扁平特大断面公路隧道核心土模拟与分析

破碎围岩段大断面隧道施工时,较多采用双侧壁导坑法,预留核心土对在开挖过程中隧道的围岩变形和支护受力有很大影响,对隧道围岩稳定性起着至关重要的作用.文章依托广州龙头山单向4车道公路隧道,对扁平特大断面公路隧道在破碎围岩段采用双侧壁导坑法开挖时,预留核心土厚度的区别和开挖方式的不同进行了有限元模拟,分析了围岩应力、围岩塑性区、拱顶沉降、二衬和核心土临时支护的内力,得出了核心土的合理厚度及较为合理的开挖方式.结论对扁平大跨隧道的设计和施工具有指导意义.

Simulation and Analysis of Core Rock in Flat and Large Span Highway Tunnel

The method of double-sides-wall drift is usually adopted when large section highway tunnel is excavated in weak surrounding rock,and the core rock is aquite important factor to the displacement,stability of the surrounding rock mass and the internal force of supporting during excavation.Based on Longtoushan tunnel excavated in Guangzhou,FEM is used to simulate flat and large span tunnel with method for the of double-sides-wall drift under different thickness and construction method for the core rock.The stress,plastic zone and vault displacement of the surrounding rock mass,the stress of lining and temporary supporting are analyzed.The rational thickness and construction method of core rock in flat and large span tunnel are obtained.