First, the reason for delineating the security pillar 
When deposits or the upper edge of rivers, lakes and the like railway, the mining deposits affect its safety; in some special cases, and near to develop roadway or the building can not all bands disposed outside of the mobile , must maintain a security pillar, its role: to protect the surface buildings and wellbore.
Second, the security method of the pillars and steps
The delineation of the security pillar is based on the required safety distance, and the range of the protection zone is drawn along its periphery. Then, starting from the periphery of the protection zone, the moving boundary line is drawn downward according to the selected rock movement angle. The scope of the ore body is the security pillar.
(1) On the geological plan, the location and area of ​​industrial buildings such as wellbore and hoisting machinery rooms are circled. According to the safety distance of the protection level, the protection range is drawn around;
(2) Cross-section geological map I—I along the center of the wellbore for the vertical ore body trend, marking the range of the wellbore and buildings, and the width of the seat belt, and plotting the thickness, inclination and geological structure of the ore body and each rock formation. In order to ensure sufficient accuracy, two cross-sectional geological maps I'-I', I-"-I" should be made on both sides of the wellbore.
(3) A longitudinal section geological map II-II parallel to the ore body along the center of the wellbore, indicating the range of the wellbore and building, and the width of the seat belt. In order to ensure the accuracy, two longitudinal profiles geological maps II'-II', II"-II" are made on the upper and lower sides of the wellbore protection belt.
(5) In the longitudinal section, the value of the flank movement angle δ of the ore body and each rock layer is plotted. The mapping method steps are the same as the cross section, and the intersections of the moving line and the top and bottom plates of the ore body are obtained, C1, C Ì1, d1, d Ì1 and A1, B1 and d2, d Ì2, C2, C Ì2 and the like. The points C1, ... C2, C Ì2 and other points are drawn on the geological plan, and the intersections on the upper and lower sides of the left and right sides are respectively connected to obtain the moving range on the ore body and the security pillar boundary. line.
(6) The A1-A2, A Ì1-A Ì2 of the ore body roof along the strike direction intersects with the boundary line C1-C2, C Ì1-C Ì2 along the oblique direction, and the ore roof safety pillar range is obtained. In the same way, the safe pillar range of the ore body floor can be obtained. If the wellbore is placed in the ore body, in addition to the security pillars near the wellbore, the security pillars of the road or railway leading to the wellbore are reserved.
The security pillar ore is difficult to recover. Even if the mining is completed, the ore recovery rate is low, the labor productivity is not high, the safety conditions are poor, and the cost is high. Therefore, it is necessary to keep the wellbore of the security pillar, and it is better to choose a section with a thin or low grade of the ore body, so that even if it does not return to the mining column, the economic loss is not large.
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