Correct selection of shield tunneling tool shape and layout

source：http://www.xrocktools.com/ Release Time：2015-09-11 15:12:16

There are many factors that affect the operation of shield tunneling machines, and the torque coefficient of the shield tunneling machine cutterhead is an important parameter in the design of shield tunneling machines. In addition, the shape and arrangement of the cutterhead tools are also important factors. The arrangement and shape of shield tunneling tools are very important in the design of shield tunneling machines. The layout and shape of the cutting tools are suitable for the geological conditions of the application project, which directly affects the cutting effect, excavation condition, and excavation speed of the shield machine.

For the spoke type cutterhead for full section cutting, there are two ways of tool arrangement from the development history of shield tunneling machines: the first is the continuous arrangement of the cutting tools as a whole. Due to its high cutting resistance, the flowability of the soil inside the sealed compartment of the shield tunneling machine is poor, and it is rarely used now, only occasionally used in muddy formations with low cutting resistance; The second method is the staggered and continuous arrangement of tool teeth, which is widely used due to its low cutting resistance, high cutting efficiency, good flowability of soil in sealed chambers, and easy mixing. At present, the world generally adopts a staggered and continuous arrangement of dental shapes. The cutting tool arrangement of the shield tunneling machine purchased by our group company adopts this method. According to the three main geological conditions that may be encountered during the construction of subway tunnels in Beijing, the arrangement of cutting tools should be based on the principle of staggered and continuous tooth patterns to ensure that the cutting trajectory of the shield machine cutting tool covers the entire excavation section; In addition, for different cutting requirements (including geological requirements), several types of cutting tools such as cutting knives, advance knives, disc ring shell knives, fish tail knives, and imitation knives need to be set up.

As mentioned earlier, the shape and function of the cutting tool must adapt to the characteristics of the construction geology, and its function and requirements are different at different positions of the cutting section. Therefore, the design of the cutting tool should be carried out. In response to the characteristics of Beijing subway tunnels crossing three main geological strata, the following factors should be considered when designing cutting tools The cutting efficiency of cutting tools in sand and gravel formations, that is, how to reduce cutting resistance and ensure the fluidity of cutting soil By changing the shape of the cutting tool, the wear and tear of the tool during excavation can be reduced, and the durability of the tool can be improved To meet the needs of construction in the bustling areas of 365JT city, efforts should be made to minimize the interference of the rotating cutting tool of the cutterhead on the surrounding soil and environment, such as vibration, noise, etc How to propose practical and feasible measures from the aspects of materials and design to solve the wear and tear of cutting tools (including impact and falling blocks) during shield tunneling in sandy and gravel formations, ensuring the reliability of shield tunneling tools for long-distance excavation.

At present, shield tunneling tools are generally classified into two types based on cutting principles: rolling cutters and cutting cutters (these two types of tools can be further subdivided according to the different properties of tunnel surrounding rock and cutting purposes). The cutting principle of the rolling cutter is mainly that the tool relies on compression to break through the rock, and is generally used for the excavation of rock tunnels. When there are large gravel particles (with a particle size greater than 400mm) that pass through loose strata and reach a certain proportion, a rolling cutter type tool can also be used. In cases where the geological conditions of the tunnel are complex and varied, and the rock (not too strong) frequently intersects with the general soil (or clay or sand), it is also possible to use roller cutters, which are used in composite shield tunneling machines. The cutting principle of the cutting tool is mainly that while the shield machine advances forward, the tool rotates with the cutterhead to generate axial (along the direction of tunnel advancement) shear force and radial (tangential direction of cutterhead rotation) cutting force on the soil in front of the excavation face, continuously cutting the soil in front of the excavation face. Cutting knives are generally suitable for loose formations such as sand, gravel, sand, clay, etc. with particle sizes less than 400mm.

An>n s p>pA t-family: Song typeface; MSO ASCII font family: Salibri; MSO HANSI font family: Salibri '>Mastering and proficiently using various cutting tools, implementing planned tool inspections and replacements, and being able to timely understand, master, and analyze the usage status of cutting tools are of great significance for effective use of cutting tools and effective protection of tool heads.

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