Voorstel
Studie "Acoustic Emission" gedrag v a n
verschillende grondsoorten S-80.038 1981
door
H.
v . d . Kogel LGM A. Penningcow
- 1 -
Proposal Acoustic Emission Studies
on
S o i l s , 1981During spring 1980 the question was raised whether the method of Acoustic Emission ( A E ) could contribute t o the assessment of the
s t a b i l i t y o f Dutch dikes. This resulted i n a short memorandum which contained a description of the method and a short l i t e r a - t u r e survey. In the course of preparing the memorandum Prof.
R.M. Koerner of the Drexel University, Pennsylvania, USA was con- tacted *
In the COW-LGM committee meeting of March 2 7 , 1980 i t was decided t o i n v i t e Prof. Koerner for a three day visit as a j o i n t project of COW and LGM. The purpose of t h i s v i s i t was threefold: t o intro- duce the method i n the Dutch soil mechanics community, t o familia- r i z e Prof. Koerner with LGM, COW and some problem areas and f i n a l l y t o sketch a proposal f o r further study. The f i r s t p a r t was effectuated by discussions on the s t a t e of the a r t between Prof. Koerner, A . Penning ( C O N ) and
H.
van der Kogel ( L G M ) . Furthermore two lectures werescheduled: one on September 1, 1980 a t LGM f o r an invited audience and the other on September 3 a t the Delft University of Technology on invitation of the Dutch Royal Society of Engineers (KIVI). The second part was substantiated by a tour of LGM a n d a f i e l d t r i p on September 2 , 1980 where we visited three problem areas namely "Polder Middel b u r g "
,
"Boonervl i e t " and "Gorinchem", The l a s t p a r t consisted of a temporary s e t u p of further work which resultedi n the following proposal.
During the discussions and presentations i t became evident t h a t the method of AE
s t a b i l i t y of earth dams in the USA. In f a c t several agencies adapted the method (see Appendix I ) . Furthermore d u r i n g the l a s t ten years a considerable e f f o r t has been pursued on the academic level t o such an extent t h a t i t can be stated t h a t A E a r e indeed generated by deforming s o i l s (see Appendix 11). The work of the Drexel group on A E
pub1 i c a t i ons.
A l t h o u g h a wide variety of experiences with AE
been obtained, the question remains whether t h i s experience i s applicable t o the Dutch s i t u a t i o n . I n other words i t i s necessary t o establish the AE signature of Dutch soils. In the s p i r i t of the above we propose the following studies.
has been succesfully used t o monitor the
in s o i l s has been documented with some 37
- 2 -
A. Laboratory studies a t the Delft Soil Mechanics Laboratory _I_.
W propose t o t e s t the emittivity e of three "typical" types of s o i l : sand, clay and peat. W will perform a so called frequency e analysis in which we establish the frequency content of the emissions and t h e i r strength. For this purpose we will use
LGM
existing t r i a x i a l apparatus, i n s t a l l an accelerometer in the bottom p l a t e and buy recording equipment. Tabel A gives more extensive informati on.
B. Laboratorv studies a t the Drexel Universitv
Due t o non-existing data on " f a t t y " clays and peat we propose a concurrent s e r i e s of t e s t s
on
clay and peat a t Drexel. Moreover t h i s action generates a reference point for the a t the moment unexperienced personnel ofLGM
w i t h respect t o A E . An outline of the t e s t s e r i e s i s given in table B,C. Demonstration experiment
After establishing the signature of the d i f f e r e n t s o i l s we propose t o perform a demonstration in order t o show the f e a s i b i l i t y of the method in a r e a l i s t i c boundary value problem. The classical plate bearing t e s t seems s u i t a b l e from the point of view of a v a i l a b i l i t y and cost. We propose t o measure the AE i n a sandy subsoil while measuring concurrently the displacements and the force on the plate until " f a i l u r e " . This generates a displacement / AE count curve, which should demonstrate the r e l a t i o n between trends
i n AE count and trends towards f a i l u r e .
