Appropriate techniques for triaxial testing of saturated soft rock

136A

flexibility matrix principle is again used. The method is very useful in the analysis of problems involving incompressible materials.

Properties of Rocks and Soils 835011 APPROFRIATE TECHNIQUES FOR TRIAXIAL TESTING OF SATURATED SOFT ROCK Chiu, H K; Johnston, I W; Donald, I B Int J Rock Mech ~in Sci, V20, HS, June 1983, Pl07-120 Presents results of a detailed investigation to evaluate the influence of a number of f a c t , s on the results of triaxial tests on a Sil~rian mudstone from Melbourne, Australia. Consideration is given to the appropriate trlaxial eqttlpment and associated measuring systems for the determination of stresses, strains and parewater presst~res. The preparation of test specimens and their geometry is examined and rates of strain application are investigated. By considering the influence of these factors in comJumction with the basic soft rock characteristics, it is demonstrated that er~ineering prolxm-ties independent of procedures may be derived from the triaxial test. ~2 refs. 835012 GEOTECHNICAL PROI~TIES OF AN A T T A I ~ I T E ~?JU~E IN NGRTHWEST~N NIGERIA Ola, S A Engng Geol, VI9, NI, Dec 1982, PI-13

CLAY

M!neralog~cal aralysis of the clay shale from the lullemmeden Basin s Nigeria showed it to be predominantly attapttlgite. The liquid limit was found to be very high: about 200 per cent. A very low maximum dry density of l l B V k ~ c u m, a high optimum moisture content of ~i per cent, and a high compression index of 0.23 were f o ~ . Shear strength test results indicated a loss of strength of 50 per cent as a result of decrease in strain rate. Effective cohesion was fotmd to be zero in all tests. 835013 APPLICATIONS OF ADVANCED lABORATORY TESTING TO GEOTECKNICAL I=RACTICE Sills, O C Ground Engng, V16, N3, April 1983, P7 Report of an informal discussion of the British Geotechnical Society on 27 October 1982, on soll testing techniques. This incl~ded discussion of stress path testing and development of measuremerit techniques for particular soil tests. 835014 MULTI-PURPOSE ROCK CORE TESTING DEVICE Swan, G; Olofsson, T Geotech Test J, V6, NI, March 1983, P18-23 A multipurpose rock tester that incorporates a microcomputer for data logging has been developed. The instrument is capable of determining: Youmg's modulUs, Poisson's ratio, indirect tensile strength, point load index, fracture toughness, and Joint normal stiffness. The tester has enabled testing of larger rock specimens at reduced costs. 835015 SAND STRESSES AROUND AWW~T~ORE Risnes, R; Bratli, R K; Hersrud, P Soc Pet Engr J, V22, N6, Dec 1982 , I~83-898

Stresses in the sand around ~ wellbc~e ~re considered. Theories of elasticity ~ plasticity are applied together with the ~ssum.ptlon that the rock obeys the Coulanb criterion. It is concluded that in a poorly consolidated sand there is a plastically strained zone Just around the ~ellbore. k~en an incom~pressible fluid is a!ic~ed to flow into the uncaged re21, the plastic zone is found to grow ~-ith f l ~ ratej and a stability criterion describing the failure of the sand is found to exist. OF ST!FE.NESS AND OTHER JOTh~P PRO835016 D E q ~ N A T I O N PERTIES FROM ROUGHNESS ~ A S U R ~ N T S Swan, G Rock Mech Rock Engng, V16, h~, Feb 1983, P19-38 The measurement of surface profiles is presented as a useful and simple approach to classifying statistically the essential features of rock Joints. Existing analytical Joint contact models for normal loading are examined and a discrete numerical technique developed. This technique is used to examine the behaviot~ of different slate Joints. The relationships between normal stress, stiffness, true contact area and initial aperture are shown to be simple for these Joints. Experimental evidence is used to substantiate the m2nerical results. 835o17 SURVEY OF THE PHYSICAL PROPERTIES OF SOME CARBONATE ROCKS Bell, F O Bull Int Assoc Engng Geol, N~4, Dec 1981, P!05-110 Samples were taken from the Carboniferous Limestone, the Magnesian Limestone, t h e Inferior Oolitic Limestone and the Great Oolitic Limestone. Their specific gravities, dry and saturated densities were determined, as were their absolute and effective porosities. The densities decreased and porosities increased with decreasing age of the limestone concerned. The permeability of these samples increased as the porosity increased. Fm-thermc~e the strength decreased with increasing porosity. When saturated the strongest limestone showed the least percentage reduction in strength. The strongest limestone also possessed the highest values of hardness, the weakest having the lowest values. The Young's modulus tended to increase as density, strength and hardness increased. The Carboniferous Limestone recorded the highest values of Yourg's modulus, the Great Oolitic Limestone the lowest. Poisson' s ratio and related elastic properties were also determined. 835o18 GEOTECHNICAL PROPERTIES OF SOME EVAPORITTC ROCKS Bell, F G Bull Int Assoc Engng Geol, N24, Dec 1981, P137-14h The physical properties of four evaporitic rocks, anhydrite, gypst~n, potash and rock salt, were investigated. Their respective specific gravities anl dry densities show little variation and all four rock types have low porosity values. Anhydrite is by far the strongest material both in unconfired compression and in tension, followed by gypsum, potash and rock salt, in that arder. The hardness values of these four rock types follow the same order as the strength values, to which they have a highly significant relationship. All four rock types exhibit some amount of plastic deformation