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831032 Mb'LTI~AL LOADI'~ OF LARGE DI~, THYN-W~T.T~ TOmE ROCK SPECIMENS Hecker, S S; Petrovlc, J J Geophys Res Lett, VS, NT, July 1981, F~03-706

A large scale mechanical testing facility permits previously impossible thln-walled t u b e m u l t i . a x i a l loading exp~iments on rock materials. Constraints are removed regarding tube wall t h i c k n e s s i n rel- ation to rock microstructural features a~ t ube d i ~ as well as test machine load ca;acity. Thi~-walled tube st~Lies clarify t h e i~fl~leDce

intermediate l~inaipal stress on rock fracture amd help define a real~stic rock fracture criter- ion far all multiaxial stressimg situations. By comparing results of t~ain-walled ar~ thick-walled tube fracture investigations, effects of stress gradients can be established. Firefly, infl~emces of stress path on rock fracture, an area largely ignored in current rock failure criteria, can be examined in detail using controlled loading changes as well as specimen prestrains. Auth.

831033 LARGE SCALE LABCRATGRY TESTING OF HYDRAULIC FRACTURING Haimson, B C Geophys Res Lett, VS, N7, July 1981, PTIS-71B

Discusses the importance of rock fracturimg, limitations c~ mr~ll sca le laboratory testing, laboratory research needs in rock fract~ri~, advantages of a large scale testIDg facility (Ira cubes cr im diameter cylird~s), sylimdrlcal vs cubical specimens.

831034 IN-SITU STRESSES: THE FR~X~NANT Ih~//ENCE ON HYDRAULIC FRAC%~KE CONTAIR~NT

Warplnsk~, N R; Schmldt~ R A; NcTthrop, D A J Pet Technol, V~, N3, March 1982, I~5~3-66~

In situ hydraulic fracture experiments havo b e e n conducted to determine t h e parameters %hat control hydraulic fracture containment. S~'ess differ- ences between t h e ~ zone and a boumding layer were found to be t h e most ~ c o n t r o l l i D g factor. Interfaces between materials of different properties was shown to have l i t t l e effect.

831o35

831036

Strength characteristics See also: 831051, 831074, 831081

EXPERIMENTAL STUDIES ON THE INFLUENCE OF ROCK ANISOTROFY ON SIZE AND S~%FE EFFECTS IN H)I~T- LOAD TESTING. TECHNICAL NOTE Gr eminger, M Int J Rock Mech Min Sci, V19, N5, Oct 1982,

P241-246

Point-load tests were carried out on 4 rock ty~es of various degrees of stremgth anlsot~: A~e~ gneiss, Ruhr-sandstone, ChiaDdone-Gneiss a t 4 Nuttlar-Slate. Size add shape effects weTe foumd to be indel~ndent of the degree of rock anls~ and of the loadimg direction. The use of a refer- ence point-load index to predict umiaxial cumprse- sive stremgth was also studied amd it was con- eluded that use of the index could lead I;o ~i~- ficant errors.

EXR~IMENTS IN GEOTECHNICAL FABRIC-REIRFCRC~) S01L B~IAVIOR Ha//burton, T A; Lawmaster, J D Geotech Test J, V4, N4, Dec 1981, P153-160

Describes a study to investigate the me~cs of geotechnleal fabric lateral restraint rein- forcement of a cdhes io~ .ess soll mass placed above the fabric. A l~obable theury of the reinforcement mechanism is Iro~osed. LO,B~ b e a r i z ~ tests, carried out with 4 different geotextiles, in c~der to ;wove or disprove the theury are described.

831037 ELECTROPNEY~ATIC CYCLIC LOADING SY~ Chart, C K Oeotech Test J, V4, ~, Dec 1981, P183-187

Reviews same uf the systems available for the application af cyclic loads to aoil specimens: pmemmtic actuator loadimg systems, electrohyd- raulic closed-loo~ systems add electromagnetic systems. Their main features add l~imciples of operation ere described. A n~w electropneumatic system is then described.

831038 LINEARIZING TRIAXIAL TEST FAILURE ENVELOPES. TECHNICAL NOTE

Handy, R L Geot~h Test J, V4, N4, Dec 1981, ~88-191

A correct regression amalysis can be quickly per- formed on p-q triaxial test data plots (where p re;~esents the abscissa of the centre of a M~r circle and q is t h e radius). This is dome by con- vertimg the p-q data paints to polar cocrdlmatesj adding 45 deg ur another angle indicated by the mean stress paths, converting back to recta~ar coord/mates, and then perfcrmlng the linear reg- ression. This leads to a mere accurate estimation of the friction amgle.

831039 CONSTANT-VOLUME TRIAXIAL TESTS TO SI~DY THE ~'F~.CTS OF MEMBRANE PENETRATION

Ramam, K V; RaJu, V S Geotech Test J, V4, N3, Sept 1981, PI17-122

Repmrts on the effect of membrame penetration on pore l~esst~e response in isotroplcally consolida- ted static and cyclic urrlrained triaxlal tests. The effect was studied by performing on saturated sand samples both conventional and constant- volume tests in which volume chamges caused by membrane penet~'atiom were elimimated by a ccmpen- sat/on technique. Resulting pare pressure response and stress path behaviour are discussed.

8BI0~0 STATIC FLATE LOADING TESTS ON OVERCONSOLIDATED CLAY Andersen, K H; Ster~ha~r, p J Geotech Er~ng Div ASCE, VI08, NGT7, July

1982, m9i8-93~

Three in situ static plate loading tests carried out on a medium stiff, overeonsolidated clay dep- omit are described and interpreted. In addition to the plate loading test results, the results frc~ undrained static laboratory tests on Haga clay are also presented. The project aimed mainly at investigating t h e reliability of using labor- atory tests to determine the in situ static shear strength and stiffness of overconsmlidated clays. It was possible to obtain reasomably good agree- ment between measured anl calculated values of bearimg capacity and displacements, provided the calculations were based on laboratory tests with the same type of load application amd the same f~ime to failure as in sltu. For the displacement calculations it was essential to account for load ~strlbutions amd the very nonllmear s t ress - straln properties. Auth.