The Formula of Calculating Charge for Blasting in Rock Mass by Dimensional Analysis

摘要

In the design of rock mass blasting engineering the specific charge is an important parameter for promoting blasting efficiency and meeting engineering demand. In practice the parameter changes in 0.3～0.8kg/m3 or more. In order to get the parameter engineers usually do small-scale test of crater blasting in site. In the paper a new dimensional table is given for finding di-menstonless variable. The failure mechanism is discussed about both crater blasting and loose blasting. It is suggested that specific charge is related to the strength of rock mass and the explosion energy and the shear strength and tensile strength of rock are introduced into formula for calculating charge in crater blasting and loose blasting respectively. Furthermore the strength of rock mass relates to the distribution of joints. A relationship between equivalent rock mass strength and the space of joints is given. By comparing with case history date a simple formula of calculating charge in crater and loose blasting in rock mass is given.