Experimental study on shear strength parameters of municipal solid waste employing a large direct shear apparatus

Abstract

ABSTRACT In this study, in order to conduct shear tests on solid waste samples encompassing waste materials of all/actual sizes (unlike many previous studies), a large direct shear device (with the capacity of 100 × 100 × 110 cm3 test samples) is designed, built, and put into practice. Disturbed (and remoulded) municipal solid waste (MSW) samples of 10 years old, taken from local landfill, are tested with shear stresses being applied under strain-controlled conditions. Two sets of tests in the form of four consolidated-drained (CD) or slow and four consolidated-undrained (CU) or quick direct shear tests are performed. The results clearly indicate that MSW, in this specific landfill, mainly show a frictional behaviour with friction angles of 31.4 (for CD/slow tests) and 38.6 (for CU/quick tests) degrees, and the cohesion values of almost zero for both sets of tests. Higher value of internal friction angle obtained from the undrained tests is attributed to the changes occurring in sample structure, texture, and composition after being completely saturated with water. These values are within the range of shear strength parameters of MSW reported in the literature. In addition, shear stress-displacement responses of all MSW samples show normally consolidated with high compressibility characteristics and strain hardening behaviour.