EFFECT OF FRICTION-LESS ENDS ON TRIAXIAL SHEAR TESTS

Abstract

Experimental tests have been made to check the suitability of the enlarged and lubricated end plates as frictionless ends. A modified pore-pressure sensing device has been suggested which has proved equally useful as porous device for drainage during the consolidation period of the triaxial test. The enlarged and lubricated end platens were found to be remarkably successful in allowing the lateral expansion of the ends of a triaxial specimen during the shearing pe.:iod. With the use of frictionless ends in triaxial tests, relatively uniform stress distribution and deformation was obtained.. The more uniform development of dilation,resLlted in a tendency towards formation of multiple failure surfaces. It was confirmed from the tests that effective stress parametersØ' as obtained by triaxial test ' with ordinary ends arc slightly on unsafe side. In undrained tests, frictionless end platens reduced the large, variations in the water content of various sections of the triaxial sample after shearing. Tests indicated that the short length samples (H/D = 1) combined with frictionless caps will give better results than long samples with ordinary ends.