考虑渗流影响的软土管幕箱涵开挖面稳定分析
Stability of excavation face in soft soils by roof-box jacking method considering seepage
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摘要: 管幕箱涵工法可以有效减小施工对地面交通的影响,适用于城市密集空间条件下的地下穿越工程。通过引入开挖面前方水头分布拟合公式,提出了考虑渗流影响的管幕箱涵开挖面稳定性极限平衡法,并对该极限平衡法进行了算例和工程实例的有限元模拟验证。极限平衡法计算结果和算例及实际工程案例的有限元模拟结果较为一致,验证了本文极限平衡法的合理性和有效性。研究发现,地下水渗流会对管幕作用下的箱涵开挖面稳定产生较大影响,维持开挖面稳定的极限支护压力远大于无地下水作用的情况,在实际工程中应考虑地下水渗流的影响。Abstract: The roof-box jacking method can significantly reduce the impact of construction on ground traffic. It is suitable for underground engineering under the dense urban space. The limit equilibrium method for the stability of excavation face with pipe curtain considering seepage is proposed by introducing the fitting formula for distribution of water head in front of the excavation face. The new method is verified through finite element simulations of examples and an actual project case. The results by the proposed method are in consistent with those by the finite element simulations, which verifies the rationality and effectiveness of the method. The analysis shows that the seepage has a great influence on the stability of the excavation face with pipe curtain, and the limit support pressure to maintain the stability of the excavation face is much greater than that without considering groundwater. The influences of seepage should be considered in practical projects.