Abstract:The results of theoretical studies and field tests on fracture plane control blast with notched boreholes have been introduced. In these studies, the single symmetrical notched borehole was simplified to a pressurized hole with two symmetrical cracks under the state of plane strain. In analyzing the growth and termination of the notch, only quasi-static pressure was considered. In the mean time, the rock to be blasted was considered to be isotropic. Based on the principles of fracture mechanics, the stress components near the tip of the notch were calculated, and the criteria for growth and termination of the notch were established. The growth direction of the notch was also predicted on the basis of strain energy density factor. An approach for estimating the amount of explosive for each hole and the spacing of holes was suggested. Furthermore, field  tests were conducted to check the results from the theoretical studies.

Key words: fracture plane control blast　notched borehole　fracture mechanics