Study On Soil Disturbance Caused By Large Diameter Slurry Shield Tunnelling

In recent years, there are many tunnel projects that cross sea or river home and abroad. As the excusive tool for tunnel construction, shield is wildly used in the city subway tunnel construction for its advantages on fast construction speed, little environmental inference and so on. In order to fulfill the traffic demand, the tunnel across sea or river has bigger section. Therefore, the shield method of balance between slurry and water has a wild usage recent years for its series merits on high construction quality, high efficiency, advanced technology, safe and reliable and so on.These tunnels have common features on large diameters, shallow overlaying soil. During the progress of tunnel excavation, the shield will inevitably have disturbance on strata and break the formal balanced state which results to displacement and deformation of the surround strata and earth surface. Recently, there have been many research on this aspect, but the research exclusively focus on slurry-water shield is rare, not to mention large diameter type.This dissertation is based on Nanjing Changjiang slurry tunnel project, through analyzing on theory, filed test, mainly research on disturbance mechanism, disturbance discipline, inference scope and degree of the surround strata during the progress of excavation with large diameter slurry shield, and finally gets results below:1. Measurement on surface settlement, soil horizontal displacement, soil pressure and pore water pressure; analysis based on above mentioned different angles about disturbance mechanism, disturbance discipline, inference scope and degree during the progress of excavation with large diameter slurry shield.2. According to the change of soil stress state, the dissertation brings up a mathematic relationship between stress disturbing degree and distance, and then use this finally get the stress disturbing distance caused by shield propulsion is about one time of the tunnel's diameter.3. According to the initial numerical of later earth pressure , obtained Lateral earth pressure coefficient of silty clay is 0.46.