Method of drilling holes in sand-gravel stratum in small space in subway underground excavation station holes

Abstract

The invention discloses a method of drilling holes in sand-gravel stratum in small space in subway underground excavation station holes. The method comprises following steps: S1. starting a sandstonepump to carry out reverse circulation drilling rig drilling; S2. spacing hole drilling: after the reverse circulation drilling rig drilling, drilling successively by means of the reverse circulation drilling rig drilling; S3. after drilling is completed, placing steel reinforcement cages in holes and pouring concrete in conduits. The present invention has the following beneficial effects: a rapidpile-forming method in sand-gravel stratum is provided, which can further reduce the labor force, reduce the frequency of soil disturbance, reduce the effect of group holes and control the settlementof the ground surface, and is also economical compared with the prior art.

Description

technical field [0001] The invention relates to the technical field of bored cast-in-place piles, in particular to a method for drilling holes in a sandy pebble stratum under a narrow space in a tunnel of a subway underground excavation station. Background technique [0002] At present, most of the multi-arch stations constructed by the "PBA" construction method in major cities in China adopt the double-layer pilot tunnel strip foundation method, and only the Olympic Park Station of Beijing Metro Line 15 under construction adopts the single-layer pilot tunnel long pile method. The stratum of Olympic Park Station is basically in fine-grained stratum, and large-diameter bored piles are easier to construct. There is no first case of large-diameter bored piles in large-diameter sand and pebble strata in China. [0003] The construction method of side piles with a diameter of 1m in the cave is relatively mature, but they are all conventional methods. The conventional method of pl...

AI Technical Summary

Problems solved by technology

[0002] At present, most of the multi-arch stations constructed by the "PBA" construction method in major cities in China adopt the double-layer pilot tunnel strip foundation method, and only the Olympic Park Station of Beijing Metro Line 15 under construction adopts the single-layer pilot tunnel long pile method. The stratum of the Olympic Park Station is basically in the fine-grained stratum, and the large-diameter bored piles are easier to construct. There is no first case of large-diameter bored piles in the large-grained sand and pebble stratum in China.

[0003] The construction method of side piles with a diameter of 1m in the cave is relatively mature, but they are all conventional methods. The cofferdams in the cave are placed in mud circulation systems such as mud pools, sedimentation tanks, and slag storage pools in conventional methods, resulting in low efficiency and muddy and messy working conditions on site.

Due to the limited space in the underground cave, potential safety hazards are prone to occur, and continuous construction operations cannot be carried out. Especially for the construction of 1.8m large-diameter pile foundations, the problem of large-volume slag storage in the cave is basically unable to meet the problem, resulting in reduced efficiency and even quality safety. ACCIDENT

[0004] Since most of the stratum is a pebble layer, and the diameter of the pebbles is relatively large, the chassis of the ordinary tire type drilling rig is unstable during the drilling process, and the swing is unstable during the drilling process, which affects the quality of the pile.

[0005] The piles in the cave are located in the sandy pebble formation, and the modified reverse circulation drilling rig has strong suction, and the construction interference of adjacent piles is large, and the hole is easy to collapse

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