成都地铁车站深基坑周围地表沉降规律研究

A study of the land subsidence around the deep foundation pit of the Chengdu subway station

采用颗粒离散元法,分析成都地铁卵石地层深基坑开挖过程中周边地面沉降的变化规律;收集了成都地区9个地铁车站深基坑周围地表沉降的监测资料,给出了地面沉降的包络线及其数学表达式;对比成都地区卵石地层深基坑与上海地区软土地层深基坑周围地表沉降包络线,总结了两者的异同。结果表明:成都地铁卵石地层深基坑周围地表沉降曲线呈凹槽型,沉降包络线可由3段直线组成,其最大沉降点位于坑壁外0.25H处,突变点位于坑壁外0.5H处;成都卵石地层深基坑的地表沉降包络线在地表范围、最大沉降点及突变点距坑壁的距离等均约为上海软土地层深基坑的1/2,两者的最大沉降值可相差1个数量级。

The land subsidence varying with the excavation of the Chengdu subway deep foundation pit in the cobble stratum was analyzed with the granular discrete element method. The monitoring data of the land subsidence around the deep foundation pits of nine subway stations in Chengdu were gathered. The land subsidence envelope curve and its mathematical expression were also given. By comparing the land subsidence around the deep foundation pit in the soft stratum in Shanghai with that in the cobble stratum in Chengdu,the similarities and differences were summarized. The results show that the land subsidence curve of the Chengdu subway deep foundation pits in the cobble stratum belongs to a groove type. Its envelope curve is made up of three beelines. The maximal point of the envelope curve locates at the 0. 25 H place behind the foundation pit,and the mutation point locates at the 0. 5H place,where H is the excavation depth. The ground scope of the envelope curve in the Chengdu cobble stratum is about 1 /2 that of the Shanghai soft stratum. So are the distance from the maximal point to the foundation pit and that from the mutation point to the foundation pit.Both of the maximal subsidence values in the Chengdu cobble stratum and in the Shanghai soft stratum are different by 1 order of magnitude.