软化泥岩对隧道仰拱的受力特性影响研究

摘要

With regard to the phenomenon of crack and floor heave of Shangzhuang tunnel on Baoji-Lanzhou Passenger Dedicated Line, surrounding rock pressure,stress of steel arch,strain of shotcrete,axial force of steel and contact pressure between the primary lining and secondary lining obtained by means of in-situ monitoring. Development law over time and spatial distribution along the tunnel ring of the stress and strain were then dis-cussed;The force characteristics of tunnel invert before and after the mustone softing in water was analysed with the use of numberical simulation. It is concluded that the stress of the invert is not symmetric, and the values of stress and strain on left are higher than those on the right,which might lead to the crack of invert. At the same depth, the vertical displacement after mudstone became softened was much higher than that before mudstone be-came softened,and the plastic zone radius also increased obviously.The softening of mudstone due to water is an important factor leading to the floor heave and the crack of tunnel invert. The research methods and conclusions in this paper may provide reference for the analysis of crack and floor heave of similar tunnel invert.%针对宝兰客专上庄隧道仰拱底鼓开裂现象，采用现场监控量测的方法得到隧道围岩压力、钢拱架应力、二次衬砌混凝土应变、钢筋轴力和二衬压力，分别讨论应力和应变随时间演化特性和沿仰拱横断面的空间分布规律；采用数值模拟的方法分析泥岩遇水软化前后隧道仰拱的受力特性。研究结果表明：仰拱基底受力不均匀，左侧应力应变值大于右侧，导致仰拱底板开裂；泥岩遇水软化之后拱底同一深度处竖直位移远大于软化之前位移值，并且拱底泥岩软化之后仰拱下部塑性区范围明显增大，泥岩遇水软化是引起隧道仰拱底鼓开裂的重要因素。研究方法和结论对分析相似隧道仰拱底鼓开裂的原因具有一定参考价值。