A reasonable unsupported roof distance(URD) when advancing underground coal mine roadways can contribute greatly to safe and rapid roadway development.A mechanical model of the roof,using the relationship between the ...A reasonable unsupported roof distance(URD) when advancing underground coal mine roadways can contribute greatly to safe and rapid roadway development.A mechanical model of the roof,using the relationship between the roof stress distribution and URD,obtained by the difference method,and roof stability according to the in-situ roof stress and rock mass strength was developed.We subsequently designed a proper range of URD,developed a testing method of URD with the function of mining protection,evaluated roof stability through analyzing the test data and then determined a reasonable URD.Considering the factors of the geological conditions,the immediate roof stability and the efficiency of the labor arrangement system,the URD of the advancing roadway of 9802 working face in Zhangshuanglou coal mine was determined to be 6 m using the proposed method.The results show that,when a 2 m length of roadway was reinforced by temporary support and high pre-stressed bolt support after the roadway advancement of 6 m per cycle,the speed and the security of the roadway development can be achieved and the advance rate can reach more than 400 m per month.展开更多
Improving the simulation accuracy of the advance distance based on the method of characteristics is essential to develop numerical solutions for simulating surface irrigation.Instead of volume balance in the tradition...Improving the simulation accuracy of the advance distance based on the method of characteristics is essential to develop numerical solutions for simulating surface irrigation.Instead of volume balance in the traditional method of characteristics(T-MC),the position of critical flow is determined to simulate the advance distance in the improved method of characteristics(I-MC),which is used in border irrigation systems with rapid variation in inflow discharge in the current research.Specifically,the zones of both subcritical and supercritical flow were firstly distinguished to determine the position of the critical flow point,which was also the upstream boundary of the wetting front region,and then the advance distance was calculated by applying the diffusive wave equation in the wetting front region.The results showed that the I-MC accurately simulated the advance distance with high determination coefficients(0.984-0.998)and low errors(root mean square error of 0.35-1.56 min and coefficient of residual mass of 0.01-0.06),which performed much better than the T-MC.The I-MC provided a suitable and simple numerical simulation tool to improve the establishment of numerical surface irrigation models.展开更多
基金supported by the State Key Laboratory of Coal Resources and Sate Mining,China University of Mining and Technology (No.SKLCRSM13X07)the National Natural Science Foundation of China (No.51174195)+1 种基金Chinese National Programs for Fundamental Research and Development (No.2013CB227900)the Fundamental Research Funds for the Central Universities (No.2014XT01)
文摘A reasonable unsupported roof distance(URD) when advancing underground coal mine roadways can contribute greatly to safe and rapid roadway development.A mechanical model of the roof,using the relationship between the roof stress distribution and URD,obtained by the difference method,and roof stability according to the in-situ roof stress and rock mass strength was developed.We subsequently designed a proper range of URD,developed a testing method of URD with the function of mining protection,evaluated roof stability through analyzing the test data and then determined a reasonable URD.Considering the factors of the geological conditions,the immediate roof stability and the efficiency of the labor arrangement system,the URD of the advancing roadway of 9802 working face in Zhangshuanglou coal mine was determined to be 6 m using the proposed method.The results show that,when a 2 m length of roadway was reinforced by temporary support and high pre-stressed bolt support after the roadway advancement of 6 m per cycle,the speed and the security of the roadway development can be achieved and the advance rate can reach more than 400 m per month.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51879073 and 51609064).
文摘Improving the simulation accuracy of the advance distance based on the method of characteristics is essential to develop numerical solutions for simulating surface irrigation.Instead of volume balance in the traditional method of characteristics(T-MC),the position of critical flow is determined to simulate the advance distance in the improved method of characteristics(I-MC),which is used in border irrigation systems with rapid variation in inflow discharge in the current research.Specifically,the zones of both subcritical and supercritical flow were firstly distinguished to determine the position of the critical flow point,which was also the upstream boundary of the wetting front region,and then the advance distance was calculated by applying the diffusive wave equation in the wetting front region.The results showed that the I-MC accurately simulated the advance distance with high determination coefficients(0.984-0.998)and low errors(root mean square error of 0.35-1.56 min and coefficient of residual mass of 0.01-0.06),which performed much better than the T-MC.The I-MC provided a suitable and simple numerical simulation tool to improve the establishment of numerical surface irrigation models.
