不同循环荷载作用下软黏土动力特性对比试验研究

研究交通循环荷载作用下路基软黏土的长期沉降和动力力学性质对路基设计具有重要意义。本文通过GDS动三轴实验,研究(不排水条件下)振动波形、排水条件以及动应力比三因素对于软黏土动应变和动孔压的影响。试验结果显示:排水条件对饱和软黏土的动应变和动孔压影响最大,在部分排水条件下动孔压逐渐消散,动应变迅速发展。振动波形对软黏土动应变和动孔压影响较大,单向纯压半正弦波作用下软黏土的动应变和动孔压较容易达到最大值。在较少的振次内动应力比对孔压影响较大,但在归一化的孔压模型中,动应力比对孔压影响较小。通过以上分析,本文建立包含循环振次和纯压因素的孔压增长模型。

Comparative Experimental Study on Dynamic Characteristics of Soft Clay under Different Cyclic Loads

Investigation of long-term settlement and dynamic mechanical properties of soft clay under cyclic loads is important to its subgrade design. In this study, we determined the effects of vibration waveform, drainage condition, and dynamic stress ratio on the dynamic strain and dynamic pore pressure of soft clay under undrained condition through GDS dynamic triaxial test. Results show that the drainage condition exhibits the most serious influence on the dynamic strain and dynamic pore pressure of saturated soft clay. Under the condition of partial drainage, the dynamic pore pressure gradually dissipates and the dynamic strain develops rapidly. The vibration waveform also influences the dynamic strain and pore pressure of soft clay, and these parameters easily reach the maximum value under the action of unidirectional pure pressure semi-sine wave. The dynamic stress ratio has a great effect on pore pressure under few vibration times. However, the dynamic stress ratio minimally affects pore pressure in the normalized pore pressure model. Through the above analysis, a pore pressure growth model including the indices of cyclic vibration time and pore pressure, was established.