Low-channel progressive construction tunnel entrance method of subway mined tunnel

Abstract

The invention relates to a low-channel progressive construction tunnel entrance method of a subway mined tunnel. The method comprises the following steps that: (1), a structural outline of a tunnel under construction is determined according to a using function requirement and progressive portals with the gradually changed heights are manufactured according to construction procedures; (2), expanding excavation is gradually carried out along an effective main track tunnel structural outline at the direction perpendicular to a main track tunnel at the tunnel under construction; and one progress portal is arranged timely when excavation is carried out once until the excavation and support of the part are completed; and (3), in the progress portals, a main track tunnel support portal is constructed along the main track tunnel outline, thereby supporting the progress portals perpendicular to the main track tunnel; and then redundant vertical support rods of the progress portals at the main track tunnel direction are cut and removed. The method has the following beneficial effects: the low-channel progressive tunnel entrance way is used and the tunnel under construction does not need to be elevated and excavated, thereby reducing the vertical height of the tunnel under construction, minimizing the disturbance on the undisturbed formation stratum, and obviously improving safety of the tunnel excavation construction work and the like.

Description

technical field [0001] The invention relates to the technical field of tunnel engineering design and construction, and relates to a low-passage progressive entry method for subway underground excavation tunnels. Background technique [0002] The force of the subway project is complex, the construction risk is high, and the project cost is high, especially the underground excavation construction of the subway tunnel, which is a difficult problem for every subway tunnel project. [0003] The scheme of subway underground excavation tunnel entering the main line tunnel (entry tunnel) from the construction passage, the traditional entry method is (see figure 1 Shown): The section of the construction passage in the heightened part of the tunnel, on one side of the high construction passage, the main line tunnel is excavated in blocks. In the traditional method of underground excavation, due to the heightening of the section of the construction passage, the overall height of the c...

AI Technical Summary

Problems solved by technology

In the traditional method of underground excavation, due to the heightening of the section of the construction passage, the overall height of the cross passage section is increased (about 5 meters higher than the section required by the function), which increases the internal force of the secondary lining structure and causes the construction passage to be buried. The depth becomes shallower, which further increases the disturbance to the original underground rock and soil, and greatly increases the engineering risk. Since the elevated part has no functional requirements at all, it also causes more engineering waste, which has great impact on the subsequent excavation. Both the pouring of the second lining and the pouring of the second lining have left great risks and hidden dangers. It is an old and wrong concept of the tunnel construction method that is on the verge of being eliminated.

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