Large cross-section tunnel supporting system construction method applicable to steep dip layered rock mass

Abstract

The invention relates to the field of highway tunnel and railway tunnel surrounding rock supporting, in particular to a large cross-section tunnel supporting system construction method applicable to steep dip layered rock mass. The method is characterized in that when a forward inclination layer pilot tunnel and an upper part middle pilot tunnel are dug, a temporary support and first and second layer linings positioned in the positions of the forward inclination layer pilot tunnel and the upper part middle pilot tunnel are made; and when a backward inclination layer pilot tunnel and a lower part pilot tunnel are dug, a temporary support and a first layer lining positioned at the backward inclination layer pilot tunnel and the lower part pilot tunnel are made. The method has the advantages that by aiming at the steep dip layered rock mass tunnel digging damage features, the strength and the rigidity of top and arch part supporting structures are mainly reinforced; the strength and deformation characteristics of surrounding rock of tunnel top and layer exposure parts can be effectively enhanced; the deformation and the instability of the surrounding rock in the two weak positions are controlled; and the stability of the rock mass in the arch part or layer exposure parts is ensured.

Description

technical field [0001] The invention relates to the field of surrounding rock support for road tunnels and railway tunnels, in particular to a construction method for a large-section tunnel support system suitable for steeply inclined layered rock masses. Background technique [0002] Rock mass structures are usually divided into five categories: intact structure, block-cracked structure, broken structure, layered structure and loose structure. In engineering, layered rock mass is often seen with the layer as the control structural plane. This type of rock mass can be divided into interbeds, interbeds, thin layers and soft layers. The strength of this type of rock mass in tunnel excavation is mainly affected by rock blocks Strength, structural surface strength, spatial relationship control between layers and tunnel excavation sections. Layered rock mass is mostly sedimentary rock, which can be composed of a single rock layer, or it can be composed of rock layers or interlay...

AI Technical Summary

Problems solved by technology

When excavating a large-section tunnel in a steeply inclined rock mass with good layering and weak interlayers, the stability of the surrounding rock is particularly prominent. At this time, the exposed rock along the bedding is broken and slumped. If the support strength and rigidity are not enough or the timing of support is wrong, the exposed rock of the arch will collapse and cause the vault to fall, which is extremely harmful to the construction of large-section tunnels. unfavorable

[0003] At present, the construction of large-section tunnels still mostly adopts the new Austrian method with anchor-sprayed support technology as the core. The initial support layer is composed of anchor rods, steel mesh, shotcrete, etc. The mesh is usually evenly arranged along the arch wall, and the thickness of the shotcrete is generally equal along the arch wall. This conventional tunnel support system has no targeted effect on the steeply inclined surrounding rock, and can only be increased by increasing the support. scale, etc. to improve the support effect, especially for large-section tunnels, many existing design units set too large values ​​for the thickness of the second lining, up to 900mm thick, which not only caused waste of engineering materials and investment, but also failed to focus on solving the problem. The surrounding rock slide at the exposed part of the arch level and the resulting collapse of the vault are prone to engineering accidents

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