临河富水砂卵石层深基坑降水方案分析

Analysis on Dewatering Scheme of a Deep Foundation Pit in Watery Sand-gravel Ground near a River

对于临河深基坑,临河侧地下水控制是基坑设计的关键问题。针对某临河富水砂卵石层深基坑工程,分别采用《建筑基坑支护技术规程》(JGJ 120—2012)、《管井技术规范》(GB 50296—2014)和临河基坑涌水的理论公式进行降水方案设计,并采用地下水渗流数值方法辅助计算,优化了临河基坑降水的设计方案。根据《建筑基坑支护技术规程》《管井技术规范》降水计算结果,基坑管井间距为20 m,然而工程实践中发现基坑靠近河流侧出现了积水。结合临河基坑的理论公式和典型管井段的数值模拟结果,优化靠近河流侧的基坑降水方案,确定基坑靠河流侧的管井井距在9~10 m,并据此成果在沿河侧新增了13个降水管井,解决了临河侧基坑积水问题。

For deep foundation pit near a river,groundwater control is crucial for the foundation pit design.Based on a deep foundation pit in watery sand-gravel ground near a river,the dewatering scheme was discussed by technical specifications in JGJ 120—2012,GB 50296—2014 and theoretical formula on foundation pit near a river.The numerical method of groundwater seepage was also used to assist the optimal design of the dewatering scheme.According to the calculation results of JGJ 120—2012 and GB 50296—2014 technical specification,the distance of tube well was 20 m.However,it was found that water accumulated in the foundation pit near the river in the engineering practice.Combined with the theoretical formula of foundation pit along river and the numerical simulation results,the reasonably well spacing should be between 9 m and 10 m.According to research result,the problem of water accumulation in the foundation pit was solved by adding 13 tube wells.