THEORETICAL STUDY AND ANALYSIS OF SITE OBSERVATION ON THE INFLUENCE OF SHIELD EXCAVATION ON SOFT CLAYS AROUND TUNNEL
盾构掘进对隧道周围土层扰动的理论与实测分析

The main issue considered both in the design and construction in the urban environments is controlling of the ground movement to keep the safety of building adjacent to tunnel and the various underground municipal facilities. The general analysis on the ground disturbance caused by shield excavation shows that the movement of soil around the shield tunnel presents deferent regional characteristics,and the interfaces of various disturbed zones change with the magnitude of pressure on the working face. As the existing underground drainage pipe itself is of given rigidity,the sheltering will affect soils,and may change their moving characteristics. Based on the tunneling of Shanghai Metro Line No.2 in the ground beneath the drainage pipe,by surveying the pore water pressure,ground movement which includes the soil layer settlements,the horizontal soil displacements in two directions in field,the co-relationship between the ground movement and tunneling is studied. The study shows that,while the shield approaching,crossing and leaving the surveying zone,the ground movements in different zone around the Metro Tunnel present respective characteristics.