Underground excavation construction method for large-span column-free underground station

Abstract

The invention discloses an underground excavation construction method for a large-span column-free underground station, and relates to the field of underground station underground excavation construction. The method comprises the steps that a longitudinal enclosure is constructed along the outer contour of an arched top plate of the underground station, and a left side pilot tunnel and a right side pilot tunnel are longitudinally constructed along the arch foot position of the top plate; a vertical enclosure is constructed in the supported side pilot tunnel, and a top beam is arranged at the top of the vertical enclosure; top plate arch feet and part of side wall structures are constructed in the side pilot tunnels, the arch feet and the top beam are anchored, and temporary cross braces are arranged between the side walls and the side pilot tunnels; advanced pre-grouting reinforcement is conducted on a soil body below the longitudinal enclosure, earthwork below the longitudinal enclosure is excavated section by section in the longitudinal direction, an arch top plate structure is constructed section by section, the arch top plate and arch feet are connected into a whole, and backfill grouting is conducted on the back of the top plate; after the arch crown structure is connected and reaches the design strength, a first underground layer soil body of the station is excavated, a side pilot tunnel primary support within the permanent structure range is broken, and a first underground layer middle plate and a side wall structure are constructed; and the remaining soil body is excavated layer by layer and the remaining station structure is constructed.

Description

technical field [0001] The disclosure of the invention relates to the field of station underground excavation construction, in particular to a method for underground excavation construction of a large-span column-free underground station. Background technique [0002] The problem of municipal transportation in big cities is becoming more and more prominent, and the development of high-speed and large-capacity urban underground railways is an effective way to solve this problem. Due to the large span and vertical load of the underground station, the main structural form of the current underground station is a single-column, double-span or double-column, three-span box structure. Organize and reduce the architectural aesthetics of the inner space of the station, and secondly reduce the actual usable width of the platform, limit the combination of stairs and escalators, and reduce the operating efficiency of the station; with the rapid development of urban subway construction in...

AI Technical Summary

Problems solved by technology

[0005] (1) Repeated excavation will greatly disturb the soil layer, which is not conducive to the stability of the soil layer. The lower excavation will easily disturb and damage the upper soil layer, support and lining, resulting in not only large ground subsidence, but also construction risks. huge;

[0006] (2) Due to the large number of working surfaces, the mutual interference is large, the organization and coordination are difficult, the work efficiency is low, and the construction period is long;

[0007] (3) A large number of additional auxiliary measures such as advanced pipe shed and grouting reinforcement are generally required. There is a secondary force transfer between the primary support and the main structure, and the waste of the primary support is large, and the project cost is high

However, the pilot tunnel and buckle arch of this construction method are still constructed by the partial excavation method, which inherits the characteristics of high risk, difficulty, large settlement, and high cost of the partial excavation method. It has certain requirements for the buried depth of the covering soil. Conditions and surrounding environment are good, it is difficult to apply to the construction of large underground structures in soft soil layers or complex environments

[0009] The traditional underground excavation methods for the above-mentioned underground stations are all based on decomposing the large section into small sections, excavating the small-span structure through partial excavation, and finally closing it into a ring to realize the construction of the large-span structure. Therefore, the traditional underground excavation method has relatively large span restrictions. Due to the cancellation of the center column in the column-free underground station, the covering soil load on the roof doubles. The traditional underground excavation method has a series of reasons such as high construction risk, high construction difficulty, high project cost, and long construction period. As a result, the traditional underground excavation method basically cannot be applied to column-free underground stations in Quaternary soil layers, and it is even difficult to apply to the construction of single-column double-span underground stations

Although the "three-step seven-step excavation method" and "arch-covering method" can realize the underground excavation construction of long-span and column-free underground stations, such construction methods need to make full use of the self-supporting capacity of the surrounding rock, and have strict requirements on the geological conditions of the surrounding rock. High, the covering soil is generally required to be deep, and the curvature of the section is required to be relatively large. Its essence is still the partial excavation method, the construction technology is complicated, the requirements for construction risk control are still high, and the project cost is high. Only in Dalian, Qingdao, Chongqing, etc. Application in a few underground stations in rock formations

[0010] Therefore, if a method for underground excavation construction of a pillarless underground station can be proposed, it can not only solve the technical problems of high geological conditions, high risk, long construction period, and high cost of the traditional underground excavation method for underground stations, but also realize a more open underground station. The beautiful pillar-free space finally promotes the double progress of the underground station in terms of construction technology and use function

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