Model Experimental Research Of Radon Measurement Applied In Monitoring For Overlying Stratum Fissure Of Shallow Coal Seam

Whether in China or in other countries ,Coal is one of the most important energy that provids most of the energy demand. With the rapid development of national economy, the demands for coal are getting more and more serious,So, Increasing exploitation of the coal resources are Main ways to easing the lack of Coal.But Large-scale coal mining , especially the shallow seam mining, is easy to Easy to cause surface subsidence or produce big fissure , cause groundwater erosion and surface damage to vegetation. If we can use some monitoring methods in coal mining process to master distribution of fissure in the overlying stratum,so can reduce the environmental destruction caused coal resources exploitation. Although currently there are many methods that used in detection of overburden rock breaking, but no one is a kind of very reassuring method characterized by effective and easy operation, and all can not be used to monitor the mining-induced fractures continuously.therefore,there will be the important practical significance ,if we can find a kind of both reliable and easy operation method.As is known to all, radon measurement technology has been a mature effective technology, it is applied widely to the geological field.we often use radon measurement technology to find concealed geological structures , oil and gas, groundwater and geothermal,uranium mine, coalfield depressed pillars ,burning area in the underground coal of coal field, map for geology, solve the relevant engineering geological problems etc,we have obtained good effect in practice;Meanwhile there are more the radon in coal seams than in the overlying stratums around the coal seams, In coal mining process,radon can move upward through the crack. These have created favorable conditions to monitor crack development and distribution of overlying stratum with the radon measurement techniques In coal mining process .But,in order to brought direct radon measurement technique relevance to fissure development in overlying stratum, there are many basic research work to do. Therefore, this paper rely on scientific research project"integrated experiment system development about detecting the mining-induced overlying stratums fractures and the hydraulic conductivity wit radon measurement technique",This project was developed with professor ZhangDongSheng who has worked in China mining university and professor FangFang who comes from chengdu university of technology. With domestic two shallow coal field as the prototype, use the solid and gas coupling model experiments to monitor radon migration situation before and after simulation of stoping, at the same time, with the help of gas migration rule in coal seam, established the mathematical model of the relationship between coal mining and the radon concentration of overlying stratum to provide experimental and theoretical basis For the development of monitoring system.This paper established three similar material simulation models in the experimental stage, the 1203 mining face of DaLiuTa Coal mine was the prototype of modelⅠ,it contained a key strata; the 32201 mining face of BuLianTa Coal mine was the prototype of modelⅡ, it contained two key stratas; except that water content ofweathered sandstone increased a lot in the upper part, the strata structures of modelⅢwre the same as modelⅡ.Based on measurement and analysis to the three similar material simulation models , Conclusions are as follows:(1 )the changes of radon concentration can better reflect fissure development situation of models in mining process.(2 )the changes of radon concentration are associated with the overlying stratum Structure in the model.(3 )it takes several hours from the development of fissures to the changes of radon concentration caused by fissures and captured by emanometer.Meanwhile, based on some problems appeared in previous experiments, this paper put forward several Suggestions for future problems:(1 )to enhance the stability of radon source system (2 ) to extend monitoring time of simulation experiment properly(3 ) to increase temperature and humidity sensor ,and stress sensor in the modelIn addition, all the experiment involved in the paper wre completed jointly by the author,Dr ZhangWei,and LiXiang master ,with the guidances of professor ZhangDongSheng and professor FangFang.