地下水渗流对基坑支护结构上水土压力的影响分析

暴雨或长时间的降雨、地下水管的渗漏等是造成地下水渗流的重要条件，对基坑支护结构的安全影响大，也是为何基坑事故多发生在降雨之后的根源。分析了基坑开挖过程中地下水渗流产生的条件，并从地下水渗流对土体强度的影响、对作用在支护结构上水压力的影响、对土体自重应力的影响3个方面进行了分析。认为地下水渗流增大了支护结构上的土压力，对于粘性土判断采用“水土合算”或“水土分算”的依据不只是土体渗透性的大小，关键在于渗流是否发生。在支护结构的土压力计算中，只要支护结构在开挖和使用阶段基坑外侧存在地下水渗流，对于粘土和粉土应当采用水土分算的计算方法。因此，在基坑工程中，预防和阻止地下水渗流的发生是相当重要的一个环节。

Effect of Groundwater Seepage on Water and Soil Pressure in Brace System of Excavation

Torrential rain, continuous rainfall and leakage of underground water pipes are important conditions that cause seepage of groundwater, resulting in high frequency of occurrence of foundation accidents. Therefore, the present study focuses on the effect of groundwater leakage on the strength of soil mass, on water pressure acting on retaining structure, and on the self- gravity tress of soil mass. Results show that not only the magnitude of soil mass' penetrability but also the groundwater leakage must be taken into account in predicting the safety of retaining structure of foundation pit no matter which calculation is used. The approach with separate calculation of water and soil should be adopted if the leakage of groundwater exists outside a constructing foundation pit.