水平双向荷载耦合对饱和软黏土动力特性的影响

Effect of horizontal bidirectional coupled loads on dynamic properties of saturated soft clay

地震过程中剪切波可用大小和方向上相互耦合的水平两向剪切来模拟。以温州典型软黏土为对象,采用多向动单剪系统(VDDCSS)进行不排水应力控制的循环单剪试验,重点研究了水平双向耦合荷载作用下循环剪应力比(SSR)和相位差?对饱和软黏土动力特性的影响,试验组数共计19组。试验结果表明:在单向循环剪切荷载作用下温州正常固结饱和软黏土的门槛循环应力比SSR_(x,menkan)为0.096,临界循环应力比SSR_(x,limit)为0.15;水平双向耦合荷载作用下,双向循环应力比SSR(SSR_x(28)SSR_y)的提高以及循环次数N的增加会促进剪应变?的增加和孔压u的发展;当SSR稍微大于SSR_(x,menkan)时,?的增加也会阻碍?和u发展,在临界循环应力比SSR_(x,limit)附近,?的存在会急剧加快土样总应变和孔压的发展,当SSR>SSR_(x,limit)时,相位差?的存在对土样总应变和孔压发展的影响基本可以忽略。

During earthquakes, the shear wave can be simulated by the horizontal bidirectional shear stresses mutually coupled in magnitude and direction. To investigate the influence of cyclic shear stress ratio（SSR） and phase differenceq on dynamic characteristics of soft clay under bidirectional loading, 19 groups of undrained cyclic simple shear tests have been performed on typical Wenzhou soft clay by using multi-direction cyclic shear apparatus. The test results show that the threshold cyclic stress ratio SSR_x,menkan for the typical Wenzhou soft clay under unidirection cyclic shear loading is 0.096 and the critical cyclic stress ratio SSR_x,limit is 0.15. Under the bidirectional cyclic shear loading, the increase of cyclic number N and the improvement of SSR will promote the development of shear straing and pore pressure u. When SSR is slightly larger than SSR_（x,menkan）, the increase of q will decrease the development of g and u. When SSR is between SSR_（x,menkan） and SSR_（x,limit）, shear straing and pore pressure u increase rapidly with the increase of q. When SSR is larger than SSR_（x,limit）, the effect of phase differenceq on the shear straing and pore pressure u can be ignored.