1 Preface
Pipe jacking machine is a kind of non-excavation construction of underground pipeline (outer diameter up to 3.8m) of the special digging machinery and equipment, it is the form of hand-digging, extrusion type development to the semi-mechanical type. Due to the development of urban construction, the environmental protection around the construction of higher requirements, with the accumulation of construction experience, scientific and technological advances and mechanical and electrical manufacturing level, so that the form of pipe jacking machine to the mechanical rotary cutting type, mud and water balance type, soil pressure balance type, as well as can be adapted to the development of soft and hard soil layer of advanced models. Pipe jacking machine cutting cutter drive form of hydraulic drive and motor-driven points. the early 1980s, Japan developed a large cutter motor-driven soil pressure balance pipe jacking machine; China's first large cutter disk of 1440mm motor-driven soil pressure balance pipe jacking machine was successfully developed in Shanghai in 1992, the second is a large cutter disk of 2400mm panel-type motor-driven soil pressure balance pipe jacking machine, its outer diameter of 2900mm; in 1994 to 1994, the first large cutter disk was developed in Shanghai, the second is a large cutter disk of 2400mm panel-type motor-driven soil pressure balance pipe jacking machine, its outer diameter of 2900mm. 2900mm; in 1994-1998, Shanghai has developed and successfully applied several large cutter plate motor-driven soil pressure balance pipe jacking machines, such as 1650mm, 1800mm, 3000mm (OD 3540mm) and 2000mm; thereafter, Zhenjiang, Yangzhou, Hubei and other areas of the relevant manufacturers have also developed large cutter plate motor-driven soil pressure balance pipe jacking machines; Beijing has also put the soil pressure balance pipe jacking machines that can be adapted to the needs of the market; and Beijing has also put the soil pressure balance pipe jacking machines that can be adapted to the needs of the market. Pipe jacking machine; Beijing also can adapt to gravel soil layer pipe jacking machine development and application of technology as the Beijing Municipal Science and Technology Commission's scientific and technological development projects, in 2002, a large cutter disk motor-driven soil pressure balance pipe jacking machine used in Beijing sewage treatment projects in the pipe jacking construction; in late 2002, Guangdong has developed and successfully applied a 3600mm outside diameter of the large cutter disk motor-driven soil pressure balance pipe jacking machine. At present, the large cutter disk motor-driven soil pressure balance pipe jacking machine has become a series in China, the pipe jacking method has also been rated as a national work method, and has been widely used.
2 big cutter disk motor drive soil pressure balance pipe jacking machine
2.1 structure of pipe jacking machine
Large cutter disk motor drive soil pressure balance pipe jacking machine mainly consists of big cutter disk, big cutter disk drive device, front and rear shells, stopping device, connecting the two shells of the corrective cylinder group and hinged sealing device, the soil screw conveyor, the corrective cylinder hydraulic power station and hydraulic piping, lubricating grease pump and grease delivery piping, pumps and grease delivery piping, lubricating grease pump and grease delivery piping, lubricating grease pump and lubricating grease delivery piping, and lubricating grease pump and grease delivery piping. The hydraulic power station and hydraulic pipeline of the correcting cylinder, lubricating grease pump and grease conveying pipeline, mud (water) adding device, electrical cabinet of the driving motor and pipe jacking manipulator, and so on.
2.2 Structural features
2.2.1 The large cutter disk has no panel, which consists of 3-4 spokes or reinforcing rods (circle plate) and axle sleeve, and the front of the width is set up with different cutting heads according to different soil qualities, and several stirring rods are set up at the back of the spokes, which can constantly stir the cutting soil in the sealed soil bin, so that the soil in the bin has very good plasticity, mobility, and water-stopping, and make the soil discharged smoothly; there is a triangle in the center of the cutter disk, which makes the soil flow smoothly, and there is a triangular shape in the center of the cutter disk. Discharge; the center of the cutter disk has a triangular fishtail-shaped cutting knife, and there are grouting holes on the spokes and at the center of the cutter disk;
2.2.2 The large cutter disk adopts the center support without large bearings;
2.2.3 The application of the domestic planetary gear reducer and the clutch power transmission structure, the whole cutter disk drive device drive with high efficiency, low noise, low heat generation, simple installation and maintenance, and reliable work;
2.2.4 Adopting electric motor-driven belt-type screw conveyor without center shaft, whose soil outlet is located at the end face, which can form a longer soil plug, and can also convey stones and gravel of a certain size;
2.2.5 Pipe jacking machine is equipped with a compartment plate in the front casing (with grouting pipe and soil pressure gauge set on it), which divides the front casing into sealing soil compartment and power compartment, and the big cutter drive device is located in the middle of the compartment plate, and the compartment plate is installed in the middle of the compartment plate. The big cutter disk drive device is located in the middle of the bulkhead, and the screw conveyor is installed in the lower part of the bulkhead;
2.2.6 The left side of the rear shell of the pipe jacking machine is equipped with hydraulic power station for correcting cylinder, electrical cabinet and lubricating grease pump, and the right side of the machine is equipped with manipulator;
2.2.7 This kind of pipe jacking machine does not need the second conversion process of hydraulic power equipment when it is constructed out of the hole, and the whole set of equipment is simple in structure, convenient in construction and good in reliability.
