天然沉积结构性黏土原位压缩规律及预测模型研究

通过天然沉积黏土的原状样与重塑样的压缩对比试验，揭示了屈服后土结构性的渐进性破损过程以及由常规 曲线确定的压缩指数 随固结压力呈非线性变化性状给实际工程沉降计算参数选取带来不便。采用 双对数坐标表示方法，通过不同初始结构大小的黏土试验数据证实了 压缩曲线在屈服前后段具有良好的线性关系，实现了结构屈服应力、屈服前后压缩指标有效统一确定。在该坐标体系下给出了考虑取样扰动影响的原位压缩曲线恢复方法，建立了结构性黏土的双线性压缩模型，结合文中与文献中试验数据给出了结构屈服应力与不排水强度、屈服后压缩指标与稳定指数SI和液限wL的经验关系。研究结果可为天然沉积土地基固结沉降计算参数的合理选取提供依据。

In-situ compression law and prediction model of natural sedimentary structured clay

The comparative compression tests were performed on the natural sedimentary undisturbed clays and corresponding remolded samples. The test results indicate that the destructuration after gross yield is a progressive process; the post-yield compression curve displays a nonlinear behavior in the plot of ; and the compression index, Cc, designated by the slope of the curve, is not constant in the entire stress range, which cause trouble to settlement calculation. Therefore, the double logarithmic coordinates system is used to represent the compression curve. A good linear relationship between the logarithm of the specific volume and logarithm of consolidation stress is obtained for clays with different initial structures. The soil structural yield stress and compression indices in the pre-yield and post-yield phases are effectively and simultaneously determined. And then taking into account the sample disturbance, a method of modifying the compression parameters is presented to predict the virgin compression curve; and a bilinear compression model is developed for the structured clays. Based on the experimental data in this paper and other literatures, the empirical relationship between the yield stress and undrained strength, and relationship between compression index and stability index (SI) as well as liquid limit (wL) are established. This study results provides a reasonable basis for determining the consolidation and settlement calculation parameters.