Abstract
A simple and useful technique whereby the membrane penetration which causes errors in the effective confining stress during an undrained triaxial test on a coarse-grained soil can be substantially reduced has been developed. In this method, a thin membrane penetration reducing layer (MP-reducing layer) is made on the surface area of a triaxial specimen with Toyoura standard sand, whose accurate membrane penetration characteristics have been determined by many researchers and have been established in laboratory undrained tests. The results of a series of cyclic undrained tests indicated that the proposed method can provide test data only with a known membrane penetration amount of Toyoura standard sand, when forming an MP-reducing layer with a thickness approximately the mean grain size of test material. This method has advantages over existing methods because it only requires placement of Toyoura standard sand around the test specimen and does not require special devices nor is it based on questionable assumptions.
