分离岛式地铁车站交叉洞群施工的周边环境效应分析

为研究分离岛式车站交叉洞群的周边环境效应,以广州市某暗挖地铁车站为工程背景,采用数值模拟的分析方法,建立了正线隧道、联络通道和站台横通道的多洞室数值计算模型,同时考虑左右线隧道穿越不同岩性的地层,有限元模型地层为不均匀地层。通过数值模拟研究了隧道交叉洞群施工引起的地表沉降、围岩应力应变特征、支护变形受荷规律等,并将模拟结果与相应的现场监测数据对比分析。计算结果表明：中洞施工会引起围岩应力场位移场重分布,上覆围岩会向两侧滑动,造成洞间土体呈受压状态,侧洞会向两侧位移；支护结构最大应力值出现在隧道与联络通道的接口处,并且隧道支护结构应力值大小与距交叉段远近成负相关,离交叉段越远,支护应力值越小。研究成果为今后类似工程条件下城市地铁隧道施工提供参考。

Study on surrounding environmental effects of intersecting tunnels group construction of separate island station

In order to study the surrounding environmental effects of intersecting tunnels group construction of separate island station, taking the underground excavation station in Guangzhou as the engineering background, this paper uses the finite element method and establishes the numerical calculation model of the main line tunnel, connecting channel and the platform transverse channel. Considering that the left and right lines tunnels pass through the strata with different lithology, the strata of the finite element model are uneven strata. It studies the surface settlement, the stress-strain characteristics of surrounding rock and the loading law of support deformation caused by the construction of intersecting tunnel group, and the numerical simulation results are compared and analyzed with the measured values on site. The calculation results shows that the construction of the middle of the tunnel will cause the redistribution of the displacement field of the surrounding rock stress field, and the upper surrounding rock will slide to both sides, resulting in the compression of the soil between the tunnels, and the two side chambers will move to both sides. The maximum stress value of the supporting structure appears at the interface between the tunnel and the contact channel, and the stress value of the supporting structure is negatively correlated with the distance from the intersection, farther the distance to the intersection,the smaller the supporting stress value is. The research results can provide reference for the construction of urban subway tunnels under similar engineering conditions in the future.