基于应力释放法的隧道施工初期支护时机探讨  

Discussion on the Timing of Initial Support for Tunnel Construction Based on Stress Release Method

作　　者：郑俊 ZHENG Jun(China Railway 11th Bureau Croup Co.Ltd.,Wuhan Hubei 430061,China)

机构地区：[1]中铁十一局集团有限公司,湖北武汉430061

出　　处：《铁道建筑技术》2021年第1期54-58,共5页Railway Construction Technology

基　　金：国家自然科学基金委川藏铁路重大基础科学问题专项项目(41941018)。

摘　　要：通过在隧道洞壁上施加虚拟支撑力,并逐步减小虚拟支撑力实现开挖过程的应力释放。建立某隧道的数值模型,研究隧道开挖边界变形以及围岩塑性区随应力释放率变化的规律,并根据变形以及塑性区变化规律确定基于应力释放率的最佳初期支护时机。研究结果表明:由于通过在隧道开挖边界节点上施加支撑反力并逐步减小应力释放率,该方法可模拟任意断面隧道的施工;随着应力释放率增加,隧道开挖边界位移以及围岩塑性区深度逐渐变大,变化曲线分为3个阶段;根据隧道开挖边界位移以及塑性区深度变化规律确定初期支护时机范围为应力释放率达到40%~80%,最后综合初期支护的变形以及塑性区确定最佳初期支护时机为应力释放率达到60%。By exerting virtual supporting force on the tunnel wall and gradually reducing the virtual supporting force,the stress relief during the excavation process can be realized.The paper establishes a numerical model of a tunnel,studies the law of tunnel excavation boundary deformation and surrounding rock plastic zone change with stress release rate,and determines the best initial support timing based on stress release rate according to the deformation and plastic zone change rule.The results of the study indicate that this method can simulate the construction of tunnels with arbitrary cross sections due to the application of supporting reaction forces on the boundary nodes of the tunnel excavation and gradually reducing the stress release rate.As the stress release rate increases,the tunnel excavation boundary displacement and the surrounding rock plastic zone depth gradually increase,and the change curve is divided into three stages.According to the tunnel excavation boundary displacement and the depth change law of the plastic zone,the initial support timing range is determined as the stress release rate reaching 40%~80%.Finally,the deformation and plastic zone of the initial support are integrated to determine the optimal initial support timing as the stress release rate of 60%.

关 键 词：应力释放率 非圆形隧道 应力释放法 数值分析支 护时机 

分 类 号：U455.7[建筑科学—桥梁与隧道工程]