隧道降水施工地表沉降的渗流-应力耦合分析

SEEPAGE AND STRESS COUPLING ANALYSIS OF LAND SUBSIDENCE INDUCED BY DEWATERING AND TUNNELING

根据有效应力分析方法,建立了弹塑性渗流–应力耦合分析理论模型;采用流体体积方法方法来跟踪非稳定渗流场的动态自由水面,开发相应的数值模拟分析程序;并对某地铁隧道工程的动态降水过程和开挖过程进行仿真模拟,对降水和开挖过程中的地表沉降进行重点分析,得出动态变化的地表沉降曲线,通过将地表沉降计算值与现场量测值比较分析,两者数据吻合较好。研究结果表明,降水的影响半径约为30m,降水所引起的地表最大沉降值约为23mm,左右隧道施工完时地表最大沉降值约为43mm,施工期间周围建筑物和地下管线均无安全隐患。而通常采用30mm的控制标准,说明城市地铁工程的沉降控制基准要视具体的工程环境条件而定,这为该工程和类似工程施工提供了依据和参考作用。

Based on effective stress analysis method,the elasto-plastic model of seepage and stress coupling analysis is established,and the dynamic water table is followed by means of VOF(Volume of Fluid).The computing program of numerical simulation is developed and the dynamic process of dewatering and construction of a subway tunnel engineering are simulated with the settlement of ground surface being analyzed in details and the dynamic variation curves of ground settlement are acquired.The results by numerical simulation and in-situ measurement are coincident well.These results indicates that the influence radius by dewatering is 30 m or so,the maximum ground surface settlement induced by dewatering is about 23 mm,and the total settlement by dewatering and excavation is 43 mm.Generally the settlement criterion is 30 mm,the engineering practice that buildings and pipelines adjacent to the engineering are safe during whole construction.It shows that ground settlement control criterion on city metro engineering construction should be determined according to specific environmental conditions.The result offers theoretical basis and reference for this and similar engineering.