Construction method for water-rich sand layer shield to pass through steel tube soil nail area

Abstract

The invention discloses a construction method for a water-rich sand layer shield to pass through a steel tube soil nail area. According to the method, a steel tube soil nail is cut and twisted off with the adoption of a high-power rotary digging drilling-jumping hole, the cutting-off sole pressing steel tube is directly pressed into a space below 500 mm of the bottom of a tunnel, the length of theretained steel tube left in the tunnel is not greater than 500 mm, the discharge requirement of the shield is met, the drilling engineering quantity of a transverse barrier clearing hole is reduced to the greatest extent, a drilling hole is backfilled by mortar, excavation parameters of the shield are controlled, and the shield excavates through the steel tube soil nail area; and the method is easy to operate, abrasion of a cutter head and a cutting tool due to the fact that the shield directly passes through the steel tube area is reduced, and the situation that major accidents of surface collapse, building damage and the like happen due to the fact that direct excavation of the shield results in winding of the steel tube soil nail on the cutter head of the shield and causes disturbanceof a soil body is avoided. The problem that a shield tunneling machine is difficulty in construction and high in construction cost when passing through a barrier area.

Description

technical field [0001] The invention relates to the technical field of urban rail transit construction, in particular to a construction method for a water-rich sand layer shield tunneling through a steel pipe soil nailing area. Background technique [0002] The construction operation of the soil nail wall support structure is simple and convenient, and the construction cost is low. It is widely used in the deep foundation pit enclosure structure. Subsequent engineering construction brought a series of troubles. When the Harbin Metro Line 2 shield machine passed through the 360 ​​Building in Jingwei Street, the line encountered a large number of steel pipes with a diameter of φ75mm and a wall thickness of 5.5mm in the range of 130m from the 440th ring to the 549th ring. The length of the nails ranges from 15 to 18m. There are threaded steel anchors with a welding length of 500mm and a diameter of φ22 on the steel pipe wall. There are two layers of 76 steel pipe soil nails int...

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Problems solved by technology

[0006] In the prior art, there is an essential difference in material between the steel strands used in the anchor cables and the steel pipes used in the soil nails. The steel strands have high strength but flexibility, and the steel pipes have high strength and strong rigidity. The stranded wire can be wound on the drill bit of the rotary drilling rig and the cutterhead cutter, but the steel pipe cannot be wound on the drill bit of the rotary drilling rig and t

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