Joint steel frame supporting system for excavating auxiliary tunnel on main-tunnel arch wall and construction method of joint steel frame supporting system

Abstract

The invention relates to a joint steel frame supporting system for excavating an auxiliary tunnel on a main-tunnel arch wall and a construction method of the joint steel frame supporting system. The auxiliary tunnel of a single-arch large-span type underground-excavated station is required to be connected with the main-tunnel arch wall at a main-tunnel arch wall position. The higher is a cross section of the auxiliary tunnel, the larger is a span. The longer is a free face of a joint arch portion, the larger is excavating risk. Multiple lower straight-wall steel frames are vertically arranged on straight walls on two sides of a joint. The upper ends of the lower straight-wall steel frames are connected through arc-shaped steel frames, the arc-shaped steel frames close to a main tunnel incline to the main tunnel, and the arc-shaped steel frames are connected through perpendicularly-arranged horizontal connecting steel frames. Inclined arch portion arc-shaped steel frames adjacent to the main tunnel are connected with cut-off steel frames of the main tunnel through the perpendicularly-arranged horizontal connecting steel frames to form a firm supporting framework. The arc-shaped steel frames are utilized on a free section of a joint arch portion to realize effective connection between main tunnel steel frames and auxiliary joint steel frames, load of a main tunnel arch portion can be transmitted effectively, settlement of a tunnel vault can be controlled effectively, and construction risk for punching on the arch wall is reduced.

Description

technical field [0001] The invention belongs to the technical field of tunnel engineering, and in particular relates to an interface steel frame support system for opening an auxiliary tunnel with an arch wall in a main tunnel and a construction method thereof. Background technique [0002] In the construction of urban rail transit, with the successful implementation of excavated stations with single-arch and large-span sections in rocky strata in Chongqing, the use of excavated stations with single-arch and large-span sections in rocky strata has also been widely used in various places. The characteristics of the single-arch long-span section lead to the need to form an interface at the arch wall of the auxiliary tunnel, which leads to the formation of the free surface at the arch part of the main body and the auxiliary interface. With the increase of the height and span of the auxiliary tunnel, the air surface The length and construction risks have also doubled; the curre...

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Problems solved by technology

The characteristics of the single-arch long-span section lead to the need to form an interface at the arch wall of the auxiliary tunnel, which leads to the formation of the free surface at the arch part of the main body and the auxiliary interface. With the increase of the height and span of the auxiliary tunnel, the air surface The length and construction risks have also doubled; the current treatment of this interface is too random, causing great troubles to site management—after the steel frame of the main tunnel is cut off, it often cannot be connected in time and effectively, and the arch load cannot be transmitted downwards. It leads to the partial pressure of the arch; during the excavation process, it is often impossible to close the steel frame step by step and form a stable support system-if the surrounding rock is weak and the surrounding rock is relatively broken, it will directly threaten the cavern and surrounding buildings on the surface Safety

[0003] Theoretically, in order to achieve the most effective connection between the truncated steel frame of the main tunnel and the interface steel frame, it is necessary to make a three-dimensional space curved steel frame. However, it is conceivable that the actual processing of such a complex steel frame is very difficult. It is easy to invade the second lining limit of the main tunnel when it is difficult to ensure the construction accuracy, and the steel frame is truncated when it is responsible for the main tunnel. The transmitted axial force and the vertical pressure of the surrounding rock of the vault at the interface are not ideal.

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