q u i r e d data base from which t o develop d e s i g n c r i t e r i a f o r reno m a t t r e s s a p p l i c a t i o n s . Such c r i t e r i a a r e r e q u i r e d t o ensure adequate performance o f reno m a t t r e s s e s under s p e c i f i c h y d r a u l i c and g e o m e t r i c c o n d i t i o n s .
To address these needs, Simons, L i ^< A s s o c i a t e s , I n c . (SLA) was awarded a r e s e a r c h c o n t r a c t by M a c c a f e r r i S t e e l Wire P r o d u c t s , L t d . t o conduct h y d r a u l i c t e s t s o f M a c c a f e r r i Heavy Duty Reno M a t t r e s s e s , and t o develop d e s i g n c r i -t e r i a g o v e r n i n g u -t i l i z a -t i o n o f -these d e v i c e s f o r channel s -t a b i l i z a -t i o n .
1.2 O b j e c t i v e s
The p r e s e n t s t u d y was aimed a t e v a l u a t i n g the performance o f M a c c a f e r r i m a t t r e s s p r o d u c t s when used as r i v e r and canal bank and bed r e v e t m e n t . A h y d r a u l i c t e s t i n g program was developed and undertaken t o p r o v i d e e x p e r i m e n t a l d a t a p e r t a i n i n g t o t h e performance o f reno m a t t r e s s e s . T e s t data were u t i -l i z e d t o deve-lop r e -l i a b -l e design c r i t e r i a f o r M a c c a f e r r i reno m a t t r e s s e s . M a j o r t a s k s d e f i n e d i n t h e study program a r e : 1 To r e v i e w t h e e x i s t i n g d e s i g n m e t h o d o l o g i e s and f i e l d a p p l i c a t i o n e x p e r i e n c e s p e r t a i n i n g t o gabions and m a t t r e s s e s . 2 . To d e t e r m i n e t h e roughness o f r e v e t m a t t r e s s e s . 3 . To e v a l u a t e r e q u i r e m e n t s o f u n d e r l y i n g g r a n u l a r f i l t e r s o r f i l t e r c l o t h 1 a y e r s .
1.2
4 . To e v a l u a t e t h e s t a b i l i t y o f m a t t r e s s e s s u b j e c t e d t o v a r i o u s f l o w c o n d i t i o n s .
5 . To analyze t e s t r e s u l t s and develop d e s i g n c r i t e r i a a p p l i c a b l e t o m a t t r e s s p r o t e c t i o n d e s i g n s .
1.3 O r g a n i z a t i o n o f t h e Report
Chapter I I p r e s e n t s a 1 i t e r a t u r e r e v i e w o f gabion and m a t t r e s s a p p l 1 c a -t l o n s and d i s c u s s -t h e i r a p p l i c a b i l I -t i e s . Chap-ter I I I d e s c r i b e s -t h e l a b o r a -t o r y f a c i l i t i e s , procedures and t e s t c o n d i t i o n s t h a t were a p p l l e d t o e v a l u a t e the performance o f m a t t r e s s e s . Chapter IV p r e s e n t s t h e a n a l y s i s r e s u l t s . A d e s i g n method was developed based on t h e a n a l y s i s r e s u l t s and h y d r a u l i c t h e o r i e s . Chapter V p r e s e n t s t h i s d e s i g n method. Chapter VI summarizes t h e s t u d y program, p r e s e n t s t h e c o n c l u s i o n s and recommends a d d i t i o n a l s t u d i e s . Two examples o f a p p l y i n g t h e developed d e s i g n procedures t o d e s i g n m a t t r e s s p r o t e c t i o n works are p r e s e n t e d i n t h e Appendix.
I I . GABIONS AND MATTRESSES: A LITERATURE REVIEW 2 . 1 I n t r o d u c t i o n
Gabions and m a t t r e s s e s are r o c k - f i l l e d w i r e d e v i c e s which have been used f o r c o n t r o l l i n g e r o s i o n and s t a b i l i z i n g s o i l s f o r c e n t u r i e s . Gabions o r w i r e -bound rock sausages were I n t r o d u c e d by M a c c a f e r r i I n 1894 t o r e p a i r t h e breach o f t h e R i v e r Reno a t C a s a l e c c h i o . Keutner (1935) p r e s e n t e d t h e r e s u l t s o f an e x h a u s t i v e i n v e s t i g a t i o n o f t h e a p p l i c a t i o n s o f gabions I n Germany and
A u s t r i a . The N a t i o n a l Park S e r v i c e i n t h e U n i t e d S t a t e s used gabion t r a i n i n g w a l l s as e a r l y as 1935 ( P a r k e r and K i t t r e d g e , 1935) t o c o u n t e r a c t streambed
e r o s i o n and t h e Highway Commission i n C a l i f o r n i a (1922) employed gabions as a stream bank p r o t e c t i o n measure. Modernized v e r s i o n s o f gabions and m a t t r e s s e s c o n s i s t o f r e c t a n g u l a r compartmented c o n t a i n e r s made o f t h i c k s t e e l w i r e mesh, woven w i t h a t r i p l e t w i s t a t i n t e r s e c t i o n s . Heavy w i r e i s sometimes added or woven i n t o t h e mesh b e f o r e or a f t e r f i l l i n g t o i n c r e a s e i t s s t a b i l i t y and d u r a b i l i t y . The w i r e mesh can be g a l v a n i z e d and c o a t e d w i t h PVC i f used under h i g h l y c o r r o s i v e c o n d i t i o n s . The w i r e baskets can be c o n s t r u c t e d i n t o v a r i o u s g e o m e t r i c shapes. For example, a hexagonal c o n f i g u r a t i o n 1s designed t o c o n -f o r m -f i r m l y t o uneven s u r -f a c e s y e t s t i l l m a i n t a i n I t s I n t e g r i t y s t r u c t u r a l l y .
