A Method of Determining the Depth of Sliding Slabs in Coal Wall and Its Slipping Risk

Abstract

The invention discloses a method for determining the depth and slip risk of a coal wall slip sheet. The method includes assuming n circle centers of heights yi (i = 1, 2, 3,..., n) far from a top plate and n slip arc radius Rj (j = 1, 2, 3,..., n), defining n*n slip surface Sij according to the yi and Rj, and figuring out a risk coefficient Kij; acquiring a slip risk coefficient curved surface K of the n*n slip surface Sij, and acquiring a curve Kcr=1 by means of the intersection of a plane K=1 and the curved surface K; defining the slip surface depth d as the distance between the intersection of the slip surface and top plate and a coal wall, acquiring a curved surface of the slip surface depth d of the n*n slip surface Sij, and acquiring a curve of a critical slip depth dcr by projecting the curve Kcr = 1 to the curved surface d; figuring out a maximum value dcrmax (ycr, Rcr) of the curve dcr, determining a slip surface as the maximum depth critical slip surface according to the ycr and Rcr, and allowing the value dcrmax to be the depth of the coal wall slip sheet. The method is used for designing and developing control implementation and parameters of the coal wall slip sheet according to the depth during the coal wall management of working face with large mining height.

Description

technical field [0001] The invention belongs to the technical field of surrounding rock control in a coal mining working face, and in particular relates to a method for determining the depth of a coal wall slipping side of a mining working face and the risk of slipping. Background technique [0002] Thick and extra-thick coal seams account for about 40% of my country's coal resources. At present, the primary mining height of large mining height fully mechanized mining is 3.5~7.0m, and the primary mining thickness of large mining height fully mechanized caving is 5~20m, of which the bottom coal cutting height is 3~7.0m. 5m. However, practice has proved that due to the increase of the height of the coal wall in the fully mechanized mining / caving face with large mining height, the mine pressure is more severe, especially the coal wall spallation is very easy to occur. Severe coal wall spalling not only affects the normal production of the working face, but also threatens the li...

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Problems solved by technology

[0003] In terms of coal wall flaking, the existing research results mostly focus on the analysis of factors affecting coal wall flaking, the study of flaking mechanism, the method of flaking, the form and type of flaking, and the technical measures to prevent and control coal wall flaking. There is no systematic and effective method for predicting the depth of coal wall spalling and its evaluation of the risk of slippage. This situation directly limits the accurate determination of the method of controlling coal wall spalling and its parameters.

The document "Mechanism and Control Technology of Coal Wall Fragmentation in Fully Mechanized Mining Faces with Large Mining Height" (Coal Science and Technology, 2008, 36 (9): 1-3, 24) adopts the Coulomb-Molar strength theory to obtain the compression-shear coal The formula for calculating the maximum depth of the wall side is Δa=M tan(45 ° - φ / 2) and the calculation formula for the maximum depth of the sliding coal wall side is Δb=M tan(90 ° - φ ), it can be seen that only the coal wall height M and the internal friction angle of coal are considered in this calculation formula φ , the factors considered are single, and the predicted value is quite different from the actual side depth

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