| The large-scale development of coal resources has played an important supporting role in China’s economic construction and social development.However,the land resource damage,ecological landscape damage,frequent geological disasters and other environmental problems caused by the collapse of coal mine goaf are becoming more and more serious.Therefore,the reclamation and development and utilization of the subsided land in goaf are widely concerned by the outside world.Restricted by internal factors and external environment,there are different types of subsidence land in coal mine goaf,and the land use patterns of different types of subsidence land are also different.In order to select the matching land use mode,realize the effective utilization of land resources in the subsidence area,and promote the construction of green mines in China,the collapse area of typical goaf in Jinzhong City,Shanxi Province is taken as the research object in this paper.This paper uses analytic hierarchy process(AHP)to classify the types of subsidence land in goaf and study the development and utilization mode matching with the type of subsidence land This paper uses the method of entropy weight extension matter-element model and multi index comprehensive evaluation to evaluate the reclamation suitability of the matching development and utilization mode in the study area,verifies the matching results,and comprehensively determines the development and utilization mode type of the research area.The results are as follows:(1)A five level classification system for the types of subsided land in coal mine goaf is established,and the classification method and the corresponding classification basis and standards are determined.Eight indexes,including collapse area(u11),collapse morphology(u12),collapse depth(u13),stability(u14),ground undulation(u15),ponding characteristics(u21),ponding depth(u22)and ponding water quality(u23)were selected by classification.The analytic hierarchy process(AHP)was used to determine the weights of each index The weights values of each index were 0.216 6,0.338 8,0.054 8,0.100 0,0.5000,0.500 0.The order of weight of each index layer is:u12>u11>u14>u21>u13=u15>u22=u23.And determine the level size by sorting the weight value.The results are as follows:"the first level" can be divided into four first-class types:V-type,trough type,bowl type and basin type according to the collapse form;"the second level" can be divided into four secondary types:large area,sub large area,medium area and small area according to the collapse area;"the third level" can be divided into three tertiary types according to the stability of the collapse land:stable,basically stable and unstable;According to the characteristics of water accumulation,"the fourth level" can be divided into three fourth level types:perennial water accumulation,seasonal water accumulation and non waterlogged subsidence land;"the fifth level" can be divided into 15 five grade types according to the surface relief and collapse depth for the non waterlogged subsidence land,and 18 five grade types according to the water depth and water quality of the water accumulated.This study provides a scientific basis for the development and utilization of the mined out area.(2)According to the classification system and related standards of the subsided land in the goaf of coal mine,the development and utilization modes of the subsided land are systematically summarized,and the structural requirements and treatment measures of each mode are put forward.It includes five types:cultivated land model,forest and grassland land use mode,construction land model,water land use mode and other land use mode.The cultivated land use pattern can be divided into dry land use mode,irrigated land use mode and paddy field land use mode;water area land use mode can be divided into aquaculture constructed wetland,landscape type constructed wetland,purification type constructed wetland and plain reservoir mode;other land use modes include landfill mode,Geopark mode and ecological industry mode.(3)The matching relationship between the types of subsidence land and the development and utilization mode of coal mine goaf is constructed,and the suitability evaluation standards and methods of entropy weight extension matter-element model and multi index comprehensive evaluation are determined,which provides scientific basis for selecting the most reasonable land use mode according to local conditions and realizing the most effective utilization of land in different subsidence areas.(4)According to the above research results,the types of coal mine goaf subsidence land in Shanxi Jinzhong No.3 mining area are determined,and the suitable land development and utilization modes are all cultivated land use modes.The suitability of cultivated land use pattern was verified by using entropy weight extension matter-element model and index comprehensive evaluation method.The results of entropy weight method showed that:the surface relief(0.515 8),road condition(0.355 4),terrain slope(0.063 7),collapse depth(0.047 3)and location condition(0.013 4)are the main influencing factors of the suitability of land reclamation for cultivated land in the third mining area of Jinzhong City.The results are in accordance with the actual situation of the region The results of entropy weight extension matter-element model evaluation show that the comprehensive correlation degree of Jinzhong coal mine subsidence area,Wenjiagou coal mine subsidence area and Fodiangou coal mine subsidence area is 0.084 9,0.195 4 and 0.418 1 respectively.The suitability evaluation levels of reclamation for cultivated land were "moderate suitability","barely suitable" and "unsuitable".The results of multi index comprehensive evaluation showed that the comprehensive index of reclamation suitability of coal mining subsidence land was ranked as Jinzhong coal mine subsidence area(0.5160),Wenjiagou coal mine collapse area(0.341 0),fudangou coal mine subsidence area(-0.857 0).The results of the two methods are consistent and reliable.Jinzhong coal mine subsidence area and Wenjiagou coal mine subsidence area are consistent with the verification results,which can be reclaimed into cultivated land mode by taking land remediation engineering measures.Because of the local social and economic development characteristics,the location and road conditions can not be improved in a short time.Therefore,the subsided land in the mining area is not suitable for use as cultivated land,and other uses can be considered.In a word,the research on the relationship between the system classification and the development and utilization pattern matching of the coal mine goaf subsidence area can be used for different types of coal mine goaf subsidence area.The research provides a certain scientific basis,but the specific problems need to be analyzed in detail.The selection of each mode needs to consider the local social and economic conditions.Therefore,it is necessary to verify its suitability and conduct comprehensive analysis through the evaluation method of entropy weight extension matter-element model and index comprehensive evaluation. |
