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目前盾构工法广泛应用于城市地铁的建设之中,而隧道开挖面稳定性是影响隧道施工安全性的重要因素。采用数值模拟的方法,对考虑流固耦合影响的深层盾构隧道砂土层开挖面稳定性进行了模拟研究,并利用自己提出的一套新的判别准则来确定盾构隧道开挖面极限支护压力。相比以前的研究,该准则不仅考虑了盾构隧道开挖面直径对确定极限支护压力的影响,而且也考虑了在开挖面位移曲线突变和近线性两种类型下的极限支护压力如何确定。利用该判别准则,对影响渗流状态下砂土层隧道开挖面稳定性的因素——土体饱和渗透系数、渗流持续时间、地下水位埋深和孔隙率等进行了参数敏感性分析。研究结果表明,土体饱和渗透系数、渗流持续时间、地下水位埋深均与开挖面极限支护压力成正比关系;而随孔隙率变化,开挖面极限支护压力则变化不大。
At present, the shield construction method is widely used in the construction of urban subway, and the stability of tunnel excavation surface is an important factor affecting the construction safety of the tunnel. The numerical simulation method was used to simulate the excavation surface stability of deep shield tunnel considering the influence of fluid-structure interaction. A new set of criteria was proposed to determine the limit of shield tunnel excavation face Support pressure. Compared with the previous studies, this guideline not only considers the influence of shield tunneling face diameter on the determination of the ultimate support pressure, but also considers the limit support pressure under both sudden and near-linear displacement of the excavation face How to determine. By using this criterion, the parameter sensitivity analysis of the factors influencing the stability of tunnel excavation face under seepage condition, such as soil saturated permeability coefficient, seepage duration, groundwater depth and porosity, is carried out. The results show that the saturated hydraulic conductivity, the duration of seepage and the buried depth of groundwater are all directly proportional to the ultimate bearing pressure of excavation face. However, with the change of porosity, the pressure of limit support of excavation face little change.