Undrained behaviour of Johor sand in cyclic triaxial test

Abstract

As liquefaction due to earthquake hazards may occur on both clean sand and soil comprising of sand with fines, the current research trend is more focusing on determining the boundary limits of liquefaction susceptibility of sand matrix soils. Series of laboratory testing had been carried out worldwide but many of the results are contradictory. It is thus important to first determine the condition in which the clean sand is most susceptible to liquefaction, only then the liquefaction susceptibility of sand matrix soils could be compared and discussed under this specific condition. Stress controlled triaxial test apparatus was used to shear the isotropically consolidated sand samples under undrained two-way cyclic loading until the initiation of liquefaction. The liquefaction was defined based on: (i) excess pore pressure was equal to effective confining pressure or (ii) a double amplitude strain of 5 % was reached, whichever was achieved first The results of two-way cyclic triaxial tests on clean sand showed that besides the cyclic stress ratio, the liquefaction resistance of the sand under undrained loading was proportional to effective consolidation pressure and density index. The clean sand was more liquefiable at loose state (ID = 20 %) and under low effective consolidation pressure (100 kPa), when subjected to earthquake loading.