Study On Similar Simulation Test Of Chute Controlled Blasting In Low Permeability Coal Seam

The technology of deep-hole pre-splitting controlled blasting can promote the expansion and increase of coal seam cracks,and thus accelerate the realization of gas penetration,so it is an effective means to prevent coal and gas outburst.The directional fracture controlled blasting can make the rock rupture in a specific direction,and the direction of crack is good,and the economic benefit is very obvious.At present,many scholars have done more research on the crack guidance of the control hole,but there is little research on the crack expansion of the trench-cut directional blasting.So this paper will compare and analyze the notched controlled blasting and the common controlled blasting through the laboratory similar simulation experiment and numerical simulation,and finally get the notched controlled blasting and the common controlled blasting.The strain and stress changes in the direction of the main crack and the direction of the non-main crack,and the damage state of the rock around the blasting hole under the two conditions of hole-making blasting provide the relevant theoretical basis for the technical parameters of the notched blasting.In this paper,the initial impact pressure of surrounding coal and rock mass and the damage zone of coal mass are calculated in the process of explosive explosion under two kinds of controlled blasting conditions which change the shape of blasting hole.The range of comminuted area and fracture area is calculated,and the related parameters of the groove joint are analyzed and expounded.The results of previous research are summarized and summarized,and the optimum groove joint parameters are obtained.After that,the proportioning of each part of roof,coal seam and floor is determined by the results of similar proportioning test,and the similar model test is designed.The fissure and super dynamic strain meter obtained from blasting test are designed.The controlled blasting model and the general controlled blasting model are simulated and calculated based on ANSYS/LS-DYNA.The direction of the control hole is analyzed by experiment and numerical simulation.The stress variation and crack propagation in the direction of 45°and perpendicular to the control hole are analyzed.The damage mechanism around the hole wall of the notched blasting is deeply analyzed.Based on similarity theory and similarity criterion,by adjusting the proportion of each part reasonably,four groups of different proportions are made for each part of the test piece.Then,the mechanical properties of 12 groups of proportioning test blocks were tested by YAW-300 microcomputer controlled electro-hydraulic servo pressure testing machine,and the material and the proportion of each part of the material were determined.The roof: sand: cement: gypsum: water = 5.8: 1.2: 05: 1.1.The coal seam is: sand: cement: gypsum: pulverized coal: water = 3.3: 0.4: 1.0: 1.8: 0.9.The bottom plate is: sand: cement: gypsum: water = 6.3: 0.9: 0.3:1.1.And finally,after the test block of the similar model is burst,the data acquisition system is adopted,the three groups of data are obtained by each group of experiments,the corresponding control hole direction,the 45-degree direction and the direction perpendicular to the control hole are respectively obtained,A stress concentration phenomenon occurs at the cut tip and a suppression region is present at the 45 deg.direction and a stress recovery state occurs in a direction perpendicular to the slot direction.The damage degree of the cut control blasting is mainly concentrated in the direction of the cutting groove,and the damage degree in other directions is less than that of the circular hole control blasting.Figure [46] table [13] reference [94].