사질지반에서 액상화 저항에 대한 선행전단응력의 영향

초록

SYNOPSIS : Cyclic simple shear tests were performed to find out the effect of preshear on dynamic strength of the sandy soil. Tests were performed for the specimens, prepared by dry tamping method, with 40% and 60% of relative density, under three different effective confining pressures of 50, 100 and 200kPa. Under 50 and 100kPa with preshear ratios 0.00, 0.08, 0.12 and 0.16, respectively. For low and high relative densities, two different results are shown in dynamic tests. Under the dense conditions, the maximum shear stress ratio() and the cycle shear stress ratio() causing a certain shear strain increase with augmenting preshear ratio(). However, the maximum shear stress ratio and the cycle shear stress ratio causing a certain shear strain increase or decrease with increasing preshear ratio under the loose conditions. Correction factor() for preshear increases at an early stage and then decreases with increasing preshear ratio at loose condition and increase with increasing preshear ratio at dense condition. The value depends on the effective confining stress so that increase with the increasing confining stress. Correction factor() for preshear increases with the increasing preshear ratio irrespective of relative density.