Experimental Study On The Effect Of Pre-splitting Blasting Of Water Medium

The pre-splitting blasting technology plays an important role in the protection of the mine slope,the excavation of the electromechanical chamber and the construction of roads and Bridges.Then a lot of water blast hole often appear these engineering blasting due to natural precipitation,rock seepage and other factor,and the amount of water in each borehole varies greatly,which seriously affects the affect of pre-splitting blasting,and even serious damage to retained body.The main studying on the influence of the effect of presplitting blasting is analyzed from three aspects of the theoretical analysis of water and air medium,numerical simulation and similar model test.(1)A theoretical analysis of uncoupled charging blasting of air medium and water medium is based on the different physical properties of air and water,it is concluded that the propagation law of shock wave and high temperature and pressure explosion gas by explosion in the air medium and water medium,initial compressive stress of the hole wall,the quasi-static compressive stress of the hole wall and the crack propagation process in two different media.The same explosive is used to calculate the initial pressure of hole and quasi-static stress of two kinds of medium uncoupled charging blasting,it is resulted that the pressure of hole wall and quasi-static compressive stress produced by the uncoupled charging blasting of water are larger than that of air.(2)The numerical analysis model of five kinds of uncoupled charging blasting is established by using ANSYS/LS-DYNA nonlinear analysis software to analysis the stress of hole wall,effective stress,first and third principal stress of the center line of line under different water.In addition,the difference in the stress of the water and air in the mixed air and water are analyzed.It is obtained that the influence of different water content on the presplitting blasting effect.(3)The similarity model test was carried out.According to the geometric similarity principle to produce cement mortar specimen,and the designed water quantity is added into the test piece to test blasting.Which can analysis the influence of semi hole and roughness of the pre-splitting surface of different water of hole in the experiment of uncoupled charging blasting.After blasting,the cement mortar sample was carried out for coring,Then the sound wave of the processed specimen is tested,the rate of sound velocity reduction after the the blasting is analyzed,and thedamaged range of cement mortar around the hole is calculated.After the sound wave test,the compressive test is carried out on the specimen,in order to analyze the influence of presplitting blasting on the retention of rock strength.(4)Combined with numerical simulation and similar model test,the presplitting blasting experiment of different water flow industrial tests was carried out;After the experiment,the factors such as the ratio of half hole and the presplitting surface flatness was statistics and analysis.The test results show that the more water in hole,the less flatness of pre-splitting surface and the lower hole.