Borehole Blasting With Water-couple Charge And Its Application In Tunnel Engineering

The traditional blasting for tunnels uses pure clay to stem the blast-holes. The efficient energy availability of explosive is not high and the specific explosive consumption is large. With the rapid development of economy, how to reduce the amount of explosive and blast effectively have become the urgent problem. In view of this condition, this paper puts forward a method of water-clay composite blasting for tunneling. It substitutes water-clay composite for pure clay to stem the blast-holes, called water-couple charge borehole blasting . Using the incompressible property of water and the stemming role of clay, this method reduces the decay of shockwave in the process of spread and relatively extends the functioning time of blasting air. So the water-clay composite blasting method improves the breakage of rocks and the efficient energy consumption of the explosive. In conjunction its successful application in Beiling Mountain tunnel, the mechanism and charge structure of water-couple borehole blasting is performed through from theory study, experiment project and numerical simulation.The spreading of shock wave and its effects in the hydraulic pressure blasting and air decoupling blasting are studied in detail. It compared with shock pressure and quasi-static stress in the air and water. It also introduce the causing of shock wave in the water and air, and its spread in blast-hole. Strain test, stress test and charge structure model test are performed under different stemming, and found better charge structure through comparative analyzing test results. Calculation principle of explicit dynamic finite element program LS-DYNA is studied. Through the software of LS-DYNA970, indoor strain test and single hole charge blasting process under different stemming are simulated, the distribution character of effective stress in rock by blasting is studied, simulation results are compared, which verify the theory and promote the application of computer simulation in rock blasting. In Beiling Mounatin tunnel advancing, it lowered the dirt volume and saved explosives usedBy mechanism study and successful application in site, the better charge structure of borehole water-couple blasting is concluded as follows: the length of water-column in the bottom of borehole is 18～22cm; the length of water-colum in the middle of borehole is 20～100cm, the length proportion of water-column to stemming is 0.75～1.