The use o f gabions and m a t t r e s s e s as n a t u r a l b u i l d i n g b l o c k s and e r o s i o n c o n t r o l has a number o f advantages. The s t r e n g t h and f l e x i b i l i t y o f t h e s t e e l w i r e mesh a l l o w s t h e r o c k - f i l l e d b a s k e t t o change shape w i t h o u t f a i l u r e due t o u n s t a b l e ground o r scour from moving w a t e r . Gabions and m a t t r e s s e s are p e r -meable and t h e r e f o r e e l i m i n a t e t h e problems due t o t h e h y d r a u l i c l i f t f o r c e s . Al so t h e y p e r m i t p l a n t growth f o r added s t a b i l i t y and t r a p p i n g e f f i c i e n c y . C l i m a t e has no measureable e f f e c t on t h e performance and l o n g e v i t y o f gabions and m a t t r e s s e s . F i n a l l y , gabions and m a t t r e s s e s are economical t o implement and p r o v i d e a c o s t e f f e c t i v e means o f s t a b i 1 i z a t i o n and e r o s i o n c o n t r o l .
Gabions and m a t t r e s s e s are s u p p l l e d t o t h e j o b s i t e as f o l d e d mesh and t i e d i n p a i r s . They are u n f o l d e d , p l a c e d i n p o s i t i o n l i k e b r i c k , t i e d t o g e t h e r , and f i l l e d w i t h d u r a b l e r o c k . The mesh c o n t a i n e r s can a l s o be f i l l e d f i r s t and p l a c e d by hand o r by a crane t o areas d i f f i c u l t t o a c c e s s , e g . , u n d e r w a t e r .
M a j o r a p p l i c a t i o n s o f gabions and m a t t r e s s e s i n c l u d e t h e f o l l o w i n g : r e v e t m e n t s t o p r o t e c t r i v e r embankments a g a i n s t e r o s i o n ; s t a b i l i z a t i o n o f b r i d g e a b u t m e n t s ; g r o i n s t o d e f l e c t and " t r a i n " r i v e r c u r r e n t s ; i r r i g a t i o n and s h i p canal 1 i n i n g s ; check dams, w e i r s , and drop s t r u c t u r e s ; c u l v e r t p r o t e c
-2.2
t i o n ; p r o t e c t i v e works t o d i s s i p a t e wave a c t i o n a l o n g c o a s t a l and l a k e shores and b o a t l a u n c h i n g ramps. Gabions are a l s o u t i l i z e d f o r c o n s t r u c t i n g
r e t a i n i n g w a l l s on steep u n s t a b l e s l o p e s , check dams, w e i r s and drop s t r u c t u r e s .
Due t o t h e v a r i e t y o f gabion a p p l i c a t i o n s , s t u d i e s o f gabion performance have n e c e s s a r i l y encompassed many a r e a s . General a p p l i c a t i o n s and s p e c i f i s uses are d i s c u s s e d below t o i l l u s t r a t e t h e v e r s a t i l i t y o f t h i s s t r u c t u r e . F o l l o w i n g t h i s , r e s u l t s o f experiments and t e s t s f o c u s i n g on d i f f e r e n t aspects o f gabion b e h a v i o r are g i v e n . Data are i n c l u d e d where a v a i l a b l e .
2.2 Appl1 c a t i o n s
Gabions have been s t u d i e d and used t o serve a v a r i e t y o f purposes i n t h e p a s t . Many p r o j e c t s and s t u d i e s have been done which d e s c r i b e t h e i r a p p l i c a -t i o n s and u -t i l i -t y as d i s c u s s e d b e l o w .
F i r s t , Roth ( 1 9 7 7 ) , V e l u t e t a l . , ( 1 9 7 7 ) , S c h u s t e r ( 1 9 7 4 ) , Stephenson ( 1 9 7 9 ) , F o r e s t S e r v i c e ( 1 9 7 9 ) , and Burroughs (1979) r e v i e w e d a p p l i c a t i o n s , g e n e r a l d e s i g n s , general i m p l e m e n t a t i o n and case s t u d i e s o f gabion s t r u c t u r e s . Stephenson emphasized t h a t t h e i r p r o p e r t i e s are s u i t a b l e i n energy d i s s i p a t i o n works p a r t i c u l a r l y i n h y d r a u l i c e n g i n e e r i n g . The F o r e s t S e r v i c e (1979) has p u b l i s h e d a r e p o r t based on a workshop which i n c l u d e d general g e o t e c h n i c a l i n v e s t i g a t i o n s o f g a b i o n s .
S e c o n d l y , gabions are used t o s t a b i l i z e low volume economical roads ( T r a n s p o r t a t i o n Research B o a r d , 1 9 7 9 ) . D e t a i l s o f a method f o r u s i n g gabions on low w a t e r c r o s s i n g s f o r p r i m i t i v e o r secondary f o r e s t roads are g i v e n by Leydecker (1973) and d i s c u s s e d i n t h e n e x t s e c t i o n .