D. Field monitoring
Finally we propose a f i e l d monitoring experiment in the problem area "Boonervliet". We will i n s t a l l a wave guide outside the deforming area as wel1 as inside the deforming area. The f i r s t one gives U S an indication about the background noise, while the second one generates the "signature" of the deforming area. Moni- toring the AE over a longer period o f time will reveal something
a b o u t the trends in AE i n d i f f e r e n t seasons, which m i g h t be correlated w i t h surface d i splacement measurements i f necessary.
We will t r y t o use a s much a s possible the existing experience in order t o avoid unnecessary duplication. We hope t h a t a f t e r the proposed work we will be i n the position t o e i t h e r s u p p o r t more practica1 problems in t h e Dutch environment ( a n d ) or s t a r t
Tabel A inventarisation i nstrumentati on and acqui s i t i o n one t e s t set u n i t design and insta1 lation o f AE sensor in t r i a x i a l apparatu s (
LGM)
sampling and transporta t i on experiments on sand, clay, peat. ( t o t a l 3%15 samples) frequency analysis>
>
reporting
+
di scussions
Time Sc hedu 1 e a nd cos t
1 2 4 6
-
cast f 40.000,- f 5.000,- f 15.00C),-f
40.000,- p.m. f 14.000,- time (months)-
Tabel i3 (Koernerì experiments on clay, peat. ‘4 ( t o t a l 30 samples) including r e n t o f / t e s t unit frequency analys reporting t discussions travel t accomodati ons Total s >
Time sc hedu 1 e and cast
1 2 3 cost $ 6150 $ 1650 $ 2000 $ 2500 $ 12.300,- time (months) .---+
I
I '
Demonstration experiment I
Cost: (reporting t. experiment): f 4.200,-
+
f 3.000,-Time experiment: "Time " re p o r t i ng : Cost: (LGM): Time experiment: "Time" reporting: two days 1 4 days Field experiment f 10.000,- one year one m o n t h
, Appendix
I
U.S. Agencies Using an, lor Evaluating the AE Method
0 U.S. Environmental Protection Agency (smal1 earth dams)
Contact: Dr. John E. Brugger
Industrial/Environmental Research Laboratory
U.S. Environmental Protection Agency Edison, New Jersey 08817
U.S. Bureau of Mines (tailingsslopes and mine safety)
Contact: Mr. Frederick W. Leighton Supervisory Mining Engineer
U.S. Bureau of Mines Denver Federal Center Denver, Colorado 80225
U.S. Department of Transportation (tunnel stability and excavation stability)
Contact: Mr. John R. Salberg
U.S. Department of Transportation Federal Highway Adminictration Washington, D.C. 20590
*
U.S. Department of Agriculture (earth dam stability, settlement and subsidenc)Contact: Mr. Gerald N . Gibson Soil Conservation Service
U.S. Department of Agriculture
P.O. Box 5 3 1
McCo ok
,
Neb ras ka 69001Summary of A.E. S t a b i l i t y Monitoring
of Clope S t a b i l i t y Problems
Robert M. Koerner, Ph.D., PE
Appendix I1
The a c o u s t i c emission monitoring technique has been used f o r t h e purposes of s l o p e s t a b i l i t y assessment i n a number of s i t u a t i o n s . Table 1 following l i s t s some of t h e s e cases. While i t i s d i f f i c u l t g e n e r a l i z e f o r a l 1 circumstances, t h e s e p a s t s i t u a t i o n s have l e d t o t h e following emission c l a s s i f i c a t i o n s t a g e s .
e S o i l masses t h a t do n o t generate a c o u s t i c emissions are n o t deforming and are s a f e . Such s t r u c t u r e s are i n a s t a t e of
e q u i l i b r i u m and need not be i n s p e c t e d f o r a considerable t i m e o r u n t i l a new loading c o n d i t i o n i s encountered.
e S o i l masses t h a t generate a c o u s t i c emissions t o a moderate degree (from 10 t o 100 counts/min. f o r t h e equipment and s e n s i t i v i t i e s c u r r e n t l y used) are deforming s l i g h t l y and are t o be considered marginal. Continued monitoring of such cases i s r e q u i r e d u n t i l such t i m e t h a t t h e emissions cease o r t h a t they i n c r e a s e t o t h e following condition.
