循环荷载对海相粉土力学特性的影响

Effect of Cyclic Load on Mechanical Properties of Marine Silt

为研究波浪等循环荷载对海相土物理力学特性的影响,利用GDS三轴仪对杭州湾区域重塑海相粉土进行了一系列不排水静三轴和循环后静三轴试验,分析围压、循环应力比、循环次数等因素对粉土循环及循环后力学特性的影响,构建循环扰动与粉土不排水强度之间的关系。结果表明:循环荷载作用下,粉土累积应变随循环次数的增加表现出稳定或快速发展的临界现象。残余孔压会改变试样循环后剪切阶段的剪胀性。循环加载会导致杭州湾海相粉土的不排水强度Su出现衰退,且衰退程度与残余应变和残余孔压比均有关联。最后,基于试验数据建立了预测残余应变和不排水强度比关系的公式。

In order to study the influence of cyclic load on the physical and mechanical characteristics of Marine soil,u-sing GDS triaxial apparatus,a series of static and cyclic-static undrained triaxial compression tests on remolded silt sam-ples in Hangzhou bay were carried out,and the influences of confining pressures,cyclic stress ratio and cycle times on the undrained behaviors of the silt were studied,and the relationship between cyclic disturbance and the undrained strength of silt was established.The results show that,the pore pressure and strain increase with the increase of cyclic stress ratio and cycle times.Under cyclic loading,the cumulative strain of silt shows a critical phenomenon of stabilization or rapid devel-opment with the increase of the cycles number.The residual pore pressure will change the shear dilatancy of the specimen.Cyclic loading can cause the strength of Hangzhou Bay marine silt to decrease,and the degradation is correlated with both residual strain and residual pore pressure ratio.Finally,based on the experimental data,the fitting relationship between re-sidual strain and undrained strength was established.