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针对青岛地铁中山公园暗挖岩石车站开挖出现地表变形过大问题,结合现场施工监测动态信息,采用有限元方法模拟了车站在各施工开挖步后产生的地表沉降、洞室收敛变化情况。结果表明,原设计方案车站地表沉降达50 mm左右,洞室直墙处收敛值较大,车站整体有塌陷的可能,实际监测地表最大沉降为45 mm,与模拟值较为吻合。施工中掌子面穿过断面一定距离后,该断面地表沉降速率变小,表明支护结构的施作对地表沉降起到了一定的控制作用。提出了加强支护控制过大变形方案优化方法,对修改后的支护设计方案数值模拟表明,采用新设计方案的车站地表沉降量减少44%,最大地表沉降为28 mm,且中导洞开挖引起的位移沉降量占总沉降的60%左右,能保证地表变形控制在允许安全范围内。
Aiming at the problem of excessive deformation of ground surface during the excavation of underground excavation station of Zhongshan Park in Qingdao Metro and the dynamic information of site construction monitoring, finite element method is used to simulate the surface settlement and cavern convergence caused by excavation steps of each station. The results show that the original design scheme is that the ground surface settlement of the station is about 50 mm, the convergence value of straight wall of the tunnel is large, and the overall collapse of the station is possible. The maximum settlement of the ground surface actually monitored is 45 mm, which is in good agreement with the simulation value. After the construction plane passes through the cross section for a certain distance, the subsidence rate of the cross section becomes smaller, indicating that the application of the retaining structure has a certain control effect on the ground subsidence. The optimization method of strengthening the deformation control scheme is put forward. The numerical simulation of the modified support design shows that the ground surface settlement of the station with the new design scheme is reduced by 44% and the maximum ground surface settlement is 28 mm. The displacements caused by displacements account for about 60% of the total settlement, which can ensure the control of deformation of the ground surface within the allowable safety range.