By investigating the key survival and growth indexes, the results showed:（1）the stage of the seeding has the most important effective.The survival rate of the cuttings was the highest by using 1-year-old cuttings.Th...By investigating the key survival and growth indexes, the results showed:（1）the stage of the seeding has the most important effective.The survival rate of the cuttings was the highest by using 1-year-old cuttings.The older the cuttings,the lower the survival rate.（2）There was no obviously rules by using ABT.（3）By comparing the results of covering with black & white plastic velum and no covering,the white one is considered better than the two others.In practice work,the type of A1B1C2 was better.The concentration of ABT could be reduced,but the time of soaking should be prolonged.展开更多
Large cutting height fully mechanized top-coal caving is a new mining method that improves recovery ratio and single-pass production. It also allows safe and efficient mining. A rational cutting height is one key para...Large cutting height fully mechanized top-coal caving is a new mining method that improves recovery ratio and single-pass production. It also allows safe and efficient mining. A rational cutting height is one key parameter of this technique. Numerical simulation and a granular-media model experiment were used to analyze the effect of cutting height on the rock pressure of a fully mechanized top-coal caving work face. The recovery ratio was also studied. As the cutting height increases the top-coal thickness is reduced. Changing the ratio of cutting to drawing height intensifies the face pressure and the top-coal shattering. A maximum cutting height exists under a given set of conditions due to issues with surrounding rock-mass control. An increase in cutting height makes the top-coal cave better and the recovery ratio when drawing top-coal is then improved. A method of adjusting the face rock pressure is presented. Changing the cutting to drawing height ratio is the technique used to control face rock pressure. The recovery ratio when cutting coal exceeds that when caving top-coal so the face recovery ratio may be improved by over sizing the cutting height and increasing the top-coal drawing ratio. An optimum ratio of cutting to drawing height exists that maximizes the face recovery ratio. A rational cutting height is determined by comprehensively considering the surrounding rock-mass control and the recovery ratio. At the same time increasing the cutting height can improve single pass mining during fully mechanized top-coal caving.展开更多
文摘By investigating the key survival and growth indexes, the results showed:（1）the stage of the seeding has the most important effective.The survival rate of the cuttings was the highest by using 1-year-old cuttings.The older the cuttings,the lower the survival rate.（2）There was no obviously rules by using ABT.（3）By comparing the results of covering with black & white plastic velum and no covering,the white one is considered better than the two others.In practice work,the type of A1B1C2 was better.The concentration of ABT could be reduced,but the time of soaking should be prolonged.
基金Financial support for this work, provided by the National Basic Research Program of China (No.2007CB209400)the National Natural Science Foundation of China (No.51004104)
文摘Large cutting height fully mechanized top-coal caving is a new mining method that improves recovery ratio and single-pass production. It also allows safe and efficient mining. A rational cutting height is one key parameter of this technique. Numerical simulation and a granular-media model experiment were used to analyze the effect of cutting height on the rock pressure of a fully mechanized top-coal caving work face. The recovery ratio was also studied. As the cutting height increases the top-coal thickness is reduced. Changing the ratio of cutting to drawing height intensifies the face pressure and the top-coal shattering. A maximum cutting height exists under a given set of conditions due to issues with surrounding rock-mass control. An increase in cutting height makes the top-coal cave better and the recovery ratio when drawing top-coal is then improved. A method of adjusting the face rock pressure is presented. Changing the cutting to drawing height ratio is the technique used to control face rock pressure. The recovery ratio when cutting coal exceeds that when caving top-coal so the face recovery ratio may be improved by over sizing the cutting height and increasing the top-coal drawing ratio. An optimum ratio of cutting to drawing height exists that maximizes the face recovery ratio. A rational cutting height is determined by comprehensively considering the surrounding rock-mass control and the recovery ratio. At the same time increasing the cutting height can improve single pass mining during fully mechanized top-coal caving.
