地铁盾构隧道穿越大直径越江隧道的影响分析

新建盾构隧道近距离穿越既有隧道时,会对既有隧道结构产生影响。针对地铁盾构隧道下穿大直径越江隧道,在充分考虑衬砌的横观各向同性性质、盾构施工开挖面的支撑力、同步注浆压力、扰动层厚度等因素的基础上,应用三维有限元数值方法,研究了新建盾构隧道施工引起既有越江隧道的变形以及内力的变化规律,同时获得了越江隧道的影响范围。研究结果表明,越江隧道的最大沉降及侧移发生在对称面上,并且对侧移的影响较小;越江隧道经历了加载、卸载、再加载的过程;影响范围集中在垂直于越江隧道轴线方向盾构穿越前2D、穿越后2D的范围内。

Analysis on Influence of Subway Shield Tunnel Construction on Overlying Cross-River Tunnel

With the development of underground traffic in cities,there are more and more cases of new tunnel construction nearby existing tunnels and the construction of undercrossing shield tunnel will affect the adjacent overlying tunnel inevitably.In order to know the effect mechanism clearly and thoroughly,some studies were carried out on this matter in this paper.In the studies,the transversely isotropic property of tunnel lining,the cutting face support pressure of shield machine,the grouting pressure,the thickness of the disturbed soil and so on are considered and the influence of subway shield tunnel construction on the large diameter cross-river tunnel is analyzed using the three-dimensional finite element method.Through the studies,the changing laws of settlement,lateral displacement,and internal forces of the cross-river tunnel are obtained,and the influence range of the cross-river tunnel induced by shield tunnel excavation is also gained.The results of simulation show that the peak values of settlement and lateral displacement of the cross-river tunnel appear on its symmetrical plane;the value of lateral displacement is extremely limited;the cross-river tunnel experiences a sequence of processes as loading,unloading,and reloading;and the influence range of the cross-river tunnel is distributed along the axis of the subway tunnel with 2D before crossing the overlying tunnel and 2D after crossing it.The results of this paper will offer valuable references to theoretical analyses and similar engineering constructions.