A construction method of underground excavation for long-span and column-free underground stations

Abstract

The invention discloses a large-span column-free underground station underground excavation construction method, which relates to the field of underground station underground excavation construction. The method includes: constructing longitudinal enclosure along the outer contour of the arch roof of the underground station, and longitudinally constructing along the arch foot position of the roof Left and right side pilot tunnels; construct vertical enclosures in the side pilot tunnels that have been supported, and set crown beams on the top of the vertical enclosures; construct roof arches and part of side wall structures in the side pilot tunnels, arches Anchorage with the crown beam, set temporary cross braces between the side wall and the side pilot tunnel; carry out pre-grouting reinforcement for the soil below the longitudinal enclosure, excavate the earth under the longitudinal enclosure section by section, and construct the arched roof structure section by section , the arched roof and the arch foot are connected as a whole, and the back of the roof is backfilled with grouting; after the vault structure penetrates and reaches the design strength, the underground layer of soil of the station is excavated, and the initial support of the side pilot tunnel within the permanent structure is removed. Construction of the middle slab and side wall structure of the basement floor; excavation of the remaining soil mass layer by layer and construction of the remaining station structure.

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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