Construction method for subway tunnel to enter subsurface excavation interval tunnel door from shaft

Abstract

Provided is a construction method for a subway tunnel to enter a subsurface excavation interval tunnel door from a shaft. According to the construction method, a pre-hanging structure for the arch portion of the tunnel door is designed in the stage of excavation from the shaft to the top elevation position of the tunnel door; when the shaft is excavated to the arch portion of the tunnel door, parts of enclosure piles are broken ahead under effective construction monitoring, and construction of the arch portion of the tunnel door is carried out; the construction of the part which may require reverse breaking of the arch portion of the horsehead of the interval subsurface excavation tunnel is carried out in advance, the conventional construction methods which may involve the high-place operation of a bracket at the bottom of the shaft and the safety hazard caused by manually upwardly breaking enclosing piles can be effectively avoided, the operation difficulty and construction risks of similar engineering processes are lowered, the processing requirements of the bad formation during the operation are avoided, and meanwhile the construction period can be shortened to a certain extent.

Description

[0001] 【Technical field】 [0002] The invention relates to the field of urban rail transit underground engineering construction, in particular to a construction method for a subway tunnel to enter a tunnel door in an underground excavation section from a vertical shaft in the form of "surrounding piles + box-shaped main structure". [0003] 【Background technique】 [0004] It is known that, for subway engineering tunnel construction, the current construction method of entering the interval tunnel portal from the shaft is usually to excavate the shaft first to see the bottom, and to make the shaft box-shaped main structure. After the structure reaches the design strength, the surrounding protection piles are removed. Then excavate by climbing, enter the hole in the form of secondary anti-breaking enclosure piles, or directly excavate upwards, and erect the main line steel grid in the section to enter the hole. The main problems of this construction method are as follows: 1: The e...

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Problems solved by technology

The main problems of this construction method are as follows: 1: The elevation of the top of the portal of the main structure is the same as that of the inner contour of the main line structure, and the initial support structure is generally 0.6m~0.8m higher than the portal. The protective piles on the upper part of the door need to be removed upwards. The space for removing the protective piles on this part is narrow, and mechanical equipment cannot be used. Manual removal must be used. However, when the protective piles are removed manually upwards, the work efficiency is extremely low, and there are great potential safety hazards. The operation is difficult; 2. The vibration is large when breaking the concrete. When encountering unfavorable geology such as sand and pebbles, due to its poor self-stabilization ability, landslides may be induced. During the operation in the above-mentioned limited space, the safety of operators is not easy to guarantee; 3. In the vertical shaft enclosure structure of the enclosure piles, the construction of the advanced small conduit is difficult, and the construction effect cannot be guaranteed. It can only be reinforced through the advanced tube shed. If the soil within the Matoumen area needs to be effectively reinforced, it is necessary to excavate in the vertical shaft In the past, reinforcement was carried out in advance by means of rotary spraying or sleeve valve pipe grouting from the surface, which had a great impact on the construction period and cost, and in adverse geological conditions, the reinforcement was difficult and the reinforcement effect could not be guaranteed

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