O S o i l masses t h a t g e n e r a t e l a r g e amounts of a c o u s t i c
emissions, (from 100 t o 1000 counts/min. f o r t h e equipment and s e n s i t i v i t i e s c u r r e n t l y used) are deforming s u b s t a n t i a l l y
and are t o be considered unstable. Immediate remedial measures
are r e q u i r e d which, i n t h e case of e a r t h dams, could be t o
decrease t h e loading o r t o add downstream b e r m u n t i l e q u i l i b r i u m
i s re-established. It i s important t o n o t e t h a t i f a c o u s t i c emission monitoring is continuing during t h e s e remedial measures, t h e technique w i l 1 b e f u n c t i o n i n g as a c o n s t r u c t i o n design a i d
which g i v e s an i n s t a n t assessment of t h e remedial measures
as t h e y are i n p r o g r e s s .
S o i l masses t h a t g e n e r a t e v e r y h i g h a c o u s t i c emission l e v e l s
( g r e a t e r t h a n 1000 counts/min f o r t h e equipment and s e n s i t i v i t i e s c u r r e n t l y used) are undergoing l a r g e deformations and can be c o n s i d e r e d t o b e i n a a f a i l u r e state.
stream r e s i d e n t s and t h e i r p e r s o n a l pmsperty s h o u l d b e
immediately i n i t i a t e d .
e
.
4 1 ?a416 2 Pa-617 . 3 Xeb-200 i Ra-asc M 9.g 2600 66 20.x 2500 40 ì 2 . t 300 67 20.4 900 800 760 270 90 37 180 210 . 10 krr 180 t k p > 150 140 6 ' i a 370 fwcc2lcnt &Ce&?Bt ExceElsnr cood ; c'od , Exce11ear Good Poot Execltmt Poor Poor Poor Poor Poor Cood Excellent 20 rodo Excalient 12 tod8 Colcpres3lble I2 re-bJr8 POQr 2 PtPeS 1 PiFe . 1 re-bar Poor . 1 píle 3 rods CoiqrtssLbsbra 6 rods O O 0-200 c-20 2-750-
-
2-10 0-5 . W O 0-3 2-100 10-190 . 2-ffO0 20480-
0-4 0-60-
-
-
s Ps-PI+ 6 Neb3908 7 Can-LW 8 Del-Goc 9 Pa-WB 10 HJ-HLX ll v a - m 12 Hy-osu 13 Pa-DSPI 14 Pa-DSPZ 1S Pa-L! 16 f c x 4 17 Xy-WC 18 bel-ol 19 -SS 20 I 5 8 4 21 VA-R za UY-ASP 23 üä-fls? 24 lm-xs . . 2s rksccr Suscharge laad 6 ì . 8 120 F l w d eontrol Taíllngs d r s 68 20.8 600 95 29.0 900 Cood Cood Excellent verg poor Un'mcvn UnlCnoM G o d Cood Poos Tomr &%rage caod-
-
" 3 rods 3 p i p e s ii r0a5 12 ra-bare 12 r o b . 4 rods 6 rods I red 4 rada 8 rodo-
S rod. 1 cnstng 3 rods ' --
-
Contafnfng dreàg- i n g spo11 Water Supply Contain cheaícal Conrain c h e ~ i c a i vaste tontaán petro- leua vaste Stockpiie fot higiway f i l l Stockpila for highvog.fi11 SeeFagt baicath e a i t h dan Cypsurn dam Sludge and mate-water iagoons Water reseraoir vaste 1s: 4.6- 5 ii 40 12.2 120 SS.6 600 8 2.4 4 af 4- 1.2- 500 i5 4.6 U 4.6 29 15 4.6 60 I I
