Experimental study on blasting characteristics of permafrost of Qinghai-Tibet Plateau

Tests on spherical and columnar explosive charges were carried out at one place of Qinghai-Tibet Plateau,Physico-mechanical properties of the permafrost were measured,and some blasting parameters were abtained.Then,some tests on deephole blasting were carried out on the permafrost.The abtained data were analyzed and studied,that is the optimal blasting parameters,the optimal scaled depth of charge,and the maximum scaled true volume.These data were compared with those acquired by Simpson,Simth and Morgonstern for permafrost.The shapes of rock explosive crater,permafrost explosive crater,and loess explosive crater,were compared and analyzed to find their difference.Relationship among those data and the physico-mechanical properties of permafrost were analyzed and studied,it was found that when the difference of temperature in permafrost was small,the blasting characteristic permafrost could not be expressed by one physico-mechanical property,and should be expressed by the combination of permafrost density,primary wave velocity,average grain size of permafrost,and total water content of permafrost,ρCW/D50.The larger the value of ρCW/D50,the more difficult to blast the permafrost.