Cyclic Shear Response of Fraser River Sand Using Cyclic Ring Shear

摘要

Cyclic triaxial, direct simple shear, torsional shear, resonant column, and cyclic ring shear apparatuses have been used for evaluating cyclic shear strength and liquefaction resistance of cohesionless soils. In this study cyclic shear response of Fraser River sand is investigated using constant-volume cyclic ring shear tests. The effects of sample preparation method, vertical stress, number of loading cycles to liquefaction (N_L), cyclic stress ratio (CSR), and relative density (D_(rc)) on the liquefaction behavior of Fraser River sand are investigated. Fraser River sand specimens are prepared by different sample preparation methods and tested under stress-controlled, constant-volume, plane-strain shearing condition. The ring shear specimens are consolidated to vertical stresses of 100, and 200 kPa prior to the application of uniform, sinusoidal, shear stress cycles. The specimens are then subjected to cyclic shear stress ratios (CSR) of 0.08, 0.10, 0.12, 0.15 and 0.20. Cyclic shear strain and effective vertical stress respectively increase and decrease with increasing the number of loading cycles. Larger cyclic shear strains and greater reductions in effective vertical stress are also produced at higher CSR. It is found that saturated water-pluviated samples exhibit significantly higher cyclic shearing resistance compare to dry air-pluviated and saturated moist-tamped samples. Compared to cyclic direct simple shear tests, cyclic shearing resistance measured in ring shear experiments is higher due to the rigid boundaries of the specimen chamber which impose a perfect plane strain shearing condition.