Experimental Study On Hydraulic Blasting Lanping Jiayashan Open Pit

In open-pit mining, drilling method is widely used at present, and applied the most is deep hole blasting. In general, deep hole blasting has many advantages,such as, after blasting fragmentation, low rate of blasting chunk, secondary blasting greatly reduced; Blasting the negative effects are relatively small, greatly improved the safety of blasting, blasting field data also facilitate collection; Blasting construction process is simple, high mechanization degree, in addition to the need to set up cordon, evacuat the personnel and machinery in a short time, other time can use open stope point area wide at the same time the characteristics of parallel or overlapping between each process operations, make exceptionally rapid construction speed; Explosives with low cost, the cost of blasting is low and so on. But in fractured rock mass blasting, using deep hole blasting,there are more large size rocks at top and have root at the bottom of the hole, general mines in order to solve such problems will reduce the distance between the hole and shorten the length of hole filling and so on.But it may make hole total length increases a lot and making explosive dosage also increases a lot,then, Blasting cost becomes high and the surrounding environment is also damaged.In open stope of Lan Ping Jia Ya Mountain, when blasting in joint rock, there are many big rocks and root. However, if adjust the hole network parameters or increase explosive dosage as usual, this will lead to economic and environmental problems.To solve the problem in joint rock deep hole blasting in the open-pit mine which difficult problems mentioned above,this paper from the analysis on rock mass blasting theory, the basic principle of blasting damage of rock mass, the characteristics of joint rock blasting, the mechanism of water pressure blasting, deep hole hydraulic blasting charge structure and so on were studied. Using ANSYS/ls-dyna explicit nonlinear dynamic analysis software to simulate the water pressure blasting hole which the water bag at the bottom, middle, bottom and top, and at the same time simulate the conventional blasting. On the basis of theoretical analysis and numerical simulation, many different sets of the deep-hole water pressure blastingtests have been carried out in Lan Ping Jia Ya Mountian.(1) Deep-hole water pressure blasting can reduce the peak pressure of blast hole and quasi-static stress, prevent or greatly reduce the blasting crushed zone exists, greatly reducing the exercise in futility which explosives used on caused excessive broken rock. So The explosives energy is more fully utilized. (2) Based on micro compressibility of water, in the deep hole hydraulic blasting, the water have good role of energy transfer, transmit explosion energy to the surrounding rock uniform,no loss of,and rock fragmentation efficiency is greatly improved;(3) In joint rock blasting, the water in the hole of explosion temporary "sealed" role in the high pressure gas, avoid explosive raw gas leak from the crack too early, together with the density of water is much larger than the density of air, the frictional resistance in rock is greater than air. So, the presence of water, on the one hand, greatly extend the effect time that the pressure role on rock mass, on the other hand, in high pressure water is squeezed into the fissures,under the resistance, water applied to a great deal of pressure on the rock fracture surface, and concentrated stress is created in fractured ends. The pressure can make crack open, extension, and torn apart;(4) Through the ANSYS/ls-dyna software simulating, in four of deep-hole water pressure blasting charge structure, filled with water in the middle and both in bottom and upper of blasthole can obtain better blasting effect. Combined with field test results, the conclusion in the deep hole hydraulic blasting of joint rock mass is also established, it largely reduces the usage amount of explosives, highly improve the uniformity of blasting fragmentation, blasting, slungshot, noise and vibration are better controlled. But in terms of economy and operational aspects, filling water in the bottom and upper of the hole is more economically and affordable, only need to fill a explosive, the operation is simple and convenient.To sum up, the deep hole hydraulic blasting in Lan Ping Jia Ya Mountian joint rock blasting has obtained the good effect:the water make the filling length is shorter and make the explosive center of gravity become more high, improve the blasting quality of rock around the hole at the top; Filling water is shortened charging length and lossless transfer of explosion energy evenly to hole wall, and it make joint surface opening, tearing and bifurcation. Lan Ping Jia Ya Mountian open stope research practice shows that the deep hole hydraulic blasting is a kind of energy conservation and environmental protection, efficient new blasting method applied.