Research On Functional Mechanism And Application Of Control Hole Under Blasting Load

Blasting technology is widely used in national economic construction and resource exploitation, and the result of blasting is closely related to the design of blasting parameters.With the rapid development of coal industy,coal exploitation is facing serious challenges.Solving the problem encounted in production scientificaly is the foundation of safely and efficiency exploitation.The deephole blasting technology apply to solve the difficulty problem underground and control deep hazards. Control hole plays an important role in deephole blasting. It is extremely significant for improving the blasting effect.The model experiment is used for analysis the relationship of the distance between control hole and blasting hole to the blasting effect in this paper.In the experiment, the diameter of blasting hole and control hole are4mm and6mm, respectively. The mass of charge is1.0g, and the height of charge is about100mm. The distance between control hole and blasting hole is d.When d=3mm, control hole is located at crush zone. Under the action of explosion gas,the rock medium between the two holes was destory. The crack grew quickly and the explosion gas released from the control hole. The rock can not split due to energy of rock breaking was reduced. When d=6mm, control hole is located at crack zone. The stress concentrated and the value reach the fracture limit. The rock split along the line that joins the two holes. The control hole plays an important role in diractional fracturing. When d≥9mm, control hole is located at elastic zone. The rock split but not along the line that joins the two holes. The stress concentrated but not achieve the fracture limit. The rock split at random according to the damage crack distribute. From the experimental phenomenon,we may drew the conclusion that where the control hole located in the blasting acted zone is important for the rock split In hard rock roof weaken,there is not enough space to meet the demand of crack growth in view of the destory character of deep rock. In blasting design,the control hole is used for compensation the space that the rock medium in the blasting acted zone needed for replace.Take the deephole blasting in rock roof weaken for example,the paper state the application of deephole blasting in coalmine.There is no enough space for the crack growth underground. The control hole is used to provided enough space for the crack growth. It also plays an important role in directional splite. From the application of control hole in the hard roof weaken,the effect is apperantly. The load of workface support reduced greatly because the completeness of rock is decreased. The roof rock was altered from hard to weak.Control hole provided a way to solve the problem of engineering blasting in special conditions. The parameters of control hole is important for improving blasting result and increase the economic evenue.