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潜水和承压水是地铁软土区间盾构隧道施工过程中的主要危险源,为研究潜水水位变化和承压水水压变化对区间隧道施工的影响,采用FLAC3D软件,选用修正剑桥模型,对不同潜水水位和承压水头作用下盾构隧道的地表沉降、衬砌内力等进行分析。研究结果表明,当隧道洞身全部位于地下水中时:(1)潜水条件下,考虑渗流时地表最大沉降量比不考虑渗流时增大约50%;盾构隧道最大地表沉降与潜水水位呈线性关系;(2)承压水条件下,考虑渗流时地表最大沉降量比不考虑渗流时增大约10%,盾构隧道最大地表沉降与承压水头不成线性关系,随着承压水头的增大,地表最大沉降的增长速率越来越大;(3)潜水水位从-6.8 m变化到-2.8 m及承压水头从8 m变化到12 m的过程中,隧道衬砌管片弯矩和轴力随着潜水水位的升高或承压水头的增大而逐渐减小。
Submersible and confined water are the main hazards in the construction of shield tunnel in soft soil section. In order to study the influence of submerged water level and the pressure variation of confined water on the tunnel construction, FLAC3D software is used to select modified Cambridge model, The ground subsidence and lining internal force of shield tunnel under different submersible water level and pressure head are analyzed. The results show that when the tunnel’s tunnel body is all located in the groundwater: (1) Under the condition of submersion, the maximum settlement of the earth surface when considering seepage is increased by about 50% than that without considering the seepage. The maximum surface settlement of the tunnel is linear with the submerged water level ; (2) under confined water conditions, the maximum settlement of the earth surface when considering seepage is increased by about 10% compared with that without seepage. The maximum surface settlement of shield tunnel is not linear with the pressure head. With the increase of confined water head, (3) In the process of changing the diving water level from -6.8 m to -2.8 m and the pressure head changing from 8 m to 12 m, the bending moment and axial force of the tunnel lining pipe The diving water level increases or the pressure head increases and decreases gradually.