长期循环荷载作用下温州结构性软黏土的应变特性研究

针对软黏土存在的结构性特征，在不同围压下对天然温州软黏土进行了不排水静剪和大数目（50000次）循环加载试验，研究了结构性对土体强度的影响，并进一步分析了结构性软黏土在长期循环荷载作用下的应变特性。研究表明：围压较低时，土体的结构性在固结过程中没有或很少被破坏，软黏土表现为较高的归一化强度；随着围压的增大，归一化强度逐渐降低；当围压高于土体屈服压力时，土体结构性在固结过程中被完全破坏，此时土体的归一化强度达到稳定值，与重塑土强度相同。这种特性使得软黏土在循环加载试验中，即使在相同动应力比（mtml_13-0310_bak/img_0.png26.013.95= 0.45）下，不同围压下的应变行为也表现出明显的不同。这种区别表现在应力-应变滞回曲线、回弹特性和累积塑性应变等方面。

Long-term cyclic strain behavior of Wenzhou structural soft clay

Undrained monotonic and high-cycle loading (50000 cycles) triaxial teats are conducted on natural Wenzhou soft clay to study the influence of soil structure on the strength and cyclic strain behavior. The results show that when the confining pressure is low, the soil structure has little damage during consolidation, and the test samples exhibit higher normalized strength. With the increase of the confining pressure, the normalized strength decreases. When the confining pressure is higher than the yield pressure, the soil structure is completely damaged during consolidation, and then the normalized strength reaches a constant value, which is similar to that of remold samples. Because of this characteristic, the cyclic strain behavior of soft clay shows a clear difference with the confining pressure even keeping a constant value of mtml_13-0310_bak/img_1.png26.013.95= 0.45. The differences in stress-strain hysteresis loop, resilient behavior and permanent strain are discussed.