| Rock directional fracture control blasting technology is widely applied in tunnels,rock lanes and slopes and other ground and underground blasting projects.It is a new technique of rock blasting based on explosive energy control and directional action.Among them,the slotted cartridge method is widely used because of its simple technical principle,convenient construction,and economic and practical use.However,for the weak rock masses,especially when weak structural planes such as joints and fissures are developed in the rock mass,it is difficult to obtain the ideal blasting effect with the blasting technology of the slotted cartridge.In order to overcome the deficiencies of the existing hard slotted cartridge blasting technology,this paper carried out related research on the flexible slotted cartridge blasting technology based on previous research.The research method combining theoretical analysis,experimental research,numerical simulation and field test reveals the blasting mechanism of flexible slitting cartridge,and applies the research results to the forming control of tunnel and roadway.The main research work is as follows:(1)With flexible soltted cartridge as the research object,the internal and external action mechanism of the slotted shell of the flexible slotted cartridge is deeply analyzed.The detonation process of explosives under the restraint of the flexible shell,the expansion and dispersion of the detonation products and the formation of the shaped jet process in the direction of the slot,Detonation products drives the flexible shell until it closely adheres to the wall of the blast hole to protect the rock mass in the non-slot direction.The formation mechanism and expansion characteristics of the initial directional crack and the main crack were systematically analyzed,and the gas submerged jet in a limited space was introduced to study the energy gathering effect of the flexible slotted cartridge(2)The main factors influencing the blasting effect of the flexible slitting cartridge are analyzed.Two factors affecting the slotted width and the radial uncoupling coefficient are selected for the flexible slotted cartridge explosion stress wave experiment.With the help of the super-dynamic strain test and analysis system,the pressure peaks of the flexible slot and the vertical slot were compared,and the influence of the slotted width and radial uncoupling coefficient on the distribution and propagation of the stress wave of the flexible slotted cartridge.(3)The blasting test and numerical simulation of the double-hole prefabricated micro-crack mortar specimen are used to compare and analyze the directional fracture effect of the three blasting methods: flexible slotted cartridge,hard PVC slotted cartridge and traditional cartridge,and different blasting methods for effects on prefabrication micro-crack propagation.At the same time,the wave velocity of the mortar specimen before and after blasting was measured with the aid of a rock mass ultrasonic detector,and the damage value of the flexible slit shell and hard PVC slot shell blasting method to the rock mass in all directions was quantitatively evaluated based on the change rate of longitudinal wave velocity.(4)Based on the experimental and simulation research results,the directional fracture controlled blasting technology of flexible slotted cartridges was applied to smooth blasting in roadways and tunnels with inclined layers.The field blasting test of flexible slotted cartridges and traditional cartridges showed that it was compared to traditional blasting method and the flexible slotted blasting method have obvious advantages in contour shaping control,reducing damage to the retained rock mass,controlling over-under-excavation and blasting in relatively broken rock mass,and have broad application prospects.This thesis includes 77 figures,31 tables,and 124 references. |
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