Tunnel passing through active fault and calculation method for length of fortification extension section of tunnel passing through the active fault

Abstract

The invention provides a tunnel passing through an active fault and a calculation method for the length of a fortification extension section of the tunnel passing through the active fault. The tunnel passing through the active fault comprises a railway line before fault dislocation, a line needing to be adjusted after fault dislocation and a railway line after fault dislocation which are connected in sequence. The line needing to be adjusted after fault dislocation is located in an active fault passing-through area; the active fault passing-through area comprises a fault fracture zone and two fortification extension sections; the length L2 of the fortification extension sections is calculated according to a formula I: L2 is greater than or equal to (L-L1) / 2; in the formula I, L is the length of the active fault passing-through area, and L1 is the width of the fault fracture zone; the length L of the active fault passing-through area is calculated according to a formula II: D / L + R = Rt; and in the formula 2, D is the fault dislocation amount, R is the gradient of the railway line before fault dislocation, and Rt is the gradient of the line needing to be adjusted after fault dislocation. After fault dislocation occurs in the tunnel, sequential connection is achieved by adjusting the gradient of a railway tunnel line, and the requirement that a train passes at the first time is met.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to a calculation method for the length of a tunnel crossing an active fault and its fortification extension. Background technique [0002] With the vigorous development of my country's railway engineering construction in the southwest region, coupled with the complex and changeable geological conditions in the southwest mountainous area, mountain tunnels crossing faults, especially active faults are becoming more and more common. This kind of dislocation deformation will lead to the destruction of the main structure of the tunnel, and directly cause the tunnel lining concrete to collapse, crack and groundwater seepage, seriously affecting the safety of railway operation. [0003] A large number of studies have shown that near the contact surface between the surrounding rock of the tunnel and the fault, damages such as seams and cracks often occur due to earthquakes, which...

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Problems solved by technology

[0004] However, relying on engineering research data analogy and numerical simulation to determine the length of the extension section of fault fortification cannot be effectively combined with the actual seismic fortification objectives of the project. When the width of the fault fracture zone is small, the numerical simulation method has certain limitations

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