Method for calculating pressure step distance of shallow coal seam covered with thin bedrock

Abstract

The invention discloses a method for calculating the pressure step distance of a shallow coal seam with a thin bedrock. The method comprises the following steps of first, determining bearing reactionsFRA and FRB at two ends of a non-uniform load beam; second, determining the maximum shear stress Taumax of the non-uniform load beam; and third, calculating and determining the pressure step distanceL of a basic roof according to the first formula, wherein in the first formula: h is the thickness of the non-uniform load beam, [Tau] is the ultimate shear strength of the non-uniform load beam, a is the buried depth of a shallow buried end of a cover layer above the non-uniform load beam, b is the buried depth of a deep buried end of the cover layer above the non-uniform load beam, and Gamma isthe average volume force of the cover layer. The invention provides the method for calculating the pressure step distance of the shallow coal bed covered with the thin bedrock.

Description

Technical field [0001] The invention belongs to the technical field of coal mining, and in particular relates to a method for calculating the stepping distance of a thin bedrock shallow coal seam. Background technique [0002] It is generally considered that the buried depth is less than 150 meters, the base load ratio is less than 1, and the roof reflects the structural characteristics of a single key layer. The coal seam with obvious dynamic load is called shallow coal seam. Generally, the bedrock whose thickness is less than 30 meters to 50 meters is called thin bedrock. my country's shallow coal seams are rich in resources, which are mainly distributed in the Yushenfu mining area in my country. Coal plays an important supporting role in its regional economic development. The surface morphology of the area where the working face of Shenfu mining area is located is complex, with ravines vertical and horizontal, deep and steep. In most areas, the coal seam is buried shallow, on...

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Problems solved by technology

[0003] The existing research results have achieved fruitful research results in the fracture and instability of rock formations, but there are few studies on the mechanism of dynamic evolution of mining fractures induced by bedrock fracture and instability during the mining process of thin bedrock and shallow coal seams by gully topography, and The occurrence characteristics of thin bedrock and thick overburden in shallow coal seam make it have special characteristics of mine pressure during mining

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