超固结软黏土的静止土压力系数与不排水抗剪强度

Coefficient of earth pressure at rest and undrained shear strength of overconsolidated soft clays

通过应力路径三轴试验对不同超固结比下饱和软黏土的K_0系数及K_0超固结软土的抗剪强度进行了研究,提出了超固结软土的K_0系数计算公式,基于各向异性屈服准则推导了K_0超固结软黏土的不排水抗剪强度,并与试验结果对比证明了计算公式的有效性。分析表明,常用的Mayne-Kulhawy K_0系数计算公式过高地估算较大超固结比OCR时的K_0系数,同时所提出的K_0超固结软黏土不排水抗剪强度公式通过考虑土体K_0系数随OCR的变化,避免了假设以有效上覆压力表示的回弹线斜率为常数所存在的问题。通过与试验结果对比表明,该公式能较好地预测K_0超固结土体的不排水抗剪强度。

The stress path triaxial tests were conducted to examine the coefficient of Ko of different stress paths and the undrained shear stress-strain under K0-conlidation. Formula of K0 coefficient was proposed for Ko overconsolidated soil. Based on anisotropic yield criteria, the undrained shear strength equations of K0 overconsolidated soil were developed. The validity of proposed procedure was verified by comparing calculated results and experimental results. The results indicated that the formula proposed by Mayne and Kulhawy overestimated the coefficient when the OCR was large. The undrained shear strength equations of K0 overconsolidated soil avoided errors which were caused by assuming a constant slope of rebound denoted by the effective overburden pressure, by considering the variation of K0 coefficient with OCR. Experimental results indicated that the proposed formula has the advantage to predict the undrained shear strength of K0 overconsolidated soil.