Coal bursts involve the sudden,violent ejection of coal or rock into the mine workings. They are almost always accompanied by a loud noise,like an explosion,and ground vibration. Bursts are a particular hazard for min...Coal bursts involve the sudden,violent ejection of coal or rock into the mine workings. They are almost always accompanied by a loud noise,like an explosion,and ground vibration. Bursts are a particular hazard for miners because they typically occur without warning. Despite decades of research,the sources and mechanics of these events are not well understood,and therefore they are difficult to predict and control. Experience has shown,however,that certain geologic and mining factors are associated with an increased likelihood of a coal burst. A coal burst risk assessment consists of evaluating the degree to which these risk factors are present,and then identifying appropriate control measures to mitigate the hazard. This paper summarizes the U.S. and international experience with coal bursts,and describes the known risk factors in detail. It includes a framework that can be used to guide the risk assessment process.展开更多
Full aero-elastic model tests are carried out to investigate wind-induced vibration of middle steel pylon of Taizhou Bridge. Model of the pylon under different construction periods is tested in both uniform and turbul...Full aero-elastic model tests are carried out to investigate wind-induced vibration of middle steel pylon of Taizhou Bridge. Model of the pylon under different construction periods is tested in both uniform and turbulent flow field. And the yaw angle of wind changes from transverse to longitudinal. Through full aero-elastic model testing, wind-induced vibration is checked, which includes vortex resonance, buffeting and galloping. Vortex resonance is observed and further studies are carried out by changing damping ratio. Based on wind tunnel testing results, wind-resistance of middle pylon is evaluated and some suggestions are given for middle pylon's construction.展开更多
文摘Coal bursts involve the sudden,violent ejection of coal or rock into the mine workings. They are almost always accompanied by a loud noise,like an explosion,and ground vibration. Bursts are a particular hazard for miners because they typically occur without warning. Despite decades of research,the sources and mechanics of these events are not well understood,and therefore they are difficult to predict and control. Experience has shown,however,that certain geologic and mining factors are associated with an increased likelihood of a coal burst. A coal burst risk assessment consists of evaluating the degree to which these risk factors are present,and then identifying appropriate control measures to mitigate the hazard. This paper summarizes the U.S. and international experience with coal bursts,and describes the known risk factors in detail. It includes a framework that can be used to guide the risk assessment process.
基金National Science and Technology Support Program of China(No.2009BAG15B01)National Science Foundation(No.51008233)
文摘Full aero-elastic model tests are carried out to investigate wind-induced vibration of middle steel pylon of Taizhou Bridge. Model of the pylon under different construction periods is tested in both uniform and turbulent flow field. And the yaw angle of wind changes from transverse to longitudinal. Through full aero-elastic model testing, wind-induced vibration is checked, which includes vortex resonance, buffeting and galloping. Vortex resonance is observed and further studies are carried out by changing damping ratio. Based on wind tunnel testing results, wind-resistance of middle pylon is evaluated and some suggestions are given for middle pylon's construction.
