结合上海某地铁隧道穿越地面既有严重倾斜危房的工程实例,计算分析盾构穿越引起的施工期沉降、后期固结沉降及其对房屋的影响。基于地铁运营期间列车循环振动对隧道周边土性及孔隙水压的影响测试规律,提出地铁运营期列车长期振动下沉降的实用估算方法,预测分析地铁运营期列车振动引起的长期沉降。在此基础上制定相应的建设期施工对策,并提出地铁运营期四阶段维护控制设想,对当前形势下的软土地区地铁建设与运营具有现实指导意义。计算结果同时表明,地铁振动导致的长期沉降中约80%发生在隧道建设后10a内,因此这10a是采取措施的关键时期。
In connection with the practice of a metro tunnel crossing below ground buildings in Shanghai soft soils, the transient and consolidation settlements of the severely inclined building induced by two shield tunnels crossing one after another are analyzed with respect to their distribution and time-dependant features. Furthermore, based on field measurement data of pore water pressure and laboratory experiment on soil behavior under vibration, an estimation method for settlement induced by long-term train vibration during metro operation is proposed to predict the effect on ground buildings. The final settlement concerning both construction and operation stages varies with time and relative position to the tunnel center. These changing features of settlement are in close relation with the damage criterion of building and significantly affect the safety of the building. According to the time and space-dependant features of settlement during construction and operation stages of metro tunnel, corresponding measures for four different stages are suggested to control the settlement effectively. The calculation results of long-term settlement induced by train vibration show that about 80% of the total settlement occurs during the first decade, which indicates that the first decade is the key period to take measures to control settlement.