Study On Hole Stemming Theory Of One-step Deep Hole Raise Blasting And Its Application

One-step deep hole raise blasting technology is a safe, effective and low-cost way to solve raising difficulties. The main characteristics of this technology are to divide hole into several stratifications, filling appropriate stemming length and shaft-forming at a time by delay interval between layers. Stemming length is one of the most important parameters in one time deep hole raise blasting technology. A study is made to properly determine the hole stemming length and to improve the blasting effect of one time deep hole raise blasting, several conclusions can be obtained as follows:(1) According to rock fragmentation, material characteristics of hole stemming and elastic-plastic mechanics theory, the deformation calculation model of stemming under explosion load has been set up.(2) Based on the energy transfer in the process of deformation and movement and the relation between the time when the stemming moves out of the hole and the rock crushes, the stemming theory of one-step deep-hole blasting was been deduced from the kinetic energy theorem.(3) Through the approach of ANSYS/LS-DYNA3D nonlinear dynamic finite element software, process of cavity formation and propagation of the stress wave from one time deep hole raise blasting under different stemming length are analyzed. The distribution of element Misc. stress and node time-acceleration history curve are simulated. The results of numerical analysis provide some reference for improving the stemming theory of one time deep hole raise blasting.(4) Combined with engineering geological conditions of Sandaozhuang Mine, blast hole deviation and stratified situation, forming blasting scheme, achieve success in one time deep hole raise blasting test. And the correctness of stemming theory has been verified and provided some guidance for raise excavation by one time deep hole raise blasting technology.