Gabions have been i n c l u d e d i n t h e development o f an i n n o v a t i v e s u b s t r u c -t u r a l sys-tem f o r s h o r -t span highway b r i d g e s . GangaRao (1978) found -t h a -t
gabions were one o f t h e s t r u c t u r e s b e s t s u i t e d f o r s u b s t r u c t u r e s on t h e b r i d g e d e s i g n from t h e i n d u s t r i a l i z e d c o n s t r u c t i o n v i e w p o i n t . Ten d i f f e r e n t systems were a n a l y z e d i n d e t a i l w i t h a view t o w a r d ease o f e r e c t i o n , economy, m a i n
-t e n a n c e , l o n g e v i -t y , e f f i c i e n c y , v e r s a -t i l i -t y , e -t c . R e i n f o r c e d e a r -t h , g a b i o n s , segmental p l a n k , e e l l u l a r box, s t e e l b e n t , d r i v e n s t e e l p i l e b e n t , c o n c r e t e b e n t , s t u b system, c o n c r e t e and t i m b e r c r i b b i n g were c o n s i d e r e d t o be r e a s o -n a b l e s t r u c t u r e s f o r s h o r t - s p a -n b r i d g e a b u t m e -n t s . Depe-ndi-ng upo-n t h e m e r i t s and d e m e r i t s , g a b i o n s , c o n c r e t e b e n t , c e l l u l a r box, segmental p l a n k and t i m b e r c r i b b i n g appeared t o be b e s t s u i t e d from t h e I n d u s t r i a l i z e d c o n s t r u c t i o n
Webster and Watkins (1977) I n v e s t i g a t e d t h e f e a s i b i l i t y o f commercial w i r e g a b i o n s , among o t h e r t e c h n i q u e s , f o r c o n s t r u c t i n g b r i d g e approach roads a c r o s s s o f t g r o u n d . The t e s t s e c t i o n was on a s o f t - c l a y subgrade and t r a f f i c l o a d s were on 5 - t o n t r u c k s . The 1 - f o o t gabions were f i l l e d w i t h 3 t o 7 i n c h rock and covered w i t h 2 inches o f crushed s t o n e . The performance o f t h i s s t r u c t u r e was c o n s i d e r e d t o be e x t r e m e l y good.
One o f the approaches t o s o l v i n g highway l a n d s l i d e problems i n Tennessee was t o use g a b i o n s . Royster (1975) d i s c u s s e s v a r i o u s geotechniques used i n c o m b i n a t i o n w i t h gabions t o m i t i g a t e s t a b i l i t y problems i n t h e Smokey
M o u n t a i n s . The s t e e l - m e s h w i r e baskets f i l l e d w i t h heavy rock are t h e key elements i n r e p a i r i n g massive s l i d e s and are used i n p l a c e o f sheet p i l i n g , masonry c o n s t r u c t i o n or c o n c r e t e c r i b b i n g .
Streambank s t a b i l i z a t i o n and r i v e r t r a i n i n g are some o f t h e more common a p p l i c a t i o n s o f gabions and m a t t r e s s e s , e . g . , Gotz (1978) i n Germany, Keown e t a l . , (1977) i n t h e U n i t e d S t a t e s , P e r n i e r (1977) and Michel (1977) i n F r a n c e , and a s t u d y i n Columbia ("Checking R i v e r E r o s i o n i n C o l u m b i a , " 1 9 7 3 ) . I n a d d i t i o n , i t i s c o n s i d e r e d t o be a n a t u r a l and r e l a t i v e l y u n o b t r u s i v e t e c h -n i q u e f o r s t a b i l i z i -n g streambeds i -n -new tow-n developme-nts (Holema-n a-nd Sauer, 1 9 6 9 ) .
Gabions and m a t t r e s s e s have a l s o been used e x t e n s i v e l y f o r r e v e t i n g c a n a l s and c a n a l i s e d w a t e r c o u r s e s , e . g . , i r r i g a t i o n . O s w a l t , e t a l . (1975) compared t h e e f f e c t i v e n e s s o f u t i l i z i n g r i p r a p and m a t t r e s s e s f o r bank p r o t e c -t i o n o f -t h e F o u r m i l e Run l o c a l f l o o d - c o n -t r o l p r o j e c -t . A g o s -t i n i and P a p e -t -t i
(1978) d e s c r i b e d t h e dimensions o f t r a p e z o i d a l channel s e c t i o n s and a p p l i e d l i n i n g s formed w i t h gabions and m a t t r e s s e s .
