Blasting Damage Model And Numerical Test Of Rock Under Effect Of In Situ Stress

Drilling and blasting is still the most widely used method for rock breaking in mining engineering, underground traffic engineering, hydro-power engineering, etc. On the one hand the excavating rock need to be broken efficiently by blasting, but on the other hand blasting induced damage on surrounding rock should be controlled as far as possible to keep the stability of reserved rock. Besides, in-situ stress have a great impact on blasting process in deep underground blasting engineering. Therefore, damage modeling for rock blasting and its numerical testing on blasting induced damage evolution under different in-situ stress conditions is critical for recognizing blasting mechanism, promoting blasting effect and keep stability of existing rock mass. The study includes:(1) Based on damage mechanics theory, a mechanical model for rock blasting is established considering of the rock heterogeneity and in-situ stress field, in which rock blasting is considered as two consecutive stages, i.e. the dynamic stage caused by the stress wave and the static stage caused by explosion gas pressure. The blasting damage model is solved by Matlab programming with finite element software COMSOL Multiphysics, which provide a numerical tool for studying damage evolution induced by rock blasting.(2) Based on the blasting damage model, numerical test on single hole and double hole blasting under different in-situ stress conditions is conducted to study the impact of lateral pressure coefficient and depth on crack evolution. The guiding role of maximum stress direction on crack propagation is also discussed.(3) Numerical test on rock mass blasting with joint under different in-situ stress conditions is conducted to study the impact of ground stress and joint obliquity on crack evolution, especially the guiding role of joint obliquity on crack propagation.(4) Numerical test on cutting seam cartridge blasting under different in-situ stress conditions is conducted to study the guiding role of cutting seam on crack propagation. The impacting mechanism of lateral pressure coefficient, cutting seam angle, cutting seam thickness on directional controlled blasting is also discussed.(5) Based on numerical test on presplitting blasting for high-steep slope cutting project, the impact of charge parameter, priming sequences and hole layout on presplitting blasting and smooth blasting effect is studied to provide theoretical basis for slope blasting design.