厦门海底隧道顶板厚度选择及其开挖稳定性分析

在厦门海底隧道轴线的地质剖面图上,选取了4个典型的剖面,应用多裂隙岩体三维弹塑性本构关系和损伤演化方程进行数值分析研究,得到了应力分布、洞周位移、塑性区、损伤区等结果。通过对应力扰动区的分析,以及隧道轴线位置、轴线升高或降低后各剖面应力扰动范围与弱风化层厚度的对比,很容易确定厦门海底隧道的最小顶板厚度;根据应力分布、洞周位移、塑性区、损伤区结果,评价了海底隧道的开挖稳定性。二者的有机结合,说明了将设计方案的轴线位置提高4m后隧道是稳定的。

Research on choosing minimal rock cover and analysing stability of Xiamen subsea tunnel

In order to choose rock cover of Xiamen subsea tunnel now,3D elastoplastic constitutive relation and damage evolution equation for 4 profiles has been done along the longitudinal of the tunnel.The numerical results of stress distribution,displacements,plastic zones and damage zones of rock mass after excavation are got.By means of analysis of stress disturbed area,and comparing rock cover of weak regolith with stress disturbed area at axis and raising or decreasing,it is easy to determine minimal rock cover;similarly,it is satisfying to evaluate stability from the numerical results of stress distribution,displacements,plastic zones and damage zones of rock mass after excavation.Thus,it can be concluded that the tunnel is stable even the rock cover of the subsea tunnel decrease 4m compare to the original design elevation by organic integration of the two.