Advanced Materials Research Vols. 524-527

Abstract: The Jin-tan underground energy storage of salt rock in Jiangsu Province as a demonstration project, Established a similar model experimental platform of concentration filed in construction period of salt caverns, which based on the similar theory of dimensional analysis. To analysis the concentration distribution and the concentration field variation in cavity. The study shows that: the brine concentration in the same horizontal plane is uniformly distributed beyond the boundary layer where has a higher concentration than other locations, but a continuous gradient distribution of brine concentration increases with depth in the vertical direction. In the vertical direction, the brine concentration gradient firstly increases and then decreases with the increase of the freshwater flow in the reverse circulation method. And in the vertical direction, the brine concentration gradient also firstly increases and then decreases with the increase of the distance between the two wash pipes in the reverse circulation method. Comparing with the reverse circulation method, the brine concentration gradient in the vertical direction is very insignificant with direct circulation. During the solution of mining of the salt cavity, the brine concentration increases as time goes on, and the rate of increase continues to decrease until the concentration field to stabilize.

Abstract: The ground subsidence and deformations caused by underground mining not only affect people’s life tremendously, but also ruin the local eco-environment. These phenomenons (disasters) should be controlled and rehabilitated. For this purpose, in this paper, the characteristic and values of surface subsidence, deformation and movements were evaluated and calculated using some kinds of technological theories and methodology such as probability integral method and so on. Based on the Google Earth image and digital relief maps as well as the predicted results and data, several types of 3D thematic maps of mining subsidence and deformation were designed and mapped in order to carry on the land reclamation or rehabilitation in the mining subsidence and deformation areas. The research results can be fitted well with the reality of surface subsidence and deformations.

Abstract: In view of open-pit mine complex special terrain, to improved method of constructing triangulated irregular net and combined with the extended boundary, that can remission the phenomenon that steps were flattened and the problem of inefficiency mining area model update. Using constrained triangulated irregular net once generation algorithm, through extraction of spatial data, establish topological relationships and spatial indexing, eventually build a constraints of triangulated irregular net within the boundary constraint line. Combining extended boundary with the triangulated irregular net generated algorithm, can realize the establishment partial model as well as partial and overall model splicing. Thus enhanced the efficiency of the mining area overall model updating.

Abstract: The risk evaluation index system of tailings pond is established on the basis of the characteristics of tailings pond and the requirements of laws in China.To make up for the deficiencies of the present index weight determined methods and many risk assessment methods, this article presents a risk assessment methodology based on the Fuzzy Sets Theory, which is an effective tool to deal with subjective judgement.The proposed methodology incorporates knowledge and experience acquired from many experts. The weight of the indexes are considered two risk factors: risk probability, risk impact. Triangular fuzzy theory as the mathematical background is used in the paper to solve the problem of subjectivity and uncertainty to determine index weights and index values. The proposed method is applied to assess a certain tailings pond in Benxi. The most notable differences with other fuzzy risk assessment methods are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation. The result indicates that this method used is feasible and rational. The work specified in this paper can be as reference to the evaluation work of the tailings pond in China.

Abstract: Surface subsidence has some peculiarities for the mining of the Han jia wan coal mine. Based on the surface movement observation of 2304 working face in Han jia wan coal mine, mining strata movement parameters are analyzed, the main factors which influence the formation of surface cracks in the gob are proposed and the failure mechanism of surface movement and deformation are studied for the mining of shallow coal seam and thick loose bed. Correlative parameters are presented and scientific basis is established for the coal mining under buildings, rail and water and the leaving of the safety pillar in the future.

Abstract: Using theoretical analysis and actually test research to analyze stress condition of filling body and average subsidence of the key strata, analysis shows that the average vertical stress in filling body was about 15Mpa when entering into stable state, which is equal to the primary stress, 13.75Mpa. The filling body could tighten the roof well and the filling body can support full weight of the overlying strata. The limestone, thickness of 5.3m, above the 81006 working face is the key strata of mining stope. On the interaction between ground pressure and the supporting force of filling body, the whole key strata subsided about 98.64mm on average theoretically, as the height meter monitored, the subsidence value of key strata was 108mm on average, conforms to the theoretical value, which proves the filling effect was good. At the early stage after filling, the roof subsided relatively faster as the filling body had not coagulated completely and the strength was lower. At this stage the roof was not tightened enough with the filling body, it subsided relatively faster in some certain limited space. After a while, the limestone, the key strata of mining stope, became stable for a short term, and then it would continue to subside until being stable under the disturbance of the high layer, because the movement of lower layer created some space for high layer.

Abstract: In order to make a comprehensive and accurate prediction of surface movement and deformation in the thin coal seams mining under buildings, mathematical model of the selection of rock movement parameter is established by the way of artificial neural network; ground surface movement and deformation is predicted and analyzed through probability integral method, mining scheme of the thin coal seams mining under buildings in a coal mine is determined.

Abstract: By defining and studying the time series of gas emission concentration (which was called G series in the paper), weighted moving average (WMA) model for pre-warning of coal and gas outburst was developed. The long & short-term trend curved lines of G series were drawn with the data of “3.30” coal and gas outburst of a coal mine. The results indicate, at normal production periods, coal body containing gas kept relatively steady, the gas content curved line, and long & short-term trend curved lines all changed mildly. Before occurring of outburst, some abnormal variations were found, including roadway body broken, gas energy released obvious increase or fluctuation of gas emission concentration, the gas content curved line passing through moving average curved line, long-term and short-term trend curved lines breaking through each other. The result of this study can be selected as the precursors to pre-warning coal and gas outburst.

Abstract: Mine ventilation is one of the most fundamental measures preventing gas accumulation. Through analyzing the advantages and disadvantages of Y-type ventilation, the paper proposed and practiced Y+L ventilation after relevant study and investigation when traditional Y-type ventilation only could not solve the gas problem on workface of Hexi Mine, i.e. to adopt the technique of maintaining airway along roadway, arranging airway as the return airway on work face, and to dig the transportation roadway of the next work face n advance as the tail roadway of 3303 work face, so as to jointly form the Y+L ventilation pattern of the mining face. This method is applied to the gas control of 3303 work face.

Abstract: The technology of mining without coal pillar is popular in many mine, though it can improve the recovery rate, it aggravate the air leakage of gob. Because of the ignorance about oxidation in gob, so it is very difficult to know the true value. When we make the test, we find computer can do it that simulation is consistent with reality overall. The article simulate the velocity field and oxygen concentration by finite element method, so divide the ‘three zones’ of gob and analysis the differences before and after plugging, we can see the huge impact of air leakage. So if we want to prevent the Spontaneous Combustion in mining without coal pillar, it is necessary to use the plugging technology.