Study on rock mass failure characteristics of double-hole delayed blasting in interbedding based on particle expansion algorithm

The existence of the interface between soft and hard rock often makes it difficult to control blasting effect. Studying influence structural plane delayed initiation time on characteristics can make effect more controllable. In this paper, by using Particle Flow Code (PFC 2D ) particle expansion algorithm, double-hole experiments soft-hard are carried out, results analyzed from perspectives fragment gradation, micro contact force energy field. Results show that: 1) When in rock, if distance blasthole is about two times radius crushing area, will easier form large area fragments, fragments tend be crushed with increase distance. 2–4 delay time, overall value increases first then decreases, reaches maximum when 4 ms. 2) existing mass, become relatively uniform within a certain range. main direction appear uneven state generated simultaneous or initiation, which close parallel vertical connection. 3) greater than compared blasting, peak kinetic strain reduced 33% 46% respectively.