| Rockburst and coal-gas outburst compound dynamic disaster is a complicated dynamical phenomenon which under interaction of rockburst and coal-gas outburst in deep mine.Compared with pure rockburst or coal-gas outburst,the mechanism of compound dynamic disaster is more complex,and its prediction and prevention becomes more difficult,thus brings more technological difficult problems to the safety mining of coal mine.Therefore,this paper carries on a study on the mechanism of compound dynamic disaster at first.On this basis,it presents the drilling multi-index monitoring method and makes a series of theoretical and experimental studies on it.The main contents and achievement of this paper are as follows:This paper has done statistical analysis on the exemplary cases of rockburst and coal-gas outburst compound dynamic disaster which happened in Pingdingshan Coal Mining Group,Fuxin mining area,Fushun Laohutai Mine,Longmei Coal Industry Group,Yangou Mine in Leping,Jiangxi,Xiayukou Mine in Hancheng,Shanxi,Xinyi Mine in Luoyang,Henan.Thus,the characteristics and the main influencing factors of rockburst and coal-gas outburst compound dynamic disaster are analyzed.It concludes that compound dynamic disaster has the characteristic of both rockburst and coal-gas outburst,it usually occurs in the areas which have complicated geological structure and deep excavation.When compound dynamic disaster strikes,secondary disasters such as gas explosion are easy to be induced.The main influencing factors of rockburst and coal-gas outburst compound dynamic disaster are coal rock stress,coal seam gas and coal rock property.In order to study the influence of gas pressure on the mechanical properties and rockburst tendency of coal rock,an uniaxial cmpression test of coal samples with no effective confining pressure is carried out.The test results show that the strength,elastic modulus and peak strain of coal rock all have a negative correlation with gas pressure.At the same time,the rockburst tendency of coal rock decreases with the increase of gas pressure.We also find that the effect of gas pressure on the mechanical properties and rockburst tendency gradually diminishes with the increase of gas pressure.According to the subject and form of energy release,the coal and gas dynamic disaster is classified into four types.They are rockburst,outburst induces rockburst type compound dynamic disaster,rockburst induces outburst type compound dynamic disaster and coal-gas outburst.The mathematical model of rockburst and coal-gas outburst compound dynamic disaster is established and its definite conditions are analyzed.Then compound dynamic disaster of circular roadway is analyzed analytically,and the mechanism of rockburst and coal-gas outburst compound dynamic disaster is analyzed on this basis.The monitoring principles of drilling bit temperature difference and drilling rod torque are analyzed,and the drilling multi-index monitoring method is established.In this method,indexes of drilling bit temperature difference,drilling rod torque and drilling cuttings weight are combined to monitor the risk of rockburst and coal-gas outburst compound dynamic disaster.Drilling multi-index monitoring device is independently developed and the drilling multi-index test system is established.The change regularities of drilling bit temperature difference and drilling rod torque are studied through experiment,and the experiment results are analyzed comparing with the drilling cuttings weight.The results show that,when other experimental conditions are the same,both drilling bit temperature difference and drilling rod torque increase with the increase of coal rock stress.On the whole,the maximum of drilling bit temperature difference,the changing rate of drilling bit temperature difference and the value of drilling rod torque grow with the increase of coal rock stress linearly.The change rules of drilling cuttings weight,drilling bit temperature difference and drilling rod torque have a good consistency.With the 8th Mine of Pingdingshan Coal Mining Group as the engineering background,the drilling multi-index prediction technique is applied to roadway and working face respectively.The distribution of distressed zone,stress concentration zone and original stress zone ahead of mining face is judged by testing drilling bit temperature difference and drilling rod torque during drilling process.The critical values of drilling bit temperature difference and drilling rod torque of the penta-9-10-12160 working face are initially determined through the regression analysis method of SPSS.The critical value of drilling bit temperature difference is determined as 33.0?,the critical value of drilling rod torque is determined as 37.0N·m. |
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