Large-section U-shaped earth pressure balance shield tunnel construction method based on U-shaped shield tunneling machine

Abstract

The invention discloses a large-section U-shaped earth pressure balance shield tunnel construction method based on a U-shaped shield tunneling machine. The large-section U-shaped earth pressure balance shield tunnel construction method comprises the following steps that 1, an opencut tunnel counter-force structure shield launching device is arranged, and the end is reinforced through a large pipeshed in the tunnel entering direction; 2, a launching base is arranged on a bottom plate structure, three first guide rails are arranged on the launching base to serve as a shield tunneling machine guiding rail, three second guide rails are laid in a tunnel portal pilot tunnel, the first guide rails and the second guide rails are connected and located at the connecting position of the shield tailof the shield tunneling machine and a medium shield, and a shield tail welding groove is formed in the launching base; and 3, an opencut tunnel reinforcing section structure is arranged to provide counterforce for the shield tunneling machine. On the basis of the U-shaped shield tunneling machine, a complete set of technologies, including the opencut tunnel counter-force structure shield launchingtechnology, the shield tunneling parameter control technology, the large-section U-shaped shield segment splicing technology and the muck improvement technology, of large-section U-shaped shield construction is formed.

Description

technical field [0001] The invention relates to the field of tunnel construction, in particular to a construction method for a large-section horseshoe-shaped earth pressure balance shield tunnel based on a horseshoe-shaped shield machine. Background technique [0002] At present, in the construction of large-scale railway tunnels, the mining method is the main method, supplemented by a small amount of TBM and shield method, among which the shield method is mainly used for crossing rivers, straits and urban soft soil strata. When the railway mountain tunnel passes through the sandy and new loess strata, the construction method using the mining method requires auxiliary construction methods and high-rigidity support, which is costly. However, the construction method using the shield method is more convenient, and the structure is mainly a single-layer prefabricated segment. The additional construction support cost has obvious advantages, but it also needs to increase the initi...

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Problems solved by technology

Also, because the horseshoe-shaped section does not have the advantage of circular center symmetry, the inner surface of each segment has the characteristics of variable curvature, heavy weight, large inertia, and offset center of gravity, which makes the fine-tuning workload during segment installation very large, and segments are dislocated and overlapped. There are many problems such as many joint phenomena, and the circumferential compressive force is not easy to transmit when the wedge block is finally assembled.

[0006] (4) In view of the large area of ​​the horseshoe-shaped section, the simultaneous excavation of nine cutterheads, the uneven mixing effect, and the presence of blind spots in the mixing, the improvement of the muck soil has great inhomogeneity, which has a great impact on the direction control of the shield body (attitude)

Because the traditional secondary grouting uses double slurry of water glass and cement slurry, a minimum of 4 people can be equipped for each operation, the process is cumbersome and time-consuming, and often occurs the phenomenon of pipe blockage and shield shell locking

In addition, the large-section horseshoe-shaped shield has a large cross-section, and the segment structure itself has a large weight and grout buoyancy. Improper synchronous grouting grout performance and operation can easily cause hidden dangers such as segment cracking

[0008] (6) During the excavation, 3#, 5#, and 7# cutterheads are in the front, and a blind zone is formed between the 1#, 4#, and 6# rear cutterheads. The slag accumulates in the blind zone, causing the thrust to gradually increase and form between the cutterheads. Blind area, the accumulation of muck in the blind area leads to the gradual increase of thrust in the sandy old loess stratum, resulting in difficulty in excavation, increased resistance between the cutter head and the incision, and the soil column in the blind area is difficult to destroy and directly pushes into the partition in the soil bin, resulting in an increase in thrust At the same time, there is no speed, and the torque of the cutter head increases accordingly

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