The use o f gabions as sediment d e t e n t i o n d e v i c e s has been s t u d i e d by Tan and T h i r u m u r t h i (1978) i n Canada and by Poche and Sherwood ( 1 9 7 6 ) . These s t u -d i e s i n -d i c a t e t h a t the f i l t e r i n g c a p a c i t y o f gabions I s l i m i t e -d t o be-dloa-d m a t e r i a l . Poche and Sherwood d e t e r m i n e d the sediment t r a p p i n g e f f i c i e n c y o f s t r a w f i l t e r b a r r i e r s and g a b i o n s . A flume was designed and b u i l t f o r t h e l a b o r a t o r y p o r t i o n o f the study and 21 b a l e s were t e s t e d . T r a p p i n g e f f i c i e n -c i e s v a r i e d from 46 t o 88 p e r -c e n t ; t h e o v e r a l l average was 68 p e r -c e n t . No s i g n i f i c a n t d i f f e r e n c e s were n o t e d i n t h e e f f i c i e n c i e s o f straw and hay, and t h e b u l k d e n s i t y and p o r o s i t y o f t h e b a l e s c o r r e l a t e d p o o r l y w i t h t h e t r a p p i n g e f f i c i e n c i e s . F i e l d o b s e r v a t i o n s o f c o n t r a c t o r - p l a c e d b a l e b a r r i e r s showed a h i g h p e r c e n t a g e o f f a i l u r e s . Most f a i l u r e s were due t o u n d e r c u t t i n g , end
2 . 4
f l o w , and w a s h o u t s . E x p e r i m e n t a l f i e l d b a r r i e r s w i t h numbers and p o s i t i o n s based on t h e u n i v e r s a l s o i l l o s s e q u a t i o n were i n s t a l l e d i n p l a c e o f t h e unmo-d i f i e unmo-d b a r r i e r s . To m i n i m i z e b a r r i e r f a i l u r e s , l o o s e s t r a w was weunmo-dgeunmo-d ununmo-der and between t h e b a l e s making up t h e b a r r i e r ; t h e b a r r i e r l e n g t h was extended so t h a t t h e bottoms o f t h e end b a l e s were h i g h e r t h a n t h e top o f t h e l o w e s t m i d d l e b a l e ; and l o o s e s t r a w was s c a t t e r e d b e h i n d each b a r r i e r . T r a p p i n g e f f i c i e n c i e s a p p r o x i m a t i n g l a b o r a t o r y e f f i c i e n c i e s were o b t a i n e d w i t h t h e e x p e r i m e n t a l b a r r i e r s . Gabions f i l l e d w i t h crushed stone y i e l d e d s i g n i f i
-c a n t l y l o w e r t r a p p i n g e f f i -c i e n -c i e s t h a n t h a t o f s t r a w and hay b a l e s . However, a l a y e r o f straw a t t h e bottom o f t h e gabion i n c r e a s e d t h e e f f i c i e n c y t o
l e v e l s comparable t o t h o s e o f s t r a w b a l e s .
C o a s t a l e n g i n e e r i n g has u t i l i z e d gabions and m a t t r e s s e s i n designs o f shore p r o t e c t i o n s t r u c t u r e s . An a n n o t a t e d b i b l i o g r a p h y o f t h e development o f g r o y n e s , i n c l u d i n g gabion c o n s t r u c t i o n i s g i v e n i n Bal s i l l i e and Bruno ( 1 9 7 2 ) . Chishom (1976) d e s c r i b e d t h e use o f gabions as secondary p r o t e c t i o n a l o n g t h e sea c o a s t o f New Z e a l a n d .
A s i m i l a r a p p l i c a t i o n was implemented on t h e Lake Huron shore ( Q u i g l e y , e t a l . , 1 9 7 4 ) . A system o f t h r e e gabion groynes were s e t up t o p r o t e c t a 122 m l o n g s e c t i o n o f c o a s t a l r e a d y s u b j e c t t o severe e a r t h movements. I n t h e absence o f adequate design i n f o r m a t i o n , t h e d e s i g n was based on p r e l i m i n a r y w i n d data and f i e l d o b s e r v a t i o n s o f beach c h a r a c t e r i s t i c s , sand a v a i l a b i l i t y and p r o b a b l e wave h e i g h t s . The groynes were spaced about 36 m a p a r t and e x t e n d e d o f f - s h o r e from t h e c l i f f t o e f o r a d i s t a n c e o f about 18 m. The ends o f t h e g r o i n e s , t h e r e f o r e , extended t o t h e plunge p o i n t o f 1.2 m h i g h waves g e n e r a t e d by s t r o n g t r a d e winds and about 6Ü p e r c e n t o f t h e d i s t a n c e t o t h e e s t i m a t e d l o c a t i o n o f t h e plunge p o i n t o f severe s t o r m s . The beach h e i g h t a t t h e c l i f f t o e has b u i l t i t s e l f up t o 1.8 m above p r e s e n t w a t e r l e v e l s and p r o -v i d e s a beach berm j u s t adequate t o s t a b i l i z e t h e l o w e r p o r t i o n s o f t h e f a i l i n g c l i f f b e h i n d i t d u r i n g t h e wet s p r i n g c o n d i t i o n s o f 1974. The i n s t a l l a t i o n has been v e r y s u c c e s s f u l , and t h e g r o i n e s have r a p i d l y f i l l e d w i t h sand and g r a v e l .
A n o t h e r p r a c t i c a l use o f gabions and m a t t r e s s e s i s f o r s t a b i l i z i n g l a k e shores and s t o r m w a t e r catchments i n urban a r e a s . A p r o j e c t d e s c r i b e d i n Ground E n g i n e e r i n g Magazine (1976) regarded t h a t i n t h e U n i t e d Kingdom, banks o f a l a k e were s t a b i l i z e d by t h e use o f gabions p l a c e d over 0.5 mm t h i c k
F i b e r t e x f i l t e r sheet (a non-woven m a t e r i a l o f 95 p e r c e n t p o l y p r o p y l e n e ) . A one meter square gabion was sunk onto t h e bottom o f t h e l a k e t o form a
b u t t r e s s f r o m b e h i n d which F i b e r t e x was a n c h o r e d . The F i b e r t e x was then r o l l e d up onto t h e p r o f i l e o f t h e bank and c o v e r e d w i t h a 170 m deep gabion m a t t r e s s f i l l e d w i t h 50-102 mm l i m e s t o n e r u b b l e .
