A physical structure for reducing mud cake formation on the shield cutter head

Abstract

The present invention provides a physical structure for slowing down the mud cake formation on the shield cutter head, including: a shield cutter head, a shield cutter head panel, and shield cutters. This structure is obtained by modifying the surface of the panel and cutters of the shield cutter head. By setting fine small bumps on the surface of the panel and cutters of the shield cutter head, the bonding effect between the cutter head panel, cutters and the coating is strengthened, and the small bumps are used to exhaust and disperse gas from the soil, improve the soil saturation degree, reduce the soil matrix suction, and further slow down the adsorption effect between clay particles and between clay and the shield cutter head and cutters, ensuring that under the condition that the scouring pressure and flow rate remain unchanged, the mud cake formation on the shield cutter head can be better alleviated and dealt with.

Description

Technical Field

[0001] The present invention belongs to the field of construction engineering, and particularly relates to a physical structure for slowing down the formation of mud cakes on a shield cutter head. Background Art

[0002] With the acceleration of the urbanization development process in China, the load on urban ground traffic facilities has become increasingly serious. The development and utilization of underground space have become the focus of attention of urban designers. The shield tunneling method has been widely used in urban rail transit projects because of its many advantages.

[0003] The shield tunneling method has the advantages of not affecting ground traffic and facilities, not affecting underground pipelines and other facilities, and low construction labor intensity during the construction process. However, the phenomenon of mud cake formation on the shield cutter head often occurs during shield construction, which has an adverse impact on the shield tunneling efficiency, cutter head and cutters, etc.

[0004] When the shield tunneling is carried out in plastic, hard plastic clay formations, mudstone, muddy siltstone and other formations, the soil is rich in clay minerals, with small particle size and high viscosity. The muck cut by the cutters stays between the cutter head and the shield excavation face due to many reasons such as small opening ratio of the cutter head, and forms a thick and hard mud cake under the extrusion of the cutter head, wrapping the cutters, greatly reducing the cutting ability of the cutter head and affecting the tunneling speed. The long-term friction between the cutter head and the face will seriously cause the cutter head to be worn and the temperature to rise continuously, exacerbating the formation of the mud cake.

[0005] In order to reduce the problem of mud cake formation on the shield cutter head, construction units often take measures such as using dispersants, improving the cutter head panel flushing system, and coating treatment on the cutter surface. However, these methods often have certain limitations and can only provide references for the mud cake formation problem under the same engineering background. The differences in geological environment may also cause these methods to not play an efficient role. For example: the coating material is extremely easy to fall off, causing wear to the cutters and resulting in mud cake formation; due to site restrictions, the flushing pressure is not enough to flush the mud cake that has formed on the cutter head; in formations such as silty clay, the use effect of the dispersant is not good, etc. Summary of the Invention

[0006] In view of some existing or potential problems in the measures for the mud cake formation problem on the shield cutter head, the present invention provides a physical structure for slowing down the formation of mud cakes on the shield cutter head. This structure is obtained by transforming the surface of the panel cutters of the shield cutter head. The transformation measures are based on the microscopic mechanism of soil adsorption on the cutter head and are implemented with reference to the non-stick pan principle.

[0007] The technical solution of the present invention is as follows:

[0008] A physical structure for slowing down the mud cake formation on the shield cutter head, comprising: a shield cutter head, a shield cutter head panel, and shield cutters. The surfaces of the shield cutter head panel and the shield cutters on the side facing the excavated soil layer are distributed with bumps;

[0009] The protrusion height of the bumps and the intervals between the bumps can be reasonably set according to the actual mud formation situation of the shield machine in actual projects, forming regular patterns on the shield cutter head panel and the shield cutters;

[0010] Generally, the mud formation phenomenon on the shield cutter head is most serious at the center position of the cutter head. Therefore, the setting of the protrusion height of the bumps on the shield cutter head panel is as follows: from the center of the cutter head to the periphery, it is distributed from high to low (distributed from high to low within the height range of 0.5 - 0.8 mm); the interval form between the bumps on the shield cutter head panel is as follows: from the center of the cutter head to the periphery, it is distributed from dense to sparse (distributed from dense to sparse within the interval range of 0.5 - 0.9 mm); the setting method of the bumps on the shield cutters is the same as that on the shield cutter head panel, that is: in the central area of the cutter head with serious mud formation, the bumps are set in a high and dense manner, and in the surrounding areas with slight mud formation, the bumps are set in a low and sparse manner;

[0011] The forming process of the bumps is as follows: using molten iron, pouring the molten iron into the feeding cylinder of the die-casting machine, and then the piston injection pushes the molten iron into the die-casting mold, standing for 10 - 15 seconds, die-casting forming, and then carrying out burr treatment and sandblasting treatment to form;

[0012] Furthermore, a TiAlN coating is also provided on the surfaces of the shield cutter head panel and the shield cutters distributed with bumps.

[0013] The advantages of the present invention are:

[0014] (1) From a microscopic perspective, the problem of mud cake formation on the shield cutter head is explored. The adhesion force between clay and the metal surface is mainly affected by the matrix suction (i.e., the hydraulic pressure difference in the soil), and this matrix suction promotes the adsorption between clay particles and between clay and the metal surface. The setting of small bumps can change the vacuum state between the soil body and the cutter head panel and the cutters, play a role in exhausting and dispersing gas from the soil body, improve the soil saturation, reduce the soil matrix suction, and further slow down the adsorption between clay particles and between clay and the cutter head panel and the cutters.

