中文摘要：

随着循环次数的增加，循环荷载作用下正常固结软黏土孔隙水压力逐渐增加，而孔压的增加将导致土体发生软化现象。对于超固结软黏土，循环荷载作用下在循环初期将产生负孔压，而此时也发生循环软化现象，这显然与有效应力原理是相矛盾的。以往的研究往往通过建立软化指数与循环次数的关系来描述土体的循环软化特性，从而不能反映土体的循环过程中残余孔压变化对土体循环软化的影响。通过对杭州饱和软黏土进行应力控制的循环三轴试验，对循环荷载作用下超固结软黏土的软化特性及孔压发展规律及两者关系进行了研究。在试验的基础上建立了超固结软黏土循环软化-孔压模型，该模型反映了残余孔压增长对超固结软黏土循环软化特性的影响规律。

英文摘要：

Softening phenomena will occur in normally consolidated soft clay under cyclic loading because of the increase of pore pressure with progressive cycle number. However, in overconsolidated soft clay, negative pore water pressures may develop at the beginning of cyclic loading, despite the fact that softening phenomena occurs simultaneously. It is evident that this behavior is contradictory to the effective stress principle. In addition, the preceding approach to cyclic softening characteristic of cohesive soils is to establish the relation between softening index and cycle number which doesn＇t encompass the pore water pressure generation that occurs simultaneously. The residual pore water pressures correlate to softening index of overconsolidated clay subjected to uniform stress-controlled triaxial loading are investigated. A cyclic softening-pore pressure model is proposed based on the tests. The model shows the influence law of cyclic softening characterstic of overconsolidation.