Gabion i n s t a l l a t i o n s have been used i n e x p e r i m e n t s t o i m p r o v e , enhance, and m o d i f y stream f i s h e r i e s and r e h a b i l i t a t e c h a n n e l i z e d s t r e a m s . T h e i r r e l a -t i v e e f f e c -t i v e n e s s and impac-t on -t h e b i o l o g y and c h e m i s -t r y o f a s-tream has been v a r i a b l e a c c o r d i n g t o s t u d i e s by Maughan and Nelson ( 1 9 8 0 ) , Cooper and Wesche (1976) B r a d t and Wieland '(1978) and B a r t o n and Winger ( 1 9 7 3 ) . An example o f an e f f e c t i v e use which p r o v i d e d a means o f p r e v e n t i n g young salmon f r o m m i g r a t i n g t o t h e sea was d e s c r i b e d by McSwain and Schmidt ( 1 9 7 6 ) . The gabions which were made o f heavy t r i p l e t w i s t e d w i r e were shipped f l a t , f i l l e d w i t h 6" minimum s i z e c o b b l e s , and t i e d on t h e j o b s i t e . I n a d d i t i o n t o t h e g a b i o n s , a p e r f o r a t e d s t e e l p i p e , a metal s l i d e gate w i t h c o n c r e t e h e a d w a l l , an emergency f l o w w e i r box, and n a t u r a l stream g r a v e l and c o b b l e s were used t o develop 6 d i f f e r e n t d i v e r s i o n s t r u c t u r e s . T h e i r c o n s t r u c t i o n i s d e s c r i b e d b e l o w .
A gabion dam I s c o n s t r u c t e d as near t h e canal head as i s p r a c t i c a l . P e r f o r a t e d p i p e ( 3 6 " ) encased o r surrounded by r i v e r run g r a v e l i s p l a c e d t h r o u g h t h e dam and extended upstream i n t h e r i v e r bed a t an e l e v a t i o n where i t can be covered w i t h about 7" o f g r a v e l . Thus a l 1 t h e w a t e r t o t h e canal comes t h r o u g h t h e g r a v e l p i p e p e r f o r a t i o n s and t h e gabion dam. As an
emergency w a t e r supply f e a t u r e , a w e i r box w i t h removable f l a s h boards i s i n s t a l l e d i n t h e dam so t h a t t h e g r a v e l , p e r f o r a t i o n s o r dam i n t e r s t i c e s do n o t c l o g . A few f e e t downstream, a metal s l i d e gate on a c o n c r e t e headwal1 i s p r o v i d e d f o r p o s i t i v e f l o w r e g u l a t i o n .
Gabion s t r u c t u r e s were I n c l u d e d i n a s t u d y o f b a r r i e r s which reduce n o i s e l e v e l s . Harmelink and Hajek (1973) conducted f i e l d e v a l u a t i o n o f f i v e b a r r i e r t y p e s : e a r t h embankment, normal d e n s i t y and 1 i g h t w e i g h t p r e - c a s t c o n c r e t e panal w a l l s , aluminum w a l l s , plywood w a l l s and a gabion w a l l . R e s u l t s I n d i -c a t e d t h a t t h e y are r e l a t i v e l y I n e f f e -c t i v e i n r e d u -c i n g freeway t r a f f i -c sound l e v e l s . For example, t h e b a r r i e r s , l o c a t e d midway between t h e houses and t h e pavement o r a t t h e highway s h o u l d e r , 60 f t . - 140 f t . (18m-43m) from t h e n e a r e s t houses, p r o v i d e d o n l y 2-6 dba r e d u c t i o n a t t h e f i r s t row o f houses, 4 f t . (1.2m) above g r o u n d . Immediately b e h i n d t h e b a r r i e r s , where t h e r e d u c -t i o n s a r e o f 1 i -t -t l e r e a l b e n e f i -t , r e d u c -t i o n s o f 8 dba - 14 dba were a c h i e v e d .
2 . 6
2.3 B e h a v i o r and Design
A v a r i e t y o f s t u d i e s have been conducted t o t e s t t h e b e h a v i o r o f gabion s t r u c t u r e s and develop design methods. Several e x p e r i m e n t a l s t u d i e s and d e s i g n procedures are r e v i e w e d b e l o w .
Lavagnino (1974) d e s c r i b e d t h e c o n s t r u c t i o n o f m o d i f i e d r e v e t m e n t o f monol i t h i c gabions which proved t o be an e f f e c t i v e s o l u t i o n t o bank e r o s i o n a t a r i v e r I n n o r t h e r n C a l i f o r n i a which was f r e q u e n t l y washed o u t by f l o o d s . The $1 m i l 1 i o n f e d e r a l l y funded emergency r e p a i r program m i n i m i z e d e r o s i o n on an e c o n o m i c a l l y I m p o r t a n t f o r e s t lumber r o a d . Eleven-gauge g a l v a n i z e d s t e e l w i r e mesh b a s k e t s were c o n s t r u c t e d and d e s i g n elements I n c l u d e d k e y i n g bottom
g a b i o n baskets I n t o rock o r s u i t a b l e f o u n d a t i o n t o m i n i m i z e s c o u r i n g below t h e bottom b a s k e t . A problem encountered was s i g n i f i c a n t d i f f e r e n t i a l s e t t l i n g o f gabions due t o r e s t r i c t e d d r a i n a g e i n t h e b a c k f i l l . Free d r a i n i n g b a c k f i l l and t h e use o f c o u n t e r f o r t s t o add s t r u c t u r a l s t a b i l i t y were recomnended t o remedy t h i s s i t u a t i o n . Leydecker (1973) d e v i s e d a method u s i n g gabions on low w a t e r c r o s s i n g s f o r secondary roads which proved t o be b o t h economical and a e s t h e t i c . B a s i c a l l y , t h e road a t t h e w a t e r c r o s s i n g i s designed t o g i v e good 1 i n e and grade t h r o u g h t h e s t r e a m . The f i n a l e l e v a t i o n o f t h e low p o i n t o f t h e p a r a b o l i c grade l i n e i s u s u a l l y 6" t o 12" above t h e stream bed e l e v a t i o n a t t h e downstream edge o f t h e r o a d . Gabions 6 ' - 6 " x 3 ' - 3 " are p l a c e d a t t h e f i n a l grade 1Ine w i t h t h e upstream edge o f t h e gabion a l o n g s i d e t h e downstream edge o f t h e r o a d . The gabions are b a c k f i l l e d and stream g r a v e l i s pushed up b e h i n d t h e gabions t o form t h e r u n n i n g s u r f a c e . E s s e n t i a l l y , t h e gabions form a 6" t o 12" h i g h porous dam which r e t a i n s t h e stream g r a v e l .
