A Simplified Method for Predicting the Distribution of Earth Pressure in Water-rich Sand Layer at the Cutterhead Opening

Abstract

The invention belongs to the technical field of underground engineering, and the method comprises the four steps: calculating the height of a liquid-plastic interface in a soil bin, calculating a real-time soil pressure distribution function on the back face of the soil bin, calculating the resultant force of cutter head opening soil pressure and calculating real-time cutter head opening pressureboundary distribution. Therefore, flowing of a muck mixture in a soil bin under the cutting influence of a spiral conveyor is simplified into sliding of soil blocks, the slope angle of a sliding surface is approximate to geometric parameters of a bus of a blade of the spiral conveyor, and the height of a liquid-plastic interface in the soil bin is calculated according to the soil discharging rateof the spiral conveyor. Theoretical approximate calculation of the soil pressure distribution of the water-rich sand layer at the opening of the cutterhead is realized from the perspectives of stressbalance and material balance. The method is suitable for approximate calculation of the soil pressure at the opening of the cutterhead of the water-rich sand layer, the actual soil pressure approximate value at the opening of the cutterhead can be calculated according to shield tunneling actual measurement parameters, and the method has important significance in risk assessment, stratum loss earlywarning and the like of shield construction.

Description

technical field [0001] The invention belongs to shield machine construction technology, in particular to a calculation method for estimating the soil pressure distribution of a water-rich sand layer at an opening of a cutterhead, and belongs to the technical field of underground engineering. Background technique [0002] At the opening of the cutter head of the earth pressure balance type shield, the sliding force generated by the self-weight of the face is balanced by the counter force provided by the inside of the soil bin to achieve stratum stability. However, the formation water and soil pressure at the cutter head opening is difficult to be accurately measured by sensors. The soil pressure sensor arranged on the back of the soil bin reflects the water and soil pressure distribution on the back of the soil bin, which is not equal to the internal reaction force of the soil bin at the opening of the cutterhead. [0003] 1 (A device and method for monitoring earth pressure...

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Problems solved by technology

[0003] 1 (A device and method for monitoring earth pressure on the excavation surface of a model shield machine, application number: 201810197379.8) proposes a method of setting a sensor on the cutter head to prevent the data cable from being damaged by the rotation of the cutter head through wireless transmission and reception method, but because the sensor is set on the cutter head, it reflects the formation water and soil pressure in the unopened area of ​​the cutter head. For the formation water and soil pressure, the unopened area of ​​the cutter head is a rigid-elastic boundary while the open area of ​​the cutter head is plastic. -Flow boundary, so the formation water and soil pressure in the unopened area of ​​the cutter head is different from the size and distribution form of the formation water and soil pressure in the open area of ​​the cutter head, so the pressure sensor installed in the unopened area of ​​the cutter head cannot measure the opening of the cutter head Formation water and soil pressure at

[0004] 2 (Wu Li. Research on the pressure balance mechanism of shield tunneling chamber based on discrete element simulation [D]. Dalian University of Technology, 2009.) and 3 (Liu Chang. Research on the key technology of pressure control in earth pressure balance shield tunneling chamber [D]. Dalian University of Technology, 2012.) used the discrete element numerical simulation method to study the pressure transfer characteristics of the airtight cabin, and proposed a statistical calculation method for the pressure difference between the excavation surface and the airtight cabin partition on the basis of the statistics of the simulation analysis results. The research results prove that the pressure on the back of the soil bin is not greater than the water and soil pressure at the opening of the cutter head. However, due to the numerical simulation method, no explicit derivation based on the force analysis can be given, so it cannot rise to the theoretical height. Unable to give theoretical formulas, it is difficult to generalize quantitative conclusions to general situations

[0005] 4 (Liu Bo, Li Shouju. Earth Pressure Balance Shield Machine Sealed Cabin Earth Pressure Control Model [J]. Tunnel Construction, 2010, 30(04): 388-391+450.) Analysis of screw machine discharge through mechanical modeling However, when analyzing the soil stability at the opening of the cutter head, the pressure transfer characteristics of the soil bin are ignored, and the passive earth pressure distribution at the opening is directly replaced by the readings of the soil pressure sensor on the back of the soil bin, which violates the The law that the pressure on the back side is not greater than the water and soil pressure of the formation at the opening of the cutter head

[0006] The current results do not provide the sensor measurement method for the water and soil pressure at the opening of the shield cutter head, and the research on the pressure transfer characteristics in the soil chamber is limited to the statistical analysis of the computer simulation results and lacks the theoretical calculation formula. A simplified calculation method for calculating the support force of the mixture inside the soil bin at the opening of the cutter head on the tunnel face based on the measured shield tunneling parameters of the mold

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