地震荷载下水泥土循环剪切特性研究

Study on cyclic shear characteristics of cement-soil under seismic loading

基于地震荷载下水泥土桩复合地基的破坏机制,采用GDS动单剪仪对水泥土进行动力循环剪切试验,研究水泥掺入比与循环应力比对水泥土动变形、动强度以及软化特性的影响。试验结果表明:水泥掺入比的增加会减缓水泥土动剪应变的发展而动强度则逐渐增强,但循环应力比反之;水泥掺入比为5%,10%,15%的水泥土临界循环应力比分别为0.267,0.286,0.327。通过采用转折应变作为水泥土破坏的标准和数据归一化处理方法,建立了循环应力比和破坏振次的模型。循环荷载作用下,随着循环应力比与循环振次的增大,水泥土的软化指数将减小,半对数模型能够较准确描述水泥土的软化特性。

Based on the failure mechanism of cement-soil pile group under seismic loading,the dynamic cyclic shear tests of cement-soil were carried out by using GDS dynamic simple shear apparatus to study the effect of cement ratio and cyclic stress ratio on dynamic deformation,dynamic strength and degradation characteristics. The results indicated that the dynamic shear strain developed more slowly and the dynamic strength was gradually increased with the cement ratio increasing. However,the results of the increase of cyclic stress ratio were opposite. It was shown that the critical cyclic stress ratios were 0.267,0.286 and 0.327 for the cement-soil with cement ratio of 5%,10% and 15%,respectively. Using the failure criteria of turning strain and the method of normalization,the model between cyclic stress ratio and failure number was established. The degradation index of cement-soil reduced with the increase of cyclic stress ratio and cyclic number under cyclic loading,and the Semi-logarithmic model could more accurately describe the degradation characteristics of cement-soil.