富水圆砾地层局部止水帷幕作用下基坑开挖变形数值分析

富水地层中的基坑止水与降水是基坑工程的重难点，大量降水易造成地表不均匀沉降。本文依托甘肃省某基坑工程利用数值模拟和现场实测的方法，研究了富水圆砾地层下排桩-旋喷桩局部止水帷幕对基坑变形的影响。在验证模型计算准确性的基础上，分析了局部有无旋喷桩、旋喷桩嵌入深度对基坑渗流与变形的影响、传统与局部止水帷幕对限制基坑变形的差异。结果表明，排桩-旋喷桩局部止水帷幕可以延长地下水渗流路径，降低渗流速度，同时分担了部分土压力，对限制地表沉降和桩身水平位移都起到了积极的作用；旋喷桩嵌入深度越深止水效果越好，并能够限制地表沉降与桩身水平位移，但超过一定深度对限制地表沉降与桩身水平位移不明显；传统止水帷幕对限制地表沉降最好，但对限制桩身水平位移效果不明显。

Numerical analysis of deformation of foundation pit during the excavation paved with local waterproof curtain in water rich gravel stratum

Water-stopping and dewatering of foundation pit in water-rich stratum are considered the key of foundation pit engineering. The uneven surface settlement is caused by a large amount of precipitation. Relying on the method of numerical simulation and field measurement in a foundation pit project in Gansu Province. Under the row of piles in the water-rich pebble stratum on the deformation of the foundation pit, the influences of the partial water-stop curtain of the jet-grouted pile are studied. Based on the verification of the calculation accuracy of the model, the influence of jet grouting pile and its embedded depth on the seepage and deformation of foundation pit is analyzed. The difference between traditional waterproof curtain and local waterproof curtain in restricting the deformation of foundation pit is studied. The results show that the partial water-stop curtain of row piles and jet grouting piles can extend the groundwater seepage path and reduce the seepage velocity. At the same time, the part of earth pressures are shared, which plays a positive role in limiting the surface settlement and the horizontal displacement of the pile. The deeper the embedded depth of the jet grouting pile, the better the water-stop effect. Meanwhile, the surface settlement and the horizontal displacement of the pile are limited. However, it is not obvious to limit the surface settlement and the horizontal displacement of the pile if it exceeds a certain depth. The traditional waterproof curtain has the best effect on limiting the surface settlement, but it has no obvious effect on limiting the horizontal displacement of the pile.