考虑侧向变形的各向异性砂土土压力试验研究

EXPERIMENTAL STUDY OF EARTH PRESSURE FOR ANISOTROPIC SAND CONSIDERING LATERAL DISPLACEMENT

基于各向异性砂土在不同常应变增量比条件下的应变路径试验研究土压力系数与侧向应变约束条件之间的密切关系,并且进行各向异性砂土的土压力离心模型试验,验证材料试验的规律,分析比较大主应力与沉积面夹角不同时填土的土压力及位移场随挡墙位移变化规律的异同。研究结果表明,大主应力分别垂直和平行于沉积面的2种情况下,K0状态附近的滑动区域差别较小,土压力大小差别较小。随着挡墙位移的增大,2种情况下填土形成的滑楔体大小和土压力大小的差异明显增大,大主应力垂直于沉积面时填土中形成的滑楔体尺寸较小,土压力也相对较小。试验结果表明,与各向同性的情形相比,各向异性使静止状态的土压力增大,对极限状态影响较小,表明压缩变形各向异性明显比强度各向异性影响要大。

Strong dependence of earth pressure coefficient on lateral strain constraint is investigated by strain path tests of anisotropic sand under different constant strain increment ratios. In addition, centrifuge model tests for earth pressure are conducted to vertify the rules of material test. On the basis of centrifuge model test results, variation of earth pressure and displacement field of the backfill with wall movement is compared and analyzed for anisotropic soil with different particle orientations. It is shown that for the two cases in which the maximum principal stress acts perpendicular to and parallel with the bedding plane, the difference of the sliding mass and the earth pressure is small when the backfill is near the K0 state. While it becomes larger with the increase of wall movement. The sliding mass and the earth pressure are relatively smaller when the maximum principal stress is perpendicular to the bedding plane. In comparison with the isotropic case, anisotropy can increase the earth pressure at rest; but it has little effect on the earth pressure at the limit state, indicating that the effect of compression anisotropy is obviously stronger than that of strength anisotropy.