循环荷载作用下超固结软黏土变形特性试验研究

摘要

Cyclic triaxial tests were conducted on Wenzhou soft clay under different overconsolidation ratio (OCR) through GDS dynamic triaxial apparatus to study the effects of OCR on the strain development, stress-strain hysteresis loop and permanent strain prediction equation. Test results show that: under the same cyclic stress ratio (CSR), the aixial strain deceases with the increase of OCR, and the CSR needed to reach failure tends to decrease with the increase of OCR. With the increase of OCR, the stress-strain relation gradually translates from visco -elastic to nearly elastic because larger confining pressure is subjected for overconsolidated clay. A new permanent strain prediction equation is established based on the test results. The physical meaning and determination methods the equation parameters are discussed in the research.%利用GDS振动三轴仪对温州饱和软黏土在不同超固结比下进行了循环加载试验，研究了超固结比对温州饱和软黏土应变发展规律、应力-应变滞回曲线特征、累积应变预测方程等的影响。试验结果表明：在相同循环应力比下，超固结软黏土的应变随超固结比的增大而减小，且随超固结比的增大，使软黏土破坏所需的循环应力比呈现出减小的趋势。由于超固结土先期承受了较大的固结压力，随着超固结比的增大，软黏土的应力-应变关系逐渐由粘弹性转变为近似弹性特征。基于不同超固结比下的试验结果建立了累积应变预测方程，阐述了方程中各参数的物理意义及确定方法。