2.3 Working Principle of Pipe Jacking Machine
Firstly, the main jacking cylinder in the working well pushes the pipe jacking machine forward, and at the same time, the big knife disk rotates to cut the soil, and the soil under the cutting enters into the sealing soil silo and the screw conveyor, and it is extruded to form the compressed soil with a certain soil pressure; after the rotation of the screw conveyor, it conveys out the soil under the cutting. The value of soil pressure in the sealed soil bin can be controlled by the amount of soil discharged from the screw conveyor or the forward speed of the pipe jacking machine, so that this soil pressure is balanced with the static soil pressure and groundwater pressure in front of the cutting surface, thus ensuring the stability of the excavation surface and preventing the ground from settling or bulging.
Because of the large cutter disk without panels, its opening rate is close to 100%, so the earth pressure value measured by the earth pressure meter located on the bulkhead is approximate to the earth pressure of the cutting surface.
According to the characteristics of different strata of the pipe jacking machine excavation surface, by adding water, clay slurry (or bentonite slurry), various ratios and concentrations of slurry or foaming agent and other additives to the front of the cutter plate and the soil bin, so that hard clay, sandy clay, water-bearing sandy clay and sandy gravel soil that is generally difficult to construct into a plasticity, fluidity and water-stopping soil, not only by the spiral conveyor can be discharged, but also to the soil pressure before excavation. It can not only be discharged smoothly by the screw conveyor, but also hold the soil pressure and groundwater pressure in front of the excavation and keep the soil in front of the cutter plate stable.
If the driving power of the cutter is increased and the cutter body is changed, it can also be used for digging construction in mudstone, strongly weathered and moderately weathered sandstone, and it can also be used in various strata such as the water-bearing sand layer which is easy to be collapsed, and the gravel layer which is mixed with pebbles, etc. This pipe jacking machine is more adaptive to the soil layer.
2.4Technical Parameters of Pipe Jacking Machines
Table 1 lists the technical parameters of Japanese large cutter disk motor-driven soil pressure balance pipe jacking machines, and Table 2 shows the main technical parameters of several typical large cutter disk motor-driven soil pressure balance pipe jacking machines in China.
3 Application of pipe jacking machine
3.1 Shantou City, Guangdong Water Transmission Project
There is a water transmission pipe with length of 58m and external diameter of 1400mm crossing the main road (Jinsha East Road) in Shantou City, Guangdong. A semi-remote-controlled φ1400mm large cutter motor-driven soil-pressure balanced pipe jacking machine (Photo 1) was used for the construction.
The pipe jacking stratum was sandy soil (mainly medium sand, also containing some shells with a diameter of 10-14mm), the groundwater level was below 0.5m on the surface, and the overburden on the top of the pipe was 3.3m thick, and there were more complicated underground pipelines to be protected. The top course of 58m was completed in 13 days, and the ground settlement was 0~10mm.
3.2 Xi'an Drainage Pipe Jacking Project
There is a rainwater interceptor main in Xi'an, of which the pipe of the B bidding section is 512m long, and crosses the group of houses and the city's traffic artery along the way, with the design of the longitudinal slope of 7/10,000 and an average depth of burial of 9m, and the rainwater pipeline is made of reinforced concrete pipe with the specification of φ The rainwater pipe is made of reinforced concrete pipe with specification of φ3000mm, the length of pipe section is 2.5m, and the construction adopts φ3000mm large cutter disk motor-driven soil pressure balance pipe jacking machine, and two relay rooms are set up. As the soil layer of jacking is wet trapped clay, there are oxidized spots and shell fragments in the soil, sand is sandwiched between the layers, with wet trapping, hard-plastic to plastic, and the cohesion value of the soil is as high as 45-55kPa, for this reason, in addition to water injection ports on the front side of cutter plate and screw machine, 8 water injection holes are arranged on the partitions of the soil bin of the jacking machine and the amount of water injection is strictly controlled according to the current value of the cutter plate driving motor during the construction, in order to ensure the bearing capacity of wet subsidence loess. There is no crack in the house during the construction, and the ground traffic is normal. After the measurement after the construction, the elevation of the pipe position and the deviation from the left and right of the whole construction section satisfy the design requirements, and the ground settlement along the line is less than 5mm.
