Experimental Research Of The Static Crushing In Medium-length Hole

The static fracture is a new blasting technology emerging in recent years, at present, this technology has been widely used. Compared with blasting, the static fracture is the important development and complement of traditional blasting technology with crushing process safety smoothly.Underground coal seam roof collapse is a problem encountered in the process of coal extraction, the generation of static crushing technology to solve this problem provides the possibility on theory and practice. Combined the medium-length holes roof processing with static fracture is a meaningful and practical study. There was no specific application of static fracture in roof processing at present, in this paper, broken rules of static fracture in the medium-length holes were studied through the method of combining the theoretical analysis and model test, aim to improve the effect of crushing, avoid the hidden danger of explosive blasting, confirmed the feasibility of the static fracture on mechanics theory.In this paper, I use chemical knowledge to describe the material transformation process in the disintegrating agent reaction, mechanical knowledge and theoretical formulas to analyze Static fracture mechanism in detail, and analyze the water cement ratio、time、ambient temperature、the size of the aperture、the depth、material properties and filling compactness such as the main factors of influence on static fracture briefly,which providing certain support on crushing test.From the six series of contrast test results through a deep hole steel pipe pressure test, we know that the actual tube maximum inflation pressure increases with the increase of pipe diameter while water cement ratio is equal, after punching, maximum pressure value can be measured in fracture agent hydration reaction at the bottom of the of steel tube, positively correlated with the size of the pipe diameter; When pipe diameter is equal, the maximum expansion pressure decreases with the increase of water cement ratio in a certain range but the construction is better. Reaction rate under the condition of the fracture agent with steel pipe constraint, conform to the speed regulation in free expansion hydration reaction of performance test roughly. By three groups of different specifications of the concrete model block broken process getting the following conclusions:taking level reserve hole (40mm,50mm) in concrete model test, charging process is more complicated than vertical aperture, cartridge type charging mode operation is relatively simple, deficiency of fracture agent compactness can lead to nozzle phenomenon in the process of hydration reaction; Compared to the smaller concrete block in size and reserved aperture in diameter, the reaction process of deep hole concrete test model is faster, and not began to appear crack propagation phenomenon in10～18hours after charging. Crack growth appears two main fracture crack along vertical symmetric in the section firstly instead of four fracture crack along axial symmetric or three main fracture crack symmetrical about center. After to the free surface, crack continues to expand in the direction of the charging, until the destruction, and in the event of a nozzle, appears a slight change. Static fracture agent volume and the broken concrete volume is not a simple multiple relationship, specific linear relation need further study.