原状黄土地基渗水特性及其与自重湿陷的关系研究

通过青海乐都大厚度自重湿陷性黄土地基现场试坑浸水试验,深入研究了原状黄土地基湿陷特性及渗水特性两个核心问题。通过分层布设沉降观测系统和TDR水分原位测试系统,对试坑浸水试验过程及停止浸水后原状黄土地基不同位置的体积含水率和沉降进行连续观测。精确测试了水在原状黄土地基中的入渗过程、扩散形态及长时间浸水条件下的影响范围;得到了水在原状黄土地基竖向和径向不同部位的扩散速率及其与扩散距离之间的关系;分析了水分入渗与自重湿陷变形之间的相互关系;提出了用现场实测的黄土受水浸湿时间和湿陷起始时间之间的时间差定量判定黄土自重湿陷敏感性的新方法及其评价标准建议值。

Seepage characteristics and their relationship with self-weight collapse of intact loess ground

The characteristics of collapse and seepage of loess are studied through in-situ pit flooding tests in Ledu County, Qinghai Province of China. The continuous observation during and after flooding of intact loess ground using the settlement and in-situ TDR water content measurement systems reveals the seepage pattern and its effect on the self-weight collapse of loess, particularly, the temporal-spatial distribution of seepage in intact loess foundation is well recorded. Based on TDR water measurement detectors, the seepage process and seepage pattern of water in intact loess foundation are precisely measured to obtain the velocity of dispersion and its changing both vertically and horizontally at different stages of flooding tests, and the relationship between velocity and distance of water dispersion is established. Further analysis reveals the relationship between water seepage and self-weight collapse of loess. Based on this observation, a method to evaluate the susceptibility of self-weight of loess is proposed by calculating the time difference between the seepage front and commencement of self-weight collapse of loess.