Stephenson (1980) d e v i s e d c h a r t s f o r p l a c i n g gabion w e i r s on s l o p i n g and h o r i z o n t a l s u r f a c e s . The c h a r t s and e q u a t i o n s were v e r i f i e d e x p e r i m e n t a l l y t o d e t e r m i n e s t r u c t u r a l s t a b i l i t y a g a n i s t s l I d i n g and o v e r t u r n i n g .
G e r o d e t t i (1981) reviewed h y d r a u l i c s t u d i e s which were conducted f o r a proposed r o c k f i l l c o f f e r d a m f o r t h e El Cajon h y d r o e l e c t r i c p r o j e c t I n
Honduras. The c o f f e r d a m had a s t e e l s h e e t p l l e seal i n g w a l l and I t s downstream s u r f a c e was p r o t e c t e d w i t h armoured g a b i o n s .
O s w a l t , e t a l . (1975) conducted a 1:30 h y d r a u l i c model i n v e s t i g a t i o n t o e v a l u a t e bank p r o t e c t i o n r e q u i r e m e n t f o r t h e F o u r m i l e Run l o c a l f l o o d - c o n t r o l p r o j e c t . They found t h a t i n s e v e r a l reaches o f t h e c h a n n e l , t h e f l o w c o n -d i t i o n s r e s u l t e -d i n f a i l u r e o f t h e 3 6 - I n c h r i p r a p , w h i l e t h e m a t t r e s s e s w i t h p r o p e r t o e p r o t e c t i o n reduced t h e scour c o n s i d e r a b l y and p r o v i d e d t h e
necessary p r o t e c t i o n . M a t t r e s s e s r a n g i n g from one f o o t t o t h r e e f e e t t h i c k were i n v e s t i g a t e d i n t h e model. A l t h o u g h no p r e c i s e design r u l e s were e s t a b l i s h e d f o r d e t e r m i n i n g t h i c k n e s s o f m a t t r e s s e s r e q u i r e d f o r s t a b i l i t y a g a i n s t f l o w , t h e r e were s e v e r a l areas i n t h e model i n which 3 6 - i n c h t h i c k r i p r a p and 1 2 - i n c h t h i c k m a t t r e s s e s were s t a b l e . T h i s i n d i c a t e d t h a t t h e r e q u i r e d m a t t r e s s t h i c k n e s s i s no more t h a n o n e - t h i r d t h e r e q u i r e d r i p r a p t h i c k n e s s .
Oswald and Maynord (1978) conducted a s e r i e s o f t e s t s a t t h e U.S. Army E n g i n e e r Waterways Experiment S t a t i o n (WES) t o e v a l u a t e t h e e f f e c t i v e n e s s o f
s e v e r a l schemes u s i n g gabions f o r bank p r o t e c t i o n . S p e c i f i c a l l y , e f f o r t s were d i r e c t e d a t e v a l u a t i n g t h e use o f gabions f o r hard p o i n t s o r t o e p r o t e c t i o n s i m i l a r t o t h e way r i p r a p i s used f o r hard p o i n t s o r t o e p r o t e c t i o n a t s e v e r a l p r o t o t y p e s i t e s i n t h e V i c k s b u r g D i s t r i c t . No r e s u l t s were s p e c i f i e d .
Brown (1979) I n v e s t i g a t e d v a r i o u s t h e o r e t i c a l , e x p e r i m e n t a l and p r o t o t y p e aspects o f t h e use o f g a b i o n - t y p e r e v e t m e n t s . H i s t h e o r e t i c a l a n a l y s i s c o n s i d e r s t h e momentum f l u x o f t h e i m p a c t i n g wave j e t and t h e d e s t a -b i l I z i n g e f f e c t s o f t h i s upon an element o f t h e r e v e t m e n t . L a -b o r a t o r y wave t e s t s were made f o r slopes o f 1:4 t o 1 : 1 - 1 / 2 f o r a v a r i e t y o f waves.
D i f f e r e n t modes o f f a i l u r e were e n c o u n t e r e d , i n c l u d i n g downslope s l i d i n g p r e -d o m i n a n t l y on steep slopes an-d u p l i f t / b u c k l i n g on f l a t t e r s l o p e s . T h i n m a t t r e s s e s showed a pronounced tendency t o b u c k l e . Two e x p e r i m e n t a l panels were c o n s t r u c t e d t o assess m a t e r i a l b e h a v i o r and t o e s t a b i l i t y . Two p r o t o t y p e
r e v e t m e n t s were designed and c o n s t r u c t e d i n accordance w i t h t h e proposed d e s i g n r u l e s .
