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饱和软土地基上长期往复交通动载将诱发显著的路基运营沉降。交通移动荷载下场地应力路径下呈现心形旋转路径,然而现有路基长期运营沉降分析是建立在循环三轴试验基础上,忽略交通移动荷载下地基土单元主应力轴的旋转效应。利用动态空心圆柱扭剪仪模拟心形循环加载路径,并在动态空心圆柱仪上模拟了传统的循环三轴加载路径。对饱和软黏土开展试验研究,对比观察一系列心形循环加载和三轴循环的不排水累计变形行为。试验研究发现,心形循环加载将诱发更大的累计轴向应变和累计孔压,伴随着初始动应力比的增加,二者差异性更为明显。循环加载过程有效动应力比随着循环次数而增大,循环增量破坏时对应的有效动应力比近似为常数。大数目循环加载下,传统塑性安定行为可渐变为循环塑性蠕变状态。
Long-term reciprocating traffic on saturated soft ground will induce significant settlement subsidence. However, the settlement analysis of long-term existing subgrade is based on the cyclic triaxial test, neglecting the rotation effect of the main stress axis of subsoil unit under traffic moving load. The heart-shaped cyclic loading path was simulated with a dynamic hollow cylinder torsion shear and the conventional cyclic three-axis loading path was simulated on a dynamic hollow cylinder. The experimental study of saturated soft clay was carried out to compare the cumulative undrained deformation behaviors of a series of heart-shaped cyclic loadings and triaxial cycles. Experimental study found that heart-shaped cyclic loading will induce greater cumulative axial strain and cumulative pore pressure, with the increase of initial dynamic stress ratio, the difference is more obvious. The effective dynamic stress ratio of cyclic loading process increases with the number of cycles, and the corresponding effective dynamic stress ratio under cyclic incremental damage is approximately constant. With a large number of cyclic loads, the traditional plastic stability behavior can be gradually changed into a cyclic plastic creep state.