复杂条件下基坑降水引起地面沉降预测方法
段其广
Prediction Method for Land Subsidence Induced by Foundation Pit Dewatering under Complex Conditions
DUAN Qiguang
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作者信息:中铁十四局集团大盾构工程有限公司，211800，南京
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Affiliation:China Railway 14th Bureau Group Large Shield Engineering Co., Ltd., 211800, Nanjing, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2024.12.031
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中图分类号/CLCN:P642.26
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栏目/Col:研究报告
摘要:
［目的］为研究复杂条件下基坑降水引起的地面沉降变化规律，依托南京地铁5号线机场路站深基坑项目，对基坑降水引起的地面沉降进行预测。［方法］采用现场抽水试验和理论解析的方法对基坑降水引起的地面沉降规律进行分析。分别进行单井抽水试验和群井抽水试验，通过单井抽水试验获得单井抽水引起地面沉降规律和不同地层条件下的抽水影响半径；通过群井抽水试验，获得4个典型截面的降水漏斗形状，并结合沉降固结公式推导得到适用于本工程的地面降水沉降预测公式；根据地面降水沉降预测公式计算地面降水沉降理论值，并与现场监测数据进行对比，验证地面降水沉降预测公式的适用性。［结果及结论］单井抽水影响半径随着渗透系数和降水深度的增大而增大，对于本工程的低渗透性土层其抽水影响半径约为5m，而对于高渗透性土层其抽水影响半径可达20m；降水漏斗曲线形状呈指数函数形状；距离降水井越近，地面沉降变形越大，由降水引起的地面沉降值随着距离抽水井距离的增加而迅速减小。
Abstracts:
［Objective］ To study the land subsidence variation patterns induced by foundation pit dewatering under complex conditions, the deep foundation pit project at Nanjing Metro Line 5 Airport Road Station is taken as a case study to predict the land subsidence caused by foundation pit dewatering. ［Method］ Field pumping tests and theoretical analysis are employed to analyze the land subsidence patterns induced by foundation pit dewatering. Single-well and multi-well pumping tests are conducted. The single-well pumping tests provide data on land subsidence patterns and dewatering influence radii for different soil conditions, while the multi-well pumping tests reveal the shapes of dewatering funnels across four typical cross-sections. A land precipitation subsidence prediction formula is derived using the subsidence consolidation equation tailored to the project conditions. The theoretical land subsidence values predicted by this formula are compared with field-monitored data to verify its applicability. ［Result & Conclusion］ The influence radius of single-well pumping increases with permeability coefficient and dewatering depth, reaching about 5 meters in low-permeability soil and up to 20 meters in high-permeability soil in this project. The shape of the precipitation funnel follows an exponential curve, and land subsidence deformation is greater adjacent to the dewatering well. Land subsidence induced by dewatering rapidly decreases with distance increasing from the well.
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