M o d e l i n g s t u d i e s i n c l u d e work by Posey ( 1 9 5 7 , 1 9 6 9 ) . T e s t s o f e r o s i o n p r o t e c t i o n I n model channels were conducted i n an a p p a r a t u s designed t o p e r m i t comparisons under severe e r o s i o n e x p o s u r e . Comparison w i t h f i e l d i n s t a l
-l a t i o n s shows t h a t s u c c e s s i v e -l a y e r s meeting t h e s p e c i f i c a t i o n s f o r r e v e r s e f i l t e r s w i l 1 g i v e complete p r o t e c t i o n t o t h e f i n e s t , most e r o d i b l e s o i l s
(Posey, 1 9 6 9 ) . A c c o r d i n g t o Posey, a c c u r a t e p r e d i c t i o n o f t h e s i z e s necessary t o p r e v e n t t h e topmost l a y e r from b e i n g washed away cannot be made, and t h i s must be d e t e r m i n e d by t r i a l . I f l a r g e enough stones are n o t a v a i l a b l e ,
s m a l l e r stones w i l l a l s o r e s i s t e r o s i o n bound w i t h mesh t u b i n g .
Posey (1957) a l s o recommended t h e use o f " r o c k sausages" o r gabions when d e s i g n i n g and c o n s t r u c t i n g highway f i l l s . The s i z e o f t h e sausages r e q u i r e d f o r v a r i o u s exposures was n o t d e t e r m i n e d , b u t f u l l - s c a l e t e s t s showed t h a t a
2 . 8
minimum p r a c t i c a b l e s i z e would be ample t o p r o t e c t highway f i l l s under t h e most severe c o n d i t i o n s ( h i g h v e l o c i t y f l o w s ) 1 i k e l y t o be e n c o u n t e r e d .
S i x d i f f e r e n t o u t l e t m o d i f i c a t i o n designs f o r overbank c o n t r o l s t r u c t u r e s were e v a l u a t e d by Copeland ( 1 9 7 8 ) . Model t e s t s were conducted on f i v e o f t h e
d e s i g n s and design v a r i a t i o n s . A 1:24 s c a l e s e c t i o n model was used t o s i m u l a t e d i s c h a r g e s up t o 550,000 c f s . Type 5 o u t l e t m o d i f i c a t i o n d e s i g n , u t i -l i z i n g gabions p -l a c e d p a r a -l -l e i t o t h e f -l o w on a IV on -lOH s -l o p e , was deemed t h e b e s t o f t h e s i x designs t e s t e d .
D u r i n g t h e process o f r e c o n s i d e r i n g t h e r e q u i r e m e n t s o f a r e v e t m e n t / b r e a k w a t e r l a y e r on a c o a s t i n A u s t r a l i a , a s p e c i f i c a t i o n f o r a s t r u c t u r a l l y f l e x i b l e , c o h e s i v e , massive and porous ' b l a n k e t ' was e v o l v e d by Brown ( 1 9 7 8 ) . T h i s s p e c i f i c a t i o n f i n d s an o b v i o u s e x p r e s s i o n i n Reno M a t t r e s s e s , and a s e r i e s o f model t e s t s were c a r r i e d o u t u s i n g stone f i l l e d mesh bags t o r e p r e -s e n t t h e m a t t r e -s -s e -s .
Saunders and Grace (1981) d e s c r i b e d model t e s t s o f channel s t r u c t u r e s c o n s t r u c t e d o f c o n c r e t e and g a b i o n s . T e s t s were conducted a t an u n d i s t o r t e d s c a l e r a t i o o f 1:12 t o determine t h e d i s c h a r g e c h a r a c t e r i s t i c s o f t h e s t r u c -t u r e s , s i z e and e x -t e n -t o f r i p r a p r e q u i r e d -t o p r e v e n -t scour downs-tream o f -t h e s t r u c t u r e s , e f f e c t s o f i c e f l o w i n g over t h e s t r u c t u r e s , and s t a b i l I t y o f t h e g a b i o n s t r u c t u r e s .
S h o r e l i n e s are commonly p r o t e c t e d by stone r e v e t m e n t s , r u b b l e mound g r o i n s o r b r e a k w a t e r s . When t h e e r o s i v e f o r c e s o f waves are l a r g e r , l a r g e s t o n e s o r c o n c r e t e b l o c k s o f s p e c i a l i n t e r l o c k i n g shapes are p l a c e d on t h e s u r f a c e over u n d e r l a y e r s o f stones o f s m a l l e r s i z e . P i l l a i and Verma (1978) t e s t e d i n t h e l a b o r a t o r y p r o t e c t i v e s u r f a c e s o f stones e n c l o s e d I n n e t s
u n d e r l a i n by a g r a v e l f i l t e r . The s i z e o f stones needed w i t h i n t h e e n c l o s i n g n e t was r e l a t i v e l y smal 1 and t h e volume o f stones was reduced c o n s i d e r a b l y as compared t o t h a t i n t h e case o f l o o s e s t o n e s . They concluded t h a t t h e d e v e l -opment o f s t r o n g and d u r a b l e s y n t h e t i c f i b e r s p r o v i d e s f o r e f f e c t i v e use o f stones enclosed i n n e t s t o p r o t e c t t h e h i g h e r p a r t o f beaches.
