According to the structure form of room and pillar goaf in gypsum mine, the mechanical model of pillar roof composite supporting structure was established in this research. Based on the cusp catastrophe theory and energy dissipation theory, the energy dissipation relationship of the support structure was analyzed, and a new instability criterion of the support system was derived by introducing the control parameters α and β. On this basis, the study of blasting caving was carried out. The influence of row spacing and hole depth on blasting caving was analyzed using ANSYS/LS DYNA software. The blasting influence range, stress wave attenuation and vibration velocity attenuation indices are obtained, and the blasting parameters such as the optimal distance and depth of blast holes between pillars and roof were optimized. Based on the results of theoretical analysis and numerical, combined with the engineering geological conditions of Dahan gypsum mine, the practical study of blasting caving was carried out. The caving scheme and caving sequence was determined, then the blasting caving effect was analyzed. The caving effect was found to be good, and the applicability of the theoretical model is verified.
The impacts of the enhanced model's moist physics and horizontal resolution upon the QPFs(quantitative precipitation forecasts)are investigated by applying the HIRLAM(high resolutionlimited area model)to the summer heavy-rain cases in China.The performance of the control run,for which a 0.5°×0.5°grid spacing and a traditional“grid-box supersaturation removal+Kuo typeconvective paramerization”are used as the moist physics,is compared with that of the sensitivityruns with an enhanced model's moist physics(Sundqvist scheme)and an increased horizontalresolution(0.25°×0.25°),respectively.The results show:(1)The enhanced moist physics scheme(Sundqvist scheme),by introducing the cloud watercontent as an additional prognostic variable and taking into account briefly of the microphysicsinvolved in the cloud-rain conversion,does bring improvements in the model's QPFs.Althoughthe deteriorated QPFs also occur occasionally,the improvements are found in the majority of thecases,indicating the great potential for the improvement of QPFs by enhancing the model's moistphysics.(2)By increasing the model's horizontal resolution from 0.5°×0.5°,which is already quitehigh compared with that of the conventional atmospheric soundings,to 0.25°×0.25°without thesimultaneous enhancement in model physics and objective analysis,the improvements in QPFs arevery limited.With higher resolution,although slight amelioration in locating the rainfall centersand in resolving some finer structures of precipitation pattern are made,the number of the mis-predicted fine structures in rainfall field increases with the enhanced model resolution as well. 相似文献