大跨浅埋偏压隧道围压实测及结构受力分析

Site Measurement of Surrounding Rock Pressure and Analysis of Structure Stress of Large-span Bias-pressured Shallow Tunnels

大跨浅埋偏压隧道由于其非对称的受力条件,易引发结构变形与开裂等突出问题,近年来越来越受工程技术界的重视。以邢汾高速公路邢台段后偏梁大跨度隧道浅埋偏压段为例,通过实测围岩压力,根据荷载结构法的基本原理,利用ANSYS软件对其结构受力特性进行数值分析,得到结论:实测的围岩压力分布和偏压的地形之间具有较为一致的对应性,即围岩压力受地形的影响显著;二衬总应力受轴力引起的应力影响较小,主要受弯矩引起的应力控制,整个拱圈范围内最危险的部位是在受围岩压力最大的左侧拱肩处;随着二衬厚度的变化,二衬总应力在不同的部位均发生相应变化,但变化幅度均不大。相关研究结论为后续类似大跨浅埋偏压隧道的合理设计与施工提供参考依据。

The asymmetrical stress condition of the Large-span bias-pressured shallow tunnels can cause many problems easily,such as structural deformation and cracking. These problems have attracted more and more attentions from engineering and technology research field in recent years. The Houpianliang large-span bias-pressured shallow tunnel in Xingtai section of Xingtai-Fenyang highway was taken as an example to numerically analyze the mechanical characteristics of the structure by adopting ANSYS,according to the data of site measurement of surrounding rock pressure and the principle of load structure method. The results indicate that： the actual measured surrounding rock pressure is consistent with the bias terrain,which means the surrounding rock pressure is influenced by topography significantly; the total stress of the second lining is mainly controlled by the stress from bending moment and is less influenced by the stress from axial force,the weakest part within the scope of the arch ring is the left spandrel which is subject to maximum pressure; with the change of the thickness of the second lining,its total stress changes in different positions accordingly within a small range. These conclusions can provide references for the rational design and construction of similar large-span bias-pressured shallow tunnels.