| As a new method of coal mining,Underground Coal Gasification(UCG)has been massively and multidimensionally researched by lots of countries,however UCG has not been unable to realize introduction production so far.One of the reasons why UCG is ineffective is that the location and range of combustion zone of underground coal gasification couldn’t be judged validly,which,however,is the premise of effective control of the UCG.Based on the corpus "Integrated detection technology of UCG working face" subordinate to the major research project------national "863" plan "key technology of industrialization of underground coal gasification",the paper applied method of radioactive radon measurement to monitor working face of underground coal gasification combustion zone.It is a long period that applyment of radioactive radon measurement to monitor working face of underground coal gasification combustion zone,however many factors have inevitable negative influences on monitoring radon during this period,such as periodic chance of seasons,rain,snow,medium and so on.In order to take the edge off impact of the factors,the studies of the distribution law of radon under influence of different factors are necessary.The paper studied the distribution regularity of radon concentration under the condition of different depth within two mediums-soil and basalt in Ulanchap,then carried on the analysis researches of the impact of radon concentration change relative with depth under the condition of different seasons and various external factors(humidity,atmospheric pressure,temperature,ground temperature).Research shows that:160cm is nodal point of radon concentration change in soil region,regularity of radon concentration changed with depth is various before and after nodal point,full seasons and three external factors-humidity,atmospheric pressure,temperature have different influences on radon concentration changed with depth before and after nodal point;40cm and 60cm both are nodal points in basalt region.In order to obtain the distribution law of radon concentration of Ulanchap field background,It took long term to monitor radon within 40cm depth in the testing site whose medium blended with soil and basalt.Simultaneously,radon concentration in different weather conditions and external factors(humidity,temperature,ground temperature,atmospheric pressure)were studied.The conclusion is that:in sunny days,the crucial factors which influenced radon concentration are air temperature and ground temperature;in rainy and snowy days,humidity has pivotal impact on radon concentration.Emendation formulas of radon concentration in the condition of various weather conditions and the application scope of the formulas are achieved.Based on all the studies above,the paper compared the distribution law of radon concentration in the medium of unique soil or unique basalt with that in the medium of blended soil and basalt under the same weather condition,then the distribution law of radon concentration in the medium of unique soil or unique basalt were corrected to that in the medium of blended soil of basalt.After the analysis,it is concluded that medium correction coefficient K in soil,basalt and mixture(blended with soil and basalt)is 0.62,1,1.01,respectively,moreover error analysis of correction factors are discussed,finally comprehensive correction formulas of different meteorological condition under the condition of different mediums are put forward.It is through the comprehensive correction formulas that monitoring radon concentration in the process of underground coal gasification and combustion condition in various weather conditions and different mediums,which makes field radon background at the same level in all conditions.Using such analysis methods which have ability to truly isolated radon anomalies produced by underground coal gasification and combustion provided a solid foundation for radioactive radon measurement method of monitoring underground coal gasification and combustion. |
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