3.3 Shanghai Sewage Treatment Project
φ1650mm (Photo 2), φ1800mm, φ3000mm (Photo 3) and φ2000mm several specifications of the Large cutter motor-driven soil-pressure balance pipe jacking machine, has been used in Shanghai sewage treatment project pipe jacking construction, using a fixed-speed soil discharge, variable-speed jacking soil-pressure balance construction technology, safely through the humble houses, railroads, busy traffic on the road, underground pipelines, rivers and embankments flood control wall and other buildings, to achieve a small ground settlement, good directional control of the effect.
3.4 Guangzhou Liwan Lake Power Tunnel Project
Guangzhou Liwan Lake φ3000mm Power Tunnel Project is more than 400 meters long, using the outer diameter of 3600mm large cutter disk motor-driven soil pressure balance pipe jacking machine (photo 4) for jacking construction, the pipe overburden of 4-6m, in the layer of powdery fine sandy soil, the groundwater table is high. The pipe jacking construction lasted about two months from the beginning of December 2002 to the end of January 2003, safely traversing Huangsha Avenue, underground pipelines, Liwan Lake and the foundation of one building (concrete piles).
3.5 Application in other projects
Large cutter motor-driven soil pressure balance pipe jacking machine is also used in Beijing, Tianjin, Zhejiang, Jiangsu, Anhui, Hubei, Henan, Guangdong, Gansu and other areas of municipal engineering underground pipeline construction. For example, in the main sewage pipe project of Dongguan City, Guangdong Province, the φ2000mm large cutter disk motor-driven soil pressure balance pipe jacking machine is used to jack 871m, and the φ2400mm large cutter disk motor-driven soil pressure balance pipe jacking machine is used to jack 400m; in Tianjin City, the φ1800mm large cutter disk motor-driven soil pressure balance pipe jacking machine is used to jack 150m of the West Hengtian Pipe Jacking Project, the φ2000mm large cutter disk motor-driven soil pressure balance pipe jacking machine is used to jack φ150m of the Yuijin Road pipe jacking project. 2000mm large cutter disk motor-driven soil pressure balance pipe jacking machine jacking 350m; φ1600mm large cutter disk soil pressure balance pipe jacking machine used in Anhui Bengbu Zhizhun Road sewage pipeline network project, jacking length of 740m; φ1650mm large cutter disk motor-driven soil pressure balance pipe jacking machine used in a city in Gansu natural gas pipeline across the Yellow River project, jacking length of 150m, the bottom of the pipe is buried at a depth of 20m, the crossing stratum is muddy sandstone, the ground layer is muddy sandstone, and the bottom of the pipe is buried at a depth of 20m. The traversing strata are muddy sandstone and mudstone; Zhengzhou Municipal Corporation applies 2 sets of φ2600mm large cutter disk motor-driven soil pressure balance pipe jacking machine for jacking construction, and the cumulative jacking length of each jacking machine is about 3km.
4 Conclusion
Large cutter disk motor-driven soil pressure balance pipe jacking machine has been widely used in our country, and it can be used for the purpose of giving full play to the simple operation of soil pressure balance pipe jacking machine, which is easy to construct and has strong adaptability to the soil strata, In order to give full play to the advantages of simple operation, convenient construction and strong adaptability of soil layer, when used in sandy soil, gravelly soil or strongly weathered sandstone stratum, the power parameter of pipe jacking machine, the life span of the main shaft sealing and the wear-resistance of structural parts (including the cutter) contacting with the sandy soil should be improved and the normal work of lubrication system should be ensured; at the same time, the construction management should be strengthened, the construction process should be emphasized and perfected, and the additive materials should be added into the front side of cutter plate and the soil silo with different ratio and concentration according to the different soil qualities. At the same time, the construction management should be strengthened and the construction process should be improved, and different ratios and concentrations of additive materials should be added to the front of the cutter plate and the soil bin according to the different soil quality.
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