Analysis And Control Of EPB Shield In Water Rich Sand Layer Soil Pressure Balance

Shield machine is a kind of tunnel excavation of special engineering machinery, nowadays, the shield tunneling machine set machine, electricity, liquid, sensor, information technology in one, has the function of cutting soil excavation, transportation muck, assembling of tunnel lining, measuring orientation correction. Shield tunneling machine has been widely used in subway, railway, highway, municipal, hydropower tunnel project.In the shield tunneling process, due to earth pressure balance shield machine limitations and stratum adaptability limitation, in sand excavation, settlement are difficult to control. According to the general experience, there is a large settlement after shield tunneling and shield tail.. According to the pre construction in tracking and measuring results show that driving in sand layer in the shield, the shield about 20 meters in front of a significant settlement, about 3 ~ 5mm. In the process of boring cutter position settlement is about 4~13mm, the synchronous grouting settlement after convergence, the basic stability of the settlement of shield tail pulled out after 15m. Land subsidence is mainly affected by the engineering geology, hydrogeology, segment lining grouting quality, shield machine attitude control.Combined with engineering example of Nanning city track traffic on the 1st line west min shield section ground subsidence, proceed from the characteristics of shield tunnel construction, synchronous grouting, shield posture and line to, focusing on of earth pressure balance shield construction in the process of land subsidence phenomenon, influencing factors and countermeasures were analysis, provide some suggestions to solve problem of shield in the sand ground subsidence.