Study On Blasting Parameter Of Progressive Large Hole Spiral Cutting

Drilling and blasting method would still be the major method in roadway construction in a long term. There are mainly mid-section or narrow-bore tunnel in road construction of mine. Parallel cut is the main technological approach to improve cycle advance. Of which progressive large hole spiral cut with advances in less drill hole,less charging and well blasting effect. At present research on the blasting mechanism and method of determining parameter of it is seldom, just some simple application of engineering design.The essay analyze and research in detail of blasting parameter of the progressive large hole spiral cut from three aspects.Theoretical analysis of hole effect and mechanism of rock fracture in cut blasting. The effects of the hole are leading to stress concentration,acting as free surface and decompressing. And the breakage of rock is combined action of detonating gas,blast wave and stress wave.Theoretical analysis of determining parameter in cut blasting. Do systematical research on hole count,hole diameter, distance between hole and loaded hole,hole depth,explosive load and blasting delay time of progressive large hole spiral cut. Get distance between first load hole and hole under comparison through different computing method; propose graphical analysis according to minimum burden of other load hole; calculate burden and hole spacing and then draw hole placement diagram. Integrating with design formulas of explosive load per meter in normal blasting, design formulas of explosive load in small angle of rupture condition is quoted to dynamic analysis reasonable gunpowder charge line density. The time of rock blasting breaking is the lower limit of initiation delay time in cut blasting, initiation delay would be useless if initiation delay time is less then it. Integrate Livingston blasting crater theory and equivalent burden theory of column charge blasting, get design formulas of load hole depth quantitatively. Supply a detailed determining blasting parameter process for a actual engineering example.Recur cavity process in cut blasting with ANSYS/LS-DYNA 3D nonlinear dynamic finite element software. The load hole take the middle hole as burden to form blast crater firstly, and then take tunnel heading as another burden to larger blast crater. Through the process of forming blast crater, could intuitionally catch that rock near explosive was destroyed by compressing but rock surface was destroyed by stretching. The progressive large hole spiral cut's cavity formation process could be analyzed visualized through section printscreen.