Nasser and McCorquodale (1974) s t u d i e d unsteady nonDarcy f l o w i n r e c -t a n g u l a r r o c k - f i l l embankmen-ts w i -t h i m p e r v i o u s cores by s u b j e c -t i n g -t h e embank-ments t o n o n l i n e a r , s h a l l o w w a t e r waves. Crushed rock and q u a r t z were
u t i l i z e d , i n s i z e s r a n g i n g from 0.7 cm t o 4 . 4 cm, t o b u i l d e x p e r i m e n t a l
embankments o f v a r i o u s w i d t h s . The waves i n a l l e x p e r i m e n t s were n o n b r e a k i n g . The embankments were t e s t e d f o r s e v e r a l wave c o n d i t i o n s . E m p i r i c a l f o r m u l a s
are p r e s e n t e d f o r t r a n s m i s s i o n , r e f l e c t i o n , r u n u p , and rushdown, and a l l g i v e good c o r r e l a t i o n s . An upward s h i f t o f t h e mean w a t e r l e v e l i n t h e embankments was d e t e c t e d d u r i n g t h e e x p e r i m e n t s . I t was found t h a t t r a n s m i s s i o n decreased w i t h d e c r e a s i n g c o n d u c t i v i t y and i n c r e a s i n g wave steepness and embankment w i d t h , and t h a t r e f l e c t i o n decreased w i t h i n c r e a s i n g c o n d u c t i v i t y and w i d t h o f embankment.
E x p e r i m e n t a l work on m o n i t o r i n g s t r u c t u r a l d e f o r m a t i o n o f gabion w a l l s has been done by Veress and Hatzopoulos ( 1 9 7 9 ) . D u r i n g t h e course o f t h e p r o j e c t ( V e r e s s , e t a l . , 1 9 7 7 ) , p r a c t i c a l t e s t s o f t h e t h e o r e t i c a l d e v e l o p -ments were done on an i n - p l a c e gabion w a l l . The m o n i t o r i n g c o n s i s t e d o f
pho-t o g r a p h i n g pho-t h e s pho-t r u c pho-t u r e from pho-t h r e e camera s pho-t a pho-t i o n s . The camera was m o d i f i e d t o a p l a t e camera t o p r o v i d e t h e maximum a c c u r a c y . The methodology c o n s i s t e d o f t h e g e o d e t i c d e t e r m i n a t i o n o f t h e camera l o c a t i o n and t h e o r i e n t a t i o n and p h o t o g r a m m e t r i c d e t e r m i n a t i o n o f t a r g e t s ( n a t u r a l and a r t i f i c i a l ) on t h e s t r u c t u r e . D u r i n g t h e course o f t h i s p r o j e c t more than 100 t a r g e t l o c a t i o n s were d e t e r m i n e d by t h r e e dimensional c o o r d i n a t e s . The maximum e r r o r was found t o be p l u s 3/4 i n c h ; t h e a v e r a g e , 1/2 i n c h . T h i s r e p r e s e n t s a r e l a t i v e
accuracy o f 1/58,000 t o 1/120,000 o f t h e p h o t o g r a p h i c d i s t a n c e . Using t h e a c t u a l c o n s t r u c t i o n s i t e f o r r e s e a r c h p e r m i t t e d Immediate i m p l e m e n t a t i o n . The i n s t r u m e n t a t i o n as w e l l as t h e methodology a l o n g w i t h t h e computer program was t r a n s m i t t e d t o t h e Washington S t a t e Highway Department and t h e i r
Photogrammetric Branch was a s s i s t e d i n t h e I m p l e m e n t a t i o n .
A f t e r r e v i e w o f t h e a v a i l a b l e 1 i t e r a t u r e , i t was found t h a t v e r y l i t t l e i n f o r m a t i o n r e g a r d i n g t h e design o f m a t t r e s s e s f o r p r o t e c t i n g r i v e r channels and c a n a l s e x i s t e d . Most o f t h e model s t u d i e s f o r d e s i g n i n g m a t t r e s s e s was f o r p r o t e c t i n g t h e c o a s t a l o r shoal 1 i n e a g a i n s t wave a t t a c k i n g and was q u i t e s i t e s p e c i f i c . A g o s t i n i and P a p e t t i (1978) recommended a t h i c k n e s s o f Reno M a t t r e s s r e l a t e d t o f l o w v e l o c i t i e s (see Table 2 . 1 ) and p r e s e n t e d h y d r a u l i c t a b l e s f o r v a r i o u s roughness c o e f f i c e n t s and channel g e o m e t r i e s . They found by comparing t h e use o f m a t t r e s s e s w i t h t h e use o f r i p r a p t h a t a s a v i n g o f 25 t o 30 p e r c e n t c o u l d be o b t a i n e d by u s i n g t h e m a t t r e s s e s . A d d i t i o n a l l y , a s a v i n g s o f a t l e a s t 50 p e r c e n t i n reduced wastage c o u l d be o b t a i n e d by u s i n g m a t t r e s s e s f o r underwater i n s t a l l a t i o n as compared t o u s i n g the r i p r a p under w a t e r .
2.10
Table 2 . 1 . Thickness o f Reno M a t t r e s s R e l a t e d t o Water V e l o c i t y .
Water V e l o c i t y M a t t r e s s Thickness m/sec m 0 . 9 - 1.8 0.15 1.8 - 3.6 0.15 - 0.25 3.6 - 4 . 5 0.25 - 0.30 4 . 5 - 5.4 0.30 - 0.50 and g r e a t e r
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