A construction method for close-distance superimposed shield sections of open-cut tunnels in urban areas with developed spring veins

Abstract

The invention relates to the technical field of open excavation tunnel construction, and discloses a spring line developed urban area open excavation tunnel short-distance overlapped shield interval construction method. Foundation pit earthwork excavation sectioned pouring is combined with main body structure sectioned pouring, and a construction joint is kept away from a shield overlapped area and is arranged at the minimum stress place; during open excavation tunnel construction of the upper portion of the shield overlapped area, after the bottom of a foundation pit is excavated, floor construction is conducted in time, a trolley is moved to a floor (to increase load), after the trolley is moved into place, pouring construction of the open excavation tunnel main body structure is conducted through the trolley, and meanwhile, a shield synchronously penetrates through the open excavation tunnel being constructed from the lower portion of the open excavation tunnel. According to the method, on the premise that grouting is not conducted between the shield and the overlapped tunnel to reinforce soil mass, the load of soil mass above the shield is prevented from decreasing too much, duct pieces move upwards, safe penetration of the shield is guaranteed, meanwhile, the effect of tunnel construction on surrounding ecological environment is reduced to the maximized extent, and the efficiency of open excavation tunnel construction is improved.

Description

technical field [0001] The invention relates to the technical field of open-cut tunnel construction, in particular to a construction method for short-distance superimposed shield sections of open-cut tunnels in urban areas with developed spring veins. Background technique [0002] Subway lines in urban areas are affected by factors such as planning conditions, existing buildings, and station setting forms. It is inevitable that there will be construction of overspan subway lines. In the construction of subways in some cities, in order to ensure the safety of shield tunneling, the traditional construction method needs to carry out large-scale grouting between the shield tunnel and the stacked tunnel in advance to harden the soil, such as the construction method of the stacked shield tunnel (201310174998.2) proposed a construction method for a stacked shield tunnel. In the construction steps, it was proposed that the downlink tunnel should be injected into the sandwiched soil ...

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Problems solved by technology

[0002] Subway lines in urban areas are subject to factors such as planning conditions, existing buildings, and station setting forms. It is inevitable that there will be construction of overspan subways. In the construction of subways in some cities, in order to ensure the safety of shield tunneling, the traditional construction method needs to carry out large-scale grouting between the shield tunnel and the stacked tunnel in advance to harden the soil, such as the construction method of the stacked shield tunnel (201310174998.2) proposed a construction method for a stacked shield tunnel. In the construction steps, it was proposed that the downlink tunnel should be injected into the sandwiched soil between the uplink tunnel and the downlink tunnel through the grouting pipe in the secondary grouting hole. grout; in the secondary grouting hole of the upward tunnel, grout the soil between the upward tunnel and the downward tunnel through the grouting pipe, which can ensure the safe construction of the stacked shield tunnel; but in the spring vein development area Under such special geological conditions, the grouting reinforcement construction will pollute the surrounding springs, and at the same time cause permanent blockage of the springs, seriously affecting the ecological environment; Under the premise of soil reinforcement by grouting between the tunnels, how to ensure the safety of the existing shield section and ensure the smooth construction of the upper short-distance open-cut tunnel, so as to prevent the soil load above the shield from being too large, causing the segments to float up, and at the same time not The impact on the surrounding ecological environment is a difficult problem for project builders

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