A construction method for underground excavation of large-section tunnels in soft rock formations

Abstract

A soft rock stratum underground excavation large-section tunnel construction method comprises the following steps of conducting excavation on the upper portion of the center of an arc part to form an arc part small pilot tunnel, and arranging an arc crown vertical supporting system in the arc part small pilot tunnel; conducting excavation to form a left upper pilot tunnel, a left middle pilot tunnel, a right upper pilot tunnel, a left lower pilot tunnel and a right lower pilot tunnel in sequence, and reserving a core rock wall in each pilot tunnel; pouring inverted arc concrete on the left side and right side and inverted arc backfill; pouring the arc part of a tunnel and a side wall secondary lining; excavating the core rock walls; pouring inverted arc concrete and inverted arc backfill. A supporting system adopted in the construction method comprises the arc part small pilot tunnel, a manual hole digging pile, the arc crown vertical supporting system, a side wall preliminary bracing and a core rock wall bracing, wherein the arc crown vertical supporting system comprises a steel pipe support penetrating through the manual hole digging pile and the arc part small pilot tunnel, and an independent foundation is arranged on the bottom of the steel pipe support and located on the bottom of the manual hole digging pile. According to the soft rock stratum underground excavation large-section tunnel construction method and the supporting system, sedimentation of the arc part of the tunnel can be effectively controlled, excavation footage is large, construction progress is accelerated, arc part secondary lining can be realized early, and construction safety is guaranteed.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to a construction method for underground excavation of large-section tunnels in soft rock formations. Background technique [0002] In recent years, with the rapid development of the transportation industry, remarkable achievements have been made in the construction of railways, highways, and subways. The resulting transportation network has become increasingly dense and its coverage is expanding. Therefore, the development of underground space has been paid more and more attention to by builders, among which tunnel construction technology has always been one of the important topics for builders to explore. In the process of tunnel construction, different construction techniques are adopted due to different rock masses, while traditional large-section tunnels in rock formations are mostly constructed by the double-side-wall pilot pit method. [0003] The construction of...

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Problems solved by technology

[0015] The double-side-wall pilot pit method can better complete the construction task of large sections in rock formations along the road, but this method has many construction procedures, complicated construction organization, small operation area, and only small-scale mechanical operations can be used, and the footage is short and the construction progress is slow. ; It is difficult to control the deformation of the ground and the settlement of the arch, and the construction safety is average; the area of ​​the air is small, and the damage to the middle partition by blasting is difficult to avoid, resulting in potential safety hazards; the control of the blasting vibration speed is difficult; after the second lining of the arch wall is poured, There is no reliable embedding at the bottom of the wall, and the lateral pressure is relatively large. When the inverted arch fails to follow up in time, there is a risk of sliding at the bottom of the wall; there are many temporary supports, and the construction cost is high

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