浅埋偏压隧道施工方案优化及受力变形特性分析

Analysis of Excavation Scheme Optimization and Stress-deformation Characteristics of Tunnel Under Unsymmetrical Pressure

结合永吉高速毛坪隧道浅埋偏压段下穿高压线塔工程实例,提出环形开挖预留核心土加钢管桩施工工法。借助于FLAC3D有限差分软件对开挖方案进行施工过程模拟,分析隧道关键位置的受力与变形特性,并与传统环形开挖预留核心土法和CRD法进行对比,取得合理施工工法。然后针对偏压特性,对深浅埋侧的开挖顺序进行了对比。结果表明:(1)CRD法在施工前期效果较好,但整体效果不如环形开挖预留核心土法;(2)施加钢管桩对控制围岩变形,减小围岩应力方面效果突出;(3)先施工浅埋侧比先施工深埋侧相对偏于安全;(4)深埋侧整体应力值明显大于浅埋侧的,隧道存在整体侧移的趋势。

Considering the Maoping tunnel under unsymmetrical pressure on the Yongshun-Jwashou expressway with electricity pylons presented on the ground surface,a construction method named ring excavation reserved core soil with steel pipe pile was proposed. The finite difference method was used to simulate the construction course. The stress and deformation characteristics of tunnel was obtained,and compared with results obtained from ring excavation reserved core soil method and the CRD method. The process of excavating shallow part firstly and excavating deep part firstly were compared for the tunnel under unsymmetrical pressure. The results show that:(1)The CRD method is better in pre-construction,while the ring excavation reserved core soil method is better than the CRD method at overall effects.(2)Application of steel pipe pile has outstanding effect to control the deformation and reduced the stress of the tunnel.(3)Excavating shallow part firstly is more safety than excavating deep part firstly.(4)The stress of deep part is larger than that of shallow part.