[0015] (2) The setting of small bumps on the shield cutter head can strengthen the bonding effect between the coating and the metal surface of the shield cutter head, make the coating not easy to fall off during the shield process, extend the service life of the coating, reduce the wear of the cutters, and further slow down the generation of mud formation on the shield cutter head panel and the cutters.

[0016] (3) The provision of small bumps on the shield cutter head can reduce the contact area between the shield cutter head and the soil mass, and can also slow down the formation of mud caking on the shield cutter head.

[0017] (4) The TiAlN coating material has the advantages of improving the oxidation resistance and anti-adhesion ability of the shield cutter head panel and the cutters, and is not easy to fall off. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic physical structure diagram for slowing down mud caking on the shield cutter head of the present invention;

[0019] Figure 2 It is an enlarged structure diagram of part A of the shield cutter head panel;

[0020] Figure 3 It is an enlarged structure diagram of part B of the shield cutter;

[0021] In the figure: 1 - shield cutter head, 2 - shield cutter head panel, 3 - shield cutter, 4 - bumps on the panel and the cutter. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below with reference to the accompanying drawings through specific embodiments, but the protection scope of the present invention is not limited thereto.

[0023] Embodiment 1

[0024] A physical structure for slowing down mud caking on the shield cutter head is obtained by modifying the components on the shield cutter head 1. The modified parts include the shield cutter head panel 2 and the shield cutter 3. Dense small bumps 4 are provided on the metal surface on the side of the shield cutter head panel 2 and the shield cutter 3 facing the excavated soil layer.

[0025] The protrusion height of the small bumps 4 on the panel 2 and the cutter 3 and the intervals between them are reasonably set according to the actual mud caking situation of the shield machine in actual projects. The protrusion height of the small bumps 4 on the shield cutter head panel 2 is higher at the center of the cutter head than at the position far from the center of the cutter head; the interval form between the small bumps 4 on the shield cutter head panel 2 is dense in the middle and sparse around. The setting method of the small bumps 4 on the shield cutter 3 is the same as that on the shield cutter head panel 2, that is: in the area with serious mud caking, the small bumps are set in a high and dense manner, and in the area with slight mud caking, they are set in a low and sparse manner, forming a regular pattern.

[0026] From a construction perspective, generally, the coating material on the surface of the shield cutter 3 is extremely likely to fall off during the shield construction process, resulting in friction between the shield cutter 3 and clay particles, causing damage to the cutter, and promoting the deterioration of the mud caking phenomenon on the shield cutter head 1. However, the setting of the small bumps 4 on the shield cutter 3 can strengthen the bonding effect between the surface of the shield cutter 3 and the coating, extend the service life of the coating, reduce the wear of the cutter 3 during the shield process, and play a role in slowing down the generation of the mud caking phenomenon on the shield cutter head panel 2 and the cutter 3.

[0027] From a microscopic perspective of dealing with the mud caking on the shield cutter head 1, during the shield tunneling process, the small bumps 4 are used to exhaust and disperse the gas in the soil, improve the soil saturation, reduce the soil matrix suction, and further slow down the adsorption effect between clay particles and between clay and the shield cutter head panel 2 and the cutter 3, reduce the shear strength of the soil-structure contact surface, and ensure that under the condition that the scouring pressure and flow rate remain unchanged, the mud caking problem on the shield cutter head panel 2 and the shield cutter 3 can be better alleviated and addressed.

[0028] From the perspective of the effect of slowing down the mud caking on the shield cutter head panel and the cutter, this physical transformation scheme can effectively reduce the degree of mud caking on the shield cutter head 1 when the shield machine tunnels in the clay mineral-rich formation.

Claims

1. A physical structure for reducing mud cake formation on a shield cutter head, comprising: a shield cutter head, a shield cutter head panel, and shield cutters, characterized in that bumps are distributed on the surfaces of the shield cutter head panel and the shield cutters on the side facing the excavated soil layer; The setting of the protrusion height of the bumps on the shield cutter head panel is as follows: it is distributed from high to low from the center of the cutter head to the periphery; the spacing form between the bumps on the shield cutter head panel is as follows: it is distributed from dense to sparse from the center of the cutter head to the periphery; the setting method of the bumps on the shield cutters is the same as that on the shield cutter head panel, that is: in the central area of the cutter head, the bumps are set in a high and dense manner, and in the surrounding area, the bumps are set in a low and sparse manner; The forming process of the bumps is as follows: using molten iron, pouring the iron water into the feeding cylinder of a die-casting machine, then the piston injection pushes the iron water into the die-casting mold, standing for 10 - 15 seconds, die-casting forming, and then carrying out burr treatment and sandblasting treatment to form.

2. The physical structure for reducing mud cake formation on a shield cutter head according to claim 1, characterized in that, on the shield cutter head panel or the shield cutters, the bumps are distributed from high to low within the height range of 0.5 - 0.8 mm and from dense to sparse within the spacing range of 0.5 - 0.9 mm.

3. The physical structure for reducing mud cake formation on a shield cutter head according to claim 1, characterized in that, a TiAlN coating is provided on the surfaces of the shield cutter head panel and the shield cutters where the bumps are distributed.

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