A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken cha...A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.展开更多
The water abundance of mine floor limestone needs to be solved urgently as the average depth of coal mining in China has increased gradually. A method is presented to discuss water abundance with the numerical and phy...The water abundance of mine floor limestone needs to be solved urgently as the average depth of coal mining in China has increased gradually. A method is presented to discuss water abundance with the numerical and physical layered geoelectrical model being established in the half-space, full-space and full-space with tunnel, respectively. The parameters of water abundance are changed in this study, which includes water quantity, water content and volume of abnormity of water-containing abnormity. Results indicate that the different work fields have different macroscopic influences on the apparent resistivity,and the water abundance parameters of water-containing abnormity have quantitative relationship with the apparent resistivity mean in abnormal regions(three-dimensional space region). The quantitative relationships are shown as following: firstly, the amount of water injection has negative linear correlation with the apparent resistivity mean; secondly, when abnormity is unsaturated, there is a negative power function relationship between water content and apparent resistivity mean; thirdly, the volume of abnormity and apparent resistivity mean behave as a decreasing power function law.展开更多
Under the circumstance that deep mining is increasingly vulnerable to underlying limestone water, accurate detection of floor failure depth ranges at a mining face becomes rather critical to coal mine production in sa...Under the circumstance that deep mining is increasingly vulnerable to underlying limestone water, accurate detection of floor failure depth ranges at a mining face becomes rather critical to coal mine production in safety. Underground borehole fiber optic sensing technology is combined with 2-D parallel electrical surveying to comprehensively monitor and analyze development laws of floor deformation and failure. Moreover, a working face 1022 in a mine of Huaibei Mining Area was taken, for example, introducing the layout of monitoring borehole and installation of relevant sensing units. Based on the stope progress of a working face, data related to strain and geoelectric fields were collected regularly to analyze relationships of field source variation characteristics and strata deformation failures. In this way, the development mechanism of the floor deformation failure can be revealed. As demonstrated by results, the depth failure of the floor at coal seam 10 is calculated to be 15 m, while its disturbance depth turns out to be 22 m. Due to advanced stress, concentrated stope load and post-mining pressure relief, the floor experienced elastic deformation, shear deformation and swelling deformation successively. Without a doubt, testing results obtained have scientific guiding significance for mines with similar geological conditions.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51404013 and 51674008)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining at the China University of Mining and Technology (No. 13KF01)the Natural Science Foundation of Anhui Province (Nos. 1508085ME77 and 1508085QE89)
文摘A water-resistant key strata model of a goaf floor prior to main roof weighting was developed to explore the relationship between water inrush from the floor and main roof weighting. The stress distribution,broken characteristics, and the risk area for water inrush of the water-resistant key strata were analysed using elastic thin plate theory. The formula of the maximum water pressure tolerated by the waterresistant key strata was deduced. The effects of the caved load of the goaf, the goaf size prior to main roof weighting, the advancing distance of the workface or weighting step, and the thickness of the waterresistant key strata on the breaking and instability of the water-resistant key strata were analysed.The results indicate that the water inrush from the floor can be predicted and prevented by controlling the initial or periodic weighting step with measures such as artificial forced caving, thus achieving safe mining conditions above confined aquifers. The findings provide an important theoretical basis for determining water inrush from the floor when mining above confined aquifers.
文摘The water abundance of mine floor limestone needs to be solved urgently as the average depth of coal mining in China has increased gradually. A method is presented to discuss water abundance with the numerical and physical layered geoelectrical model being established in the half-space, full-space and full-space with tunnel, respectively. The parameters of water abundance are changed in this study, which includes water quantity, water content and volume of abnormity of water-containing abnormity. Results indicate that the different work fields have different macroscopic influences on the apparent resistivity,and the water abundance parameters of water-containing abnormity have quantitative relationship with the apparent resistivity mean in abnormal regions(three-dimensional space region). The quantitative relationships are shown as following: firstly, the amount of water injection has negative linear correlation with the apparent resistivity mean; secondly, when abnormity is unsaturated, there is a negative power function relationship between water content and apparent resistivity mean; thirdly, the volume of abnormity and apparent resistivity mean behave as a decreasing power function law.
文摘Under the circumstance that deep mining is increasingly vulnerable to underlying limestone water, accurate detection of floor failure depth ranges at a mining face becomes rather critical to coal mine production in safety. Underground borehole fiber optic sensing technology is combined with 2-D parallel electrical surveying to comprehensively monitor and analyze development laws of floor deformation and failure. Moreover, a working face 1022 in a mine of Huaibei Mining Area was taken, for example, introducing the layout of monitoring borehole and installation of relevant sensing units. Based on the stope progress of a working face, data related to strain and geoelectric fields were collected regularly to analyze relationships of field source variation characteristics and strata deformation failures. In this way, the development mechanism of the floor deformation failure can be revealed. As demonstrated by results, the depth failure of the floor at coal seam 10 is calculated to be 15 m, while its disturbance depth turns out to be 22 m. Due to advanced stress, concentrated stope load and post-mining pressure relief, the floor experienced elastic deformation, shear deformation and swelling deformation successively. Without a doubt, testing results obtained have scientific guiding significance for mines with similar geological conditions.
