~A

81~o66

Experimental results :~re reported for true triaxlal t e s t s on a porous limestone to determine the yield surface in stress Sl>~ce, +/%..- flow rule, a~i i~iuced amisotropy. The ir4tial yield sm-face is obtained by compression te~ts, extension tests ~md a hydrostatic ~+n~ess test. Permanent deforma- tion occur~ under a hydrostatic stres~ for t~he dry, IX~OUS !~mestone used in the~e teats, thus the initial yield surface forms :~ closed surface in stress space. Ncrmslity of the str~in in- crement vector with respect to the yield surface is investigated by using d~fferent loadlm~ psth~ in stress space. Frc~ these different paths of lo~iing the morms~Ity l~rinciple can ~e v~rified. Work hardening along one axis ~roduces changes of the yield stress along the other axes so a sample that was initially isotropic becomes a~isotropic as a resttlt of the work hardening.

LIQUEFACTION OF DIFWFRENT MINE TAILINGS UNDER STRESS CONTROLLED LOADIIW} Highter, W H; V~1_lee, R P Engmg Geol, V!6, NI-2, 1980, PLY7-150

Describes consolidated-undrained stress controlled triaxial tests on garnet ani zinc tailir4~s. The results are m~rised by i~e critical void ratio or steady s-~ate ctu-ves. Despite similsr index l~operties the ~teady state curves for g~rnet and zimc differ.

815067 VT~SATILE HOLLOW CY~IND~.~ ."~IAYIAL DEVICE Dusseault, M B Can Geotech J, VI8, I~-, Feb 1981, PI-7

81~o68

815o69

Describes a high-~ass~re, thick-walled hollow cylimder tri~xial device designed to ~rovide data from tests with caref111 stress path control - radial strain tests, axial atrain-contrc~led and stress-co~trolled tests ani ccc~resslbility ~ests. Presents results of cyclic plane axial s~r~in c~essibility tests on dense Ottawa sands.

STRESS-STFJ~IN RELATIONSHIP FOR GRA~V~LR MA_e~IALS DERIVF~ FROM M~CROSCOPIC SHF;~ M~CEAI~

Matsuoka, H; Takeda, K Soils Foumd, V20, N3, Sept 1980, P~-~8

Simple shear tests were carried out usimg a pile of alu~inium rods to simulate ~rcmmlar materials in a two ~mensionsl state. Granular materials are cor~idered to be a unit elmment composed of two particles, termed 'two particle models'. Slidi~g displacements between two particles a c r o s s t h e ~ t e z t i a l s l i d i n g p l a n e were f~cmu- lated by considering the mechanism of ~isalm~ear- ar~e a~i generation ~f angles of i~ter~Icle contacts. A stress-st~aln relationship was derived from the a!idlmg displacements ami compared with the results of cyclic simple shear tests on alumlni~m rod mass. Strems-straln characteristics of a sa~i u~i~ cyclic loadimg were explained ~y the proposed e~uation.

BEKAVIOR OF G ~ MATERIALS IN SIMPLE SHE~/R Nemat-Nasaer, S Soils Found, V20, HS, Sept 1960, P59-73

Presents a simple model for two dime~.slomal deformation a~i flow of granular material accounting for initial denslflcation~ subsequent dila~rncy ax~ t h e n e t smount of der~ificatlon which accompanies cyclic shesrir~.

815070 STrESS-STRAIN BF}La.VIOUR OF AN IDEA!IZED P~qSO- TROPIC GPA~SAR MATFLRIAL

Tat suoka, F Soils Found, V20, N3, Sevt 19~0, P75-90

Presents a simple elasto-plastic theory for anisotro~c gre-.mllsr materials incorporat~ ng aniso+~opic yielding, plastic Ix~,ential furntious and en~iricBl, hardening which involve perimeters ex~m'e~s~ng inherent anis~cropy. Inhere~ anisO+~rOpy ar~ arlsotropic yielding in three dimensior~l stress conditions can be modelled by this theory.

81~)71 WHAT CONSTI~JTES A ~RN~ TECH}~CAL NGPE ~.ov~cs, ~.~ D Ceotee_h Test Y, V3, N3, Sept 1980, P127-130

Proposes a definition of a turn of rope arovmd the cathead used to perfca~, the. sta~iard penetration test. The d~f~erence betweez clock- wise sni counterclockwise rotation results in substantial wariation in the ez;ergy delivered to the s~mple and in the blow ccu~t for the same soll coz~itiom~.

815672 DEVF~RWENT OF HOLOGR~PHIC TECHEqQ~ES TO ~glX~DY THeY INDUCED DF~CAT!ON

Gilbert J A; Vedder, D T Exp Mech, V21, N~, A~ril 1980, P].~8-1~4

The effect of urifcrm tamperature rise on limestone specimen is ~nalysel. Displacement ~:tterns are o~talmed using ~ holographic- Moire technique. These patterns ~re smalyse~ for strain due to teml:~'a~Te ir~rease. Trans- formation equations are applied to ~redict l~rlr~ipal streir~ and their correspondi~ directions. V~lues obtained for thermal coefficients of exI~nsion aEree with the more co~ventionsl ~(~erlmental .methods.

8~o~3 MEASUP~ OF ~.~ ELASTIC TENSOR IN ROCK-LIEE ANT OOTROPIC MATERIALS

Cotza, R; Mar~a, P P; Vivanet, C Proc 21st US Symposimm on Rock Mechanics,

Rolls, Mi.-souri, 28-30 ~ay 1980, 92~9"~5~

Demonstrates mathematically that for linearly elastic ~terial~ it is po~slble to determine experimer~tslly all the 21 independent components of the elastic tensor by carrying out :~ni.qxlsl comlm'ession tests on prismatic sample~ c~t from 6 directions in the material. It is not neces38ry to make amJ assumptions about the anisotro~t ~ the msteri~!, Results of tests on a mlcrocryst~llin~ limestone are ~esented.

815o74 PERFORATED PHOT~.ASTIC CO~LNGS .TO X~2ASURE LOW GRADIim/~f STRAIN IN ROCKS

Sknxtrzyk, F J; Aughenbau~h, N B Proc 21st US Symposi~ on Rock Mechanics,

Rolla, Missouri, 28-30 May 1980, ~06-516

Proposes a method that employs a _.~erfcr~ted i~otuelastic coating to measure principal stral~s a~d their directions. The photoelsstlc c~,ting is perforated with city,Afar holes. Around each hole the coating is protect~i against cementir~ to the rock surface. The theoretical background fc~ the method, i~ presented ~md the response of the perforated l~hotoelastic coating to s~ b~axial strain field is discussed. As an ex~,~le cf how thls technique can he ~pplied, this paper briefly describes its use to measure the time- dependent recovery of well cores to establish ~n situ stress conditions.