大坡度小曲率盾构施工对既有地铁隧道的影响

Influence of Shield Construction on Existing Subway Tunnel with Large Slope and Small Curvature

本文研究大坡度小曲率半径隧道盾构施工过程导致的既有隧道变形问题。以郑州某延长线隧道大坡度小曲率半径下穿既有隧道为工程背景,采用三维有限元方法,建立了大坡度小曲率隧道盾构下穿施工前、穿越中、穿越后及完全穿越4种工况下的计算模型。研究分析发现:随着盾构施工的推进,地面沉降及隧道沉降值逐渐增大。既有隧道断面底部沉降最大,顶部沉降最小,同时由于新建隧道坡度和曲率的影响,两侧沉降呈现出不对称的情况,产生一定的扭转效应。在完全穿越前,由于隧道坡度和曲率的影响,导致的隧道断面沉降出现不对称的情况,靠近盾构掘进方向的位置处隧道沉降更大,施工中应提前对隧道底部和两侧进行监测。穿越完成后,呈现出一定的对称性,扭转效应基本消除,但由于坡度的影响,隧道两侧沉降峰值位置有所差别。研究成果对于施工安全与施工监控具有重要的借鉴意义。

The existing tunnel deformation caused by shield construction process of large slope and small curvature tunnel is studied.Based on the engineering background of a tunnel with large slope and small curvature radius passing through the existing tunnel of an extension line in Zhengzhou,the three-dimensional finite element method is adopted to establish the calculation models under four working conditions:before construction,during construction,after construction and complete tunnel passing through.The results show that the ground settlement and tunnel settlement increase gradually with the advance of shield construction.The settlement at the bottom of the existing tunnel section is the largest,while the settlement at the top is the smallest.At the same time,due to the influence of the slope and curvature of the new tunnel,the settlement on both sides presents an asymmetric situation,which produces a certain torsional effect.Before the complete crossing,due to the influence of tunnel slope and curvature,the settlement of tunnel section is asymmetrical,and the settlement of tunnel near the direction of shield tunneling is larger,so the tunnel bottom and both sides should be monitored in advance during construction.After crossing,there is a certain symmetry,and the torsional effect is basically eliminated,however,due to the impact of slope,the settlement peak position on both sides of the tunnel is different.The research results have important reference significance for construction safety and construction monitoring.