超浅埋盾构隧道近距穿越既有建筑物影响数值分析

Numerical Analysis on the Impact of Short Distance Crossing of Existing Buildings by Ultra-shallow Buried Shield Tunnel

本文以杭州某软土地区超浅埋盾构隧道施工为例,基于PLAXIS 3D有限元软件,分析盾构施工过程中建筑物位移、弯矩和周边土体变形规律,并探讨注浆压力对隧道上方土体影响规律和盾构埋深对建筑物变形的影响。结果表明:在隧道上下方向与隧道竖向距离越小,土体沉降越大;既有建筑物一侧土体水平位移及隧道衬砌剪应力大于另一侧。同步注浆对建筑物变形影响明显,当隧道上覆土层厚度小于9 m时,上覆土层越浅,既有建筑物隆起现象越明显;当上覆土层厚度大于9 m时,既有建筑物出现沉降。

Taking the construction of an ultra-shallow buried shield tunnel in a soft soil area of Hangzhou as an example,based on PLAXIS 3 D finite element software,this paper analyzed the deformation laws of building displacement,bending moment and surrounding soil displacement during shield construction.Furthermore,it discussed the influence of grouting pressure on the soil above the tunnel and the influence of shield burial depth on building deformation.The results show that the vertical distance between the upper and lower direction of the tunnel and the tunnel,the greater the soil settlement;the horizontal displacement of soil on one side of the existing building and the shear stress of tunnel lining are greater than that on the other side.Synchronous grouting has an obvious impact on the deformation of buildings.When the thickness of the overlying soil layer of the tunnel is less than 9 m,the shallower the overlying soil layer is,the more obvious the uplift of existing buildings is.When the thickness of the overlying soil layer is greater than 9 m,the settlement of existing buildings occurs.