Research On The Controlled Blasting Method Under The Condition Of Decoupling Charge With Two Kinds Of Mediums

With the past theories and practices of fracture controlled blasting, on the basis of the present explosive theories and technology, combination the characteristic of hydraulic pressure blasting and gas decoupling blasting, the new method of fracture blasting was analyzed and applied using different coupling medium-water and gas within the hole at the same time.The charging construction uses the way of radial decouple charge. Air media and water media was separated by special pipe .Water media face the side of the blasting rock and air media face the side of the obligate wall rock.The theory of the blasting method is that water medium can transfer the energy of blasting fully while air medium pass energy of blasting in low efficiency. The charging construction can change the symmetrical state of blasting energy to control energy releasingand direction effectively, more control rupture direction, which makes it possible to destroy one side of the wall rock and at the same time protect the other side.The method includes the characteristic of hydraulic pressure blasting and gas decoupling blasting. The paper studies the cracking mechanism of directional broken control blasting by fracture mechanism. Using the broken damage theory, the paper also analyses the damage after blasting, establishes the reference of beginning, widening and ceasing of crack caused in the process of blasting, obtains their main parameters and formula.The paper studies the spreading of shock-wave and its effects in the hydraulic pressure blasting and air decoupling blasting in detail. It also introduce the causing of shock wave in the water and the gas, and its spread in blasting hole, as well as its reflection and transmission and effects of rock.We designed the special blasting pipe and carry through two spot experiments at Hong Wei mountain and Chen Jia Gou tunnel successfully. The section was trim and there were no crack on the surround rock. The effect can validate the feasibility of the theory.In brief, the new blasting method is an convenient and effective controlled fracture blasting method. It not only can controls the creating and extending of the cracking, but also can decreases vibration, protects rock stabilization, reduces powder and noise. It has great value of spreading usage.