人工制备湿陷性黄土地基地下连续墙浸水试验研究

为研究湿陷性黄土地基地下连续墙基础竖向极限承载特性及浸水后负摩阻力分布特征,选用石英粉、砂、膨润土、石膏和工业盐制备了人工湿陷性黄土,对人工制备湿陷性黄土的物理力学特性进行分析;采用人工制备湿陷性黄土填筑模型试验,进行地下连续墙基础承载特性试验研究。研究结果表明:人工制备湿陷性黄土的物理力学参数与天然黄土基本一致,可用于湿陷性黄土与构筑物相互作用模型试验相似材料。地下连续墙竖向承载力达到其极限时,外墙和内墙总侧摩阻力荷载分担比为67%,确定地下连续墙为端承摩擦型基础。地基浸水湿陷后,中性点深度比为0.64~0.73,试验结果与桩基浸水试验测试结果较为一致。由于地下连续墙基础具有良好的整体性和防渗性,芯土不受水的影响,内墙侧摩阻力与承台土反力能够得以发挥,有效减小地下连续墙基础的沉降。

Soaking test on underground diaphragm wall in artificially prepared collapsible loess foundation

The tests on the bearing behavior of diaphragm wall foundation are conducted to study the vertical ultimate bearing capacity of diaphragm wall and distribution characteristics of negative skin friction after water immersion in collapsible loess foundation. The artificial collapsible loess is prepared by using quartz powder, sand, bentonite, gypsum and industrial salt, and its physical and mechanical properties are analyzed. The tests on the bearing capacity of diaphragm wall foundation are carried out with the artificially prepared collapsible loess as the model filling soil. The results show that the physical and mechanical parameters of artificial loess have a high coherence with those of natural loess, which can be applied to the model tests on the interaction between collapsible loess and structure as similar materials. The total load sharing ratio of side frictional resistance for outer wall and inner wall is 67% as the vertical bearing capacity of the diaphragm wall reaches its limit, which comes to the conclusion that the diaphragm wall is a kind of end-bearing friction foundation. After foundation soaking, the depth ratio of neutral points ranges from 0.64 to 0.73, which is in good agreement with the test results of soaking tests on pile foundation. The core soil is not influenced by water because the diaphragm wall foundation has good integrity and anti-permeability, which exerts side friction of inner wall and reaction force of bearing-stage soil and reduces the foundation settlement of diaphragm wall effectively.