The Research Of Surface Subsidence Caused By Metro Shield Construction Based On FLAC3D

With the rapid development of economy in our country, the pace of constructionof each big city is gradually accelerated, to solve the urban traffic pressure, the subwayconstruction is in full swing. Shield method is the main method for subwayconstruction, in construction process it will inevitably produces the surface subsidencewhich can endanger the safety of the building, causing economic losses when thesubsidence is too large. So it is necessary to study the characteristics and laws ofsurface subsidence caused by metro shield construction.According to ningbo metro line1shi-hai between specific engineering geologicaland hydrogeological conditions, theoretical analysis the surface subsidence caused byshield construction. Build3D model by FLAC3D finite difference software, numericalanalysis, the cause of surface deformation are discussed, combining with the measuredresults and analysis of its deformation law. The conclusions are as follows:1. With the advance of shield, the displacement of soil above the tunnel axisincreases gradually, the ground settlement was gradually increased, reached themaximum at the top of tunnel displacement; Soil tunnel axis below has obvious uplift,uplift capacity first increased and then decreased gradually, tends to be stable.2. Surface transverse settlement trough width with Shield Advancing and widened,its change range is different. Shielding to6m, settling tank has been deepened andwidened, continue to advance to18m and30m, settlement trough width also increased,but the increase amplitude is smaller, the settlement trough width change rate issmaller.3. With the advance of shield, ground settlement in gradually increases, when theshield to12m, ground surface settlement curve gradually become slow, sedimentationrate has been significantly reduced.4. The results of numerical simulation and actual measurement are basically thesame. It means that numerical simulation method can accurately predict the affectionof surface subsidence and has the certain reference value to the actual engineering.