考虑基坑降水中总应力与土体参数变化的渗流-地面沉降耦合模型研究

Study on the coupling model of seepage-land subsidence considering variations in total stress and soil parameters during foundation pit dewatering

为研究总应力及土体参数变化条件下基坑降水诱发地面沉降的变化机理及计算方法,以西霞院输水及灌区工程渠首倒虹吸段基坑工程为例,构建研究区地下水渗流三维数值模型。采用理论推导与实例分析相结合的方法,对基坑降水过程中的应力、参数及沉降变化进行分析对比,提出考虑总应力及土体参数变化的渗流-沉降耦合模型计算公式及方法,并对不同理论模型下地面沉降的计算结果进行对比分析。结果表明,建立的总应力与土体参数变化的渗流-地面沉降耦合模型沉降计算值最小且与实测值的拟合效果最好,可以合理解释以往研究中沉降计算值都明显大于实测值的现象,更加符合实际沉降过程。研究成果可为类似工程开展地面沉降预测提供参考和指导,具有重要的现实意义。

To investigate the mechanisms and calculation methods of land subsidence caused by foundation pit dewatering under the condition of variations in total stress and soil parameters,a three-dimensional numerical model of groundwater seepage in the study area is constructed in this research,with the foundation pit dewatering project in the head inverted siphon section of the Xixiayuan Water Conservancy and Irrigation Project as a case.The changes in stress,parameters and subsidence during the dewatering process of foundation pit are analyzed and compared by the method of theoretical derivation and case study.Calculation formula and methodology of seepage-subsidence coupling model in view of variation in total stress and soil parameters are proposed,and the calculation results of land subsidence under different theoretical models are compared and analyzed.The results show that the seepagesubsidence coupling model built in consideration of variation in total stress and soil parameters has the smallest calculation value and the best fitting effect with the measured value.This can reasonably explain the phenomenon that the calculated subsidence value is obviously greater than the measured value in the previous studies,which is more consistent with the actual subsidence process.The research outcomes are able to provide references and guidance for land subsidence prediction in similar projects,which is of great practical significance.