Study On Control Measures Of Ground Settlement Due To Subway Station Excavation By Shallow Mining Method

With the development of economic, subway has become more and more important for its large freight volume, low energy consumption and low pollution. Generally located at the busy zone of city, it always leads to cracks, inclination or underground pipeline rupture if there is settlement accident in urban metro. Therefore there is much practical significance to study the law of settlement and put forward measures of settlement control.This thesis is on the background of Xiaobei station in Guangzhou subway, with the use of FLAC^3D, the excavation methods, excavation sequence in multi-tunnel system, settlement effect caused by ground water, etc are studied and the measures of settlement control are proposed.First, according to the characteristic of ultra-shallow and large section of the west hall in Xiaobei station ,six simulation schemes are proposed ,of which the best one is chosen through surface settlement, subsidence history and the distribution of plastic zone.The research results are applicated in actual construction and played a good action; then aimed at the space overhead crossing between the platform tunnel and station hall in Xiaobei station ,the excavation sequence is focused, numerical simulation is used to decide which is better, "upper after lower" or "lower after upper", also the surface settlement and internal stress distribution in lining structure caused by these two sequences are summarized; in the end ,with the use of fluid-solid coupling, the ground water loss in subway construction is studied ,the theory of surface settlement caused by groundwater seepage is analyzed and ejection for water plugging by building curtain is proved. Finally the surface settlement control measures of subway in watery strata are proposed.