跨走滑断层隧道结构影响分区及设防范围研究

Study on the Impact Zoning and Fortification Range of Tunnel Structures Crossing Strike-slip Faults

  • 摘要: 针对跨走滑断层隧道结构影响分区及设防范围问题,以某高海拔高烈度区活动断层隧道为背景,采用有限差分数值模拟方法,分析走滑断层错动下隧道结构应变、变形及内力特征,提出走滑错动影响范围及分区,并通过跨走滑断层隧道模型试验,验证错动破坏机理及结构响应特征,得出断层错动对隧道结构的影响规律与范围。研究结果表明,断层走滑错动下隧道以拱腰水平受压变形为主,随错动量增加变形持续增大,但增长幅度降低,影响分区可分为主要影响区、次要影响区和稳定区,主要影响区为固定盘侧1.4D、活动盘侧2.1D区域及断层带全段(D为隧道跨径),活动盘侧次要影响区为2.1D~6.3D区域,其他区域为稳定区。最大剪应力主要集中在错动影响区,需重点加强错动影响区抗错断设计。断层带受活动盘联动错动影响,位移呈逐级递增趋势,上下盘与断层交界面为主要滑动面,断层带内相对错动较小,隧道结构受断层错动影响范围为断层带内部、上盘0.7D、下盘1.5D区域。

     

    Abstract: To address the issue of impact zoning and fortification range for tunnels crossing strike-slip faults, a tunnel in a high-altitude and high-intensity area with active faults was studied. Using finite difference numerical simulation, the strain, deformation, and internal force characteristics of tunnel structures under strike-slip fault dislocation were analyzed. Impact zones and corresponding zoning were proposed, and a physical model test of the tunnel was conducted to validate the fault dislocation failure mechanisms and structural response characteristics. The impact scope and patterns induced by fault dislocation were determined. The results indicate that under strike-slip fault dislocation, the tunnel primarily undergoes horizontal compressive deformation at the arch haunch. As fault dislocation increases, deformation continues to grow, but the rate of growth decreases. The impact zones are divided into three categories: primary impact zone, secondary impact zone, and stable zone. The primary impact zone includes ranges of 1.4D on the fixed fault wall, 2.1D on the active fault wall, and the entire fault zone (where D is the tunnel span). The secondary impact zone on the active fault wall ranges from 2.1D to 6.3D, while other areas fall into the stable zone. Maximum shear stress is concentrated in the fault dislocation-affected zone, which requires enhanced fault dislocation-resisting design. The fault zone exhibits a stepwise decrease in displacement due to the joint displacement of the active wall, with the interface between the upper and lower walls and fault serving as the main sliding surface. Relative dislocation within the fault zone is minimal, and the tunnel structure's affected range includes the fault zone interior, 0.7D on the upper wall, and 1.5D on the lower wall.

     

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