| The contradictions have manifested itself between China's infinite demand of coal and the limited resources gradually , and the coal, as the main energy, new alternative energy sources can not be replaced. It is necessary to save coal resources and improve the recovery rate. There is a large area of workable bed on the top of mined-out region in existing production mining. It is significant for building a conservation-minded society and the promotion of sustainable development of the national economy to recover this coal scientifically and rationally.Recovery of abandoned coal seam on the top of mined-out area is essentially the ascending mining of coal reserve. Coal mining formed the damage zone in the roof strata is usually much larger than in the floor strata. Therefore, in order to reduce the disturbance on mining the close coal seam, mining taken in descending order is adopted almost in practice. Correspondingly, the theoretical and technical studies are carried out mainly for the descending mining. Researches related on ascending mining are concentrated on the coal seam spacing only considered Experiential and Feasibility Test Methods influenced by the lower part of coal mining and mining pressure observation analysis. In fact the core issue of ascending mining is the laws of upper coal floor movement and deformation under influence of upper coal seam mining upon lower coal seam mining depending on the structure between the rock strata. Thus, research on the structure between the rock strata in ascending mining of coal reserve and the laws of upper coal floor movement provide a sound basis for further research in the future and promote the development of ascending mining technology and efficient recovery of the abandoned mining coal seam, which has an important part on the theoretical guidance.In this paper, the research is made from the structure between the rock strata in ascending mining of coal reserve and the laws of upper coal floor movement through a combination of methods such as the experimental research. These are researched systemically, concluding the structure between the rock strata in ascending mining,experiential and feasibility test methods,the laws of upper coal floor movement and deformation and the control system technology of mining pressure residual in ascending mining of coal reserve. The main research content and results are as follows:(1)on account of the ascending mining of coal reserve,separating two ways of caving mining and pillar supporting mining, making a research on the evolution law of the structure between the rock strata, stress distribution of surrounding rocks and the movement and deformation laws between the rock strata. The study found: the control stratum existed between the rock strata in ascending mining. After failure of interlayer in the ascending mining with the method of coal reserve of caving mining , as a result of dilatancy effect ,broken blocks arranged orderly and strained against another formed beams----semi-arch structure, half part of which semi-arch is at the top of mined-out area with extrusion block structure of the surface-to-surface contact which axis (that is, the role of power transmission lines) is a curve ; the structure of block beam is similar with the structure of beam formed by straining against broken blocks of each other in the central of upper mined-out area despite the cracks but not losing the overall structure. The top of rocks maintain the good integrity and macro-continuity and present a typical beam and plate structure. As far as displacement of sinking is concerned, the point with maximum displacement is located above the middle of the lower gob area. The amount of displacement on both sides decreases with the increase of out-of- center distance. The breaking caving rocks forms a typical"deformed basin", while curve showing the sinking of upper no- carving rocks will form waviness of partial basin. Lower hard ones of interlayer rocks can easily become the control layer of them. As for ascending mining of remaining coal reserve with pillar support, stump undertakes the load from the upper rock leading to a malconformation---------"strong stump with weak carrying capacity"and"weak stump with strong carrying capacity",namely stump with weak carrying capacity has more capacity of carrying loads from rock beam, and vice versa. This leads to compressive deformation and shear fracture to the weak stump and tensile failure to the rock beam on the edge of the strong stump, which form a caving zone. The rock with no break on the top can maintain the original state of integrity and continuity and form a typical beam and plate structure.(2) Based on analog simulation experiment, with a combination of rock mechanics, block theory, elastic-plastic mechanics and structural mechanics, sphere of influence on the interlayer rock by exploitation of the lower coal seam is analyzed and acquired; mechanical models of interlayer rock structure through ascending mining with caving and pillar supporting are respectively established and analyzed; mechanisms of ascending mining with caving and pillar supporting mining are analyzed and verified by numerical simulation.(3) On account of interlayer of coal reserve in ascending mining, through theoretical deduction ,research on the impact of the upper layer mining and the diffusion, analysis on the stability of interlayer rock in ascending mining with caving mining and pillar supporting mining .Then based on the structural theory, quantitative and feasible determination method is put forward about coal reserve of caving and pillar supporting mining, and through on-site trial , the scientific rationality and the objective application of the theory are proved.(4) Through on-site measurement, regularity of strata behavior by ascending mining of remaining coal reserve is explored. The results indicate that the process of ascending mining is influenced by exploitation of the lower coal seam, which causes the result that integrity of upper coal seal's wall rock weakens in different degrees. Before exploitation of the upper coal seam, self weight and load of overlying rock have been passed on to the rock mass outside the gob area functioning as pressure relief. Strata behavior by ascending mining of remaining coal reserve is not dramatic and periodic weighting length is short.Meanwhile, with the method of probability-integral, mobilization and deformation conditions of coal floor by ascending mining of remaining coal reserve is predicted and analyzed; comparision and contrast between the results from analysis and those from on-site measurement have been made; regularity of coal floor's mobilization and deformation by ascending mining of remaining coal reserve is explored.(5) Using combination with numerical simulation and theoretical analysis methods, analysis of the mechanical properties of the upper coal seam floor movement and deformation in ascending mining of coal reserve. On the basis, building the mechanical model of upper bottom plate rock layer migration in ascending mining concluding caving and pillar supporting mining. Through the mechanical solution method to obtain the forecast model.(6)Based theory, laboratory research and field measured studies, forming theory and technology of ascending mining in coal,carrying out tests and industrial implementation in the company of coal-fired electricity in Shanxi Coking Coal Xishan Coal Mine Group Baijiazhuang,sovling the technical problems about goaf recovery of the 6th coal seam under the 8th coal seam, achieved significant economic and environmental, social benefits. The technology in theory is a scientific and technically feasible. Residues up to the exploitation of mining area to the paper provide a theoretical guidance and technical support for ascending mining in coal reserve.
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