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复杂城市环境条件下深大基坑工程降排水所引发的地面沉降问题日益突出,针对地面沉降的控制措施已引起普遍关注。本文采用考虑饱和土流固耦合的有限元方法建立深基坑工程的二维分析模型,模拟深基坑施工的降水开挖过程,研究深厚承压含水层中止水帷幕深度和坑外地下水回灌等措施对地面沉降的影响规律。结果表明,加深止水帷幕和加大回灌量均可以有效地减小基坑外的水位变化,控制降水开挖引发的坑外地面沉降。止水帷幕深度超过抽水井深度10 m时,止水帷幕的控制作用最优;回灌量至少达到抽水量1/5,回灌才会对地面沉降有较明显的影响。
The problem of land subsidence caused by desilting of deep foundation pit projects under complex urban environmental conditions has become increasingly prominent. Control measures for land subsidence have drawn widespread attention. In this paper, a two-dimensional analytical model of deep foundation pit engineering is established by means of finite element method considering the fluid-structure interaction of saturated soil. The process of rainfall excavation during deep foundation pit excavation is simulated, the depth of water-stop curtain in deep confined aquifer and the groundwater recharge And other measures on the impact of land subsidence law. The results show that deepening the water curtain and increasing the amount of recharging can effectively reduce the water level outside the foundation pit and control the settlement of the ground surface caused by the excavation. When the depth of water curtain exceeds 10 m, the control effect of water curtain is optimal. When the amount of water return is at least 1/5 of that of water pumping, the recharge will have a significant effect on land subsidence.