Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at th...Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at the Shendong Mine. We have selected the height of the water-conducting fracture zone in overlying strata as a composite index and established the applicable conditions of aquifer-protective mining in shallow coal seams with a multi-factor synthetic-index classification method. From our calculations and analyses of variance, we used factors such as the overlying strata strength, mining disturbing factors and rock integrity as related factors of the composite index. We have classified the applicable conditions of aquifer-protective mining in shallow coal seams into seven types by comparing the result of the height of water-conducting fractured zones of long-wall and short-wall working faces with the thickness of the bedrock, the thickness of the weathered zone and the size of safety coal-rock pillars. As a result, we propose the preliminary classification system of aquifer-protective mining in shallow coal seams. It can provide a theoretical guidance for safe applications of aquifer-protective mining technology in shallow coal seams under similar conditions.展开更多
A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high e...A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high efficiency for the mining field in west China. This classification was suitable for shallow coal seams with different thickness and was beneficial to the local environmental protection. Using the 3-Universal Distinct Element Code （3DEC） numerical software, the height of the fractured zones for shallow coal seams with thin bedrock was calculated and analyzed, and its predicting formula was achieved. Meanwhile, according to the lithology and the weathering degree of the shallow coal seam the thickness of the protective layer was determined as 10 m and the overlying water body of loose water-bearing sand for shallow coal seams with thin bedrock was divided into three types, namely, weak, medium and strong. Based on these, the necessary bedrock thickness of the Iongwall coalface for shallow coal seams with thin bedrock was confined according to the different mining height and water yield nature of the overlying loose water-bearing sand. Combined with the present mining status, a set of new methods of adaptable conditions classification of aquifer-protective mining technology in the Iongwall coalface for shallow coal seams with thin bedrock was put forward.展开更多
Unsystematic selection and planting of tree seedlings in road borders, forest regeneration, development of parks and green spaces which are incompatible with the given climate zone, is a kind of interference and viola...Unsystematic selection and planting of tree seedlings in road borders, forest regeneration, development of parks and green spaces which are incompatible with the given climate zone, is a kind of interference and violation of ecosystem privacy. Therefore, the stability and persistence of species in the forest protection is important for planners of natural resources. Field station of spreading Dehloran aquifer is one of the major forestations in Ilam province. It aimed of protecting the soil and underground water table feeding in hot dry plains of Mosian, which have been planted with native and non-native species. In the present article 100 trees of each species were planted during the years 1998 and 1999 in the station, such as Ziziphus spina-christi, Prosopis juliflora, Eucalyptus camaldulensis and Acacia sp. They were randomly selected and information about this species measured and recorded annually has been used. Finally the data has been analysis; by comparison test to compare the growth and persistence. Results indicate that despite high average in height growth （85.4 cm/year） and relatively large diameter growth （2.43 cm/year）, non-native species of Eucalyptus are not in good condition in terms of viability （36.2 percent） and freshness. On the contrary, the native species of Ziziphus with relatively low in average height and diameter growth （22.64 and 2.28 cm/year respectively） represent a better index of viability （65.4 percent） and freshness.展开更多
基金Financial support for this work, provided by the research fund of the North China Institute of Science and Technology (No.A09002)the National Natural Science Foundation of China (No.50834005)the National Basic Research Program of China (No.2007CB209402)
文摘Based on the conclusions of domestic and foreign research, we have analyzed the collapse-fall characteristics of overlying strata and the mechanism of aquifer-protective mining in shallow coal seam working faces at the Shendong Mine. We have selected the height of the water-conducting fracture zone in overlying strata as a composite index and established the applicable conditions of aquifer-protective mining in shallow coal seams with a multi-factor synthetic-index classification method. From our calculations and analyses of variance, we used factors such as the overlying strata strength, mining disturbing factors and rock integrity as related factors of the composite index. We have classified the applicable conditions of aquifer-protective mining in shallow coal seams into seven types by comparing the result of the height of water-conducting fractured zones of long-wall and short-wall working faces with the thickness of the bedrock, the thickness of the weathered zone and the size of safety coal-rock pillars. As a result, we propose the preliminary classification system of aquifer-protective mining in shallow coal seams. It can provide a theoretical guidance for safe applications of aquifer-protective mining technology in shallow coal seams under similar conditions.
基金Supported by National Natural Science Foundation of China(50904063)the 2007 Research Fund of the State Key Laboratory of Coal Resources and Mine Safety(07KF09)Scientific Research Foundation of China University of Mining & Technology(2008A003,2005B002)
文摘A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high efficiency for the mining field in west China. This classification was suitable for shallow coal seams with different thickness and was beneficial to the local environmental protection. Using the 3-Universal Distinct Element Code （3DEC） numerical software, the height of the fractured zones for shallow coal seams with thin bedrock was calculated and analyzed, and its predicting formula was achieved. Meanwhile, according to the lithology and the weathering degree of the shallow coal seam the thickness of the protective layer was determined as 10 m and the overlying water body of loose water-bearing sand for shallow coal seams with thin bedrock was divided into three types, namely, weak, medium and strong. Based on these, the necessary bedrock thickness of the Iongwall coalface for shallow coal seams with thin bedrock was confined according to the different mining height and water yield nature of the overlying loose water-bearing sand. Combined with the present mining status, a set of new methods of adaptable conditions classification of aquifer-protective mining technology in the Iongwall coalface for shallow coal seams with thin bedrock was put forward.
文摘Unsystematic selection and planting of tree seedlings in road borders, forest regeneration, development of parks and green spaces which are incompatible with the given climate zone, is a kind of interference and violation of ecosystem privacy. Therefore, the stability and persistence of species in the forest protection is important for planners of natural resources. Field station of spreading Dehloran aquifer is one of the major forestations in Ilam province. It aimed of protecting the soil and underground water table feeding in hot dry plains of Mosian, which have been planted with native and non-native species. In the present article 100 trees of each species were planted during the years 1998 and 1999 in the station, such as Ziziphus spina-christi, Prosopis juliflora, Eucalyptus camaldulensis and Acacia sp. They were randomly selected and information about this species measured and recorded annually has been used. Finally the data has been analysis; by comparison test to compare the growth and persistence. Results indicate that despite high average in height growth （85.4 cm/year） and relatively large diameter growth （2.43 cm/year）, non-native species of Eucalyptus are not in good condition in terms of viability （36.2 percent） and freshness. On the contrary, the native species of Ziziphus with relatively low in average height and diameter growth （22.64 and 2.28 cm/year respectively） represent a better index of viability （65.4 percent） and freshness.
