Shield machine, the full name of the shield tunnel boring machine. Special project is a tunnel boring machinery, modern shield tunneling machine set of optical, mechanical, electrical, fluid, sensing, information technology one has cutting soil excavation, transportation of soil ballast assembly Tunnel Lining, measurement-oriented correction and other functions, involving multi-disciplines of geology, civil, mechanical, mechanical, hydraulic, electrical, control, measurement techniques, but also to design and manufacture of "tailored" according to the different geological and reliability requirements. The shield tunneling machine has been widely used in the subway, railway, highway, municipal, hydropower tunnel project.
Shield machine tunnel construction with a high degree of automation, save manpower, construction speed, and one into the hole, not climate, land subsidence in the excavation can be controlled to reduce the impact of buildings on the ground and underwater excavation does not affect the water transport characteristics, TUNNEL line is longer, the depth of the larger, more economical and reasonable shield machine construction. The basic working principle of the
shield machine is a cylinder of steel components along the tunnel axis edge forward edge of excavation of the soil. The components of the shell of the cylinder as a shield, its excavation has not been lining tunnel segment plays the role of the temporary support to withstand the pressure of the surrounding soil, and sometimes also to withstand groundwater pressure and groundwater will be blocked out. Excavation, soil, lining, operating under the cover of the shield.
It is understood that the shield construction of the Beijing subway construction tunneling accounts for total 45% of the current total of 17 tunnel boring machines for the effectiveness of the subway construction. The high cost of shield machine, the metro effect but can be increased by 8-10 times, and not on the ground in the construction process, the demolition of a large area, not blocking traffic, construction noise, ground subsidence, does not affect residents normal life. However, large shield machine with high technological added value, the complexity of the manufacturing process, only Europe and Japan, several companies to develop and produce. The
shield machine according to the principle of work is generally divided into hand-dug Shield, squeeze Shield, the cyborg Shield (partial pressure, global pressure), mechanical shield (thoracotomy cutting shield, pressure Shield, Slurry shield, earth pressure balance shield, hybrid shield, shaped shield).
Mud shield machine is pressurized mud or mud (usually bentonite suspension) to stabilize the excavation face cutter behind a sealed bulkhead and mud room between the excavation face, filled with mud, excavation of soil material and mud mixed transportation by the mud pump to the outside of separation plant, slurry separation after repeated use. Earth pressure balance shield machine excavation of the rotation of earth material (if necessary, add foam on soil improvement) as the media of the stability of the excavation face, the knife after-hours closure between the excavation face to form a mud room, cutter increase in soil materials, and then lost by spiral feeder rotate the soil material shipped, soil laboratory soil pressure to adjust the speed of rotation excavation by cutter and spiral output feeder unearthed (rotational speed).
Shield excavation method according to the classification of the shield machine can be divided into: open type, mechanical cutting style, grid-like, and extrusion. Order to reduce the shield construction disturbance on the formation with the jack drive shield so that the incision penetration layer, and then the incision within the soil excavation and transport.
Open excavation
hand digging and semi-mechanical shield are half open excavation, this method is suitable to geological conditions, the excavation face in Tunneling remained stable or supplementary measures to maintain stability, and its excavation from the top layer to dig down. If the soil is poor, but also to borrow the jack plus the support plate on the temporary support of excavation face. Open excavation, treatment of isolated obstacles, correcting, and overbreak are otherwise easily. In order to minimize disturbance of the strata should be appropriate to control the amount of over-excavation and exposure time.
(B) mechanical-cutting excavation
refers to shield diameter is similar to full-face rotary cutter disk excavation. The quality of the geological conditions, the sword plate can be divided into the turret between the seal plate and seal plate two kinds. Turret between the seal plate for better conditions in soil. Broadsword disk excavation, bend construction or correction is not as good as open excavation easy to over-excavation. In addition, the removal of obstructions is not as open excavation. Shield to use the sword plate, the mechanical structure is complicated, consumption gained significant momentum. At home and abroad advanced mud pressure shield, earth pressure balance shield using this excavation.
C grid-like excavation
grid-type excavation, excavation of the surface by a grid beam and the grating is divided into many grid. Supporting role of the excavation surface is produced by the soil cohesion and resistance in the grid thickness within. When the shield driving, the soil is squeezed out from the cell house. According to the nature of the soil, to adjust the opening area of the grid. Grid excavation, all jacks retracted, it will produce a large shield-back phenomenon, leading to surface subsidence in the construction be sure to take effective measures to prevent the shield back.
(D) squeeze the excavation
full extrusion and partial extrusion excavation unearthed or only partially unearthed, strata larger disturbances in the construction of the axis, should be avoided. ground-level structures. Partial extrusion construction, carefully controlled unearthed amount, to reduce and control the surface deformation. The whole extrusion construction, within a certain range of four weeks shield to squeeze dense soil.
Shield machine come out has been nearly 180 years of history began in the United Kingdom, was developed in Japan, Germany world pie network information . The past 30 years, the earth pressure balance in the mud shield machine technology, such as the shield machine, an effective seal to ensure the stability of the excavation surface, control surface uplift and subsidence within the specified range, the use of the tool life as well as in sealed condition, the tool replacement, exploration and research to solve the adverse geological water pressure conditions such as high processing technology, so that the shield machine has been developed rapidly World Steel Pipe News . Shield machine, especially the earth pressure balance and mud shield machine in Japan has developed rapidly due to rapid economic development and the needs of practical engineering. German shield machine technology is unique, especially in the underground construction process to ensure that sealed the premise of up to 0.3MPa pressure to replace the cutter on the tool, thereby enhancing a shield machine tunneling length. Germany has also developed in a sealed condition from the inside of atmospheric space within the large-diameter cutter to replace the worn tool.
Shield machine selection principle is adapted to local conditions, to maximize the degree of mechanization, to reduce the impact on the environment. Shield machine
participate in the Shenyang Subway called the pioneers of number, the total length of 64.7 meters, the shield part of the 9.08 m and weighs 420 tons, its error does not exceed a few millimeters. Shield machine
price: Germany imported about 50 million yuan, the shield machine of the Japan imports about 30 million yuan, made shield machine prices are generally around 25 million.
With independent intellectual property rights in the domestic shield machine is developed by the Shanghai Tunnel Engineering Co., Ltd. China-made "863" series of shield machine. In July 2007, the former shareholders of Northern Heavy Industries Group chairman Geng Hongchen France NFM formally signed a share transfer agreement, the absolute control of the way the successful conclusion of the merger talks which lasted two years, Northern Heavy Industries has the world's most advanced The core technology of the full range of tunneling shield machine and brand.