受承压水作用的基坑底板临界厚度的确定方法

分析了承压含水层补给区水位上升时承压含水层上基坑底板土层孔隙水压力和有效应力的变化规律。根据基坑底板土的渗透性及其破坏机制,基于弹性力学理论,按受弯拉裂破坏模式和剪切破坏模式计算确定基坑底板土层临界厚度,通过算例和分析,与传统确定临界厚度的计算方法进行了对比。研究表明,提出的基坑底板土层临界厚度的确定方法能考虑土的抗剪强度指标cu和?u以及底板尺寸的影响,比传统计算方法更合理。然而,对于如砂土这类强渗透性土而言,文中方法求解的结果可退化为传统方法的解。

A method for determining critical thickness of base soil of foundation pit subjected to confined water

The change of pore water pressure and soil effective stress in foundation pit base, subjected to fast increase of confined water pressure due to sudden rise of the influent river during flood peak, have been analyzed. Based on soil permeability and its two damage mechanisms (i.e. tensile failure and shear failure), a new method for determining critical thickness of base plate of foundation pit is presented based on elastic theory. The new method is compared with traditional method to calculate the critical thickness of base soil of foundation pit by case study. Results show that the new method considering indices cu, ?u, and the size of foundation pit base, is more reasonable than the traditional method. However, the results calculated by the method in this paper reduce to the results by traditional method as for highly permeable soil like sand.