Efficient cut blasting method for medium-length holes in deep high-stress rock roadway based on crustal stress induction effect

An efficient cut blasting method for medium-length holes in deep high-stress rock roadway, comprising:

• carrying out a crustal stress blasting test on the free face of the in-situ rock roadway to be excavated, and obtaining a distribution state of cracks under a synergistic action of crustal stress, explosion stress waves and clamping force of surrounding rock of a rock mass in the stratum where the in-situ rock roadway to be excavated is located;
• arranging a cutting hole net on the free face of the rock roadway to be excavated according to a distribution state of the cracks;
• performing cut blasting based on the cutting hole net;
• wherein, the step of carrying out a crustal stress blasting test on the free face of the in-situ rock roadway to be excavated, and obtaining the distribution state of cracks under the synergistic action of crustal stress, explosion stress waves and the clamping force of the surrounding rock of a rock mass in the stratum where the in-situ rock roadway to be excavated is located includes:
• drilling at least one test blast hole with the same depth as that of the cutting hole on the free face of the rock roadway to be excavated, and the diameter of the test blast hole is the same as that of the cutting hole;
• loading the same amount of explosives with the same charging method as that of the cutting hole in the test blast hole, and
• inserting a detonator and blocking the blast hole;
• detonating the detonator with an igniter and detonating the explosive through the detonator;
• after the explosion of explosives, the rock mass around the test blast hole is broken and cracks are formed, based on the synergistic action of the explosion stress waves, the deep crustal stress and the clamping force of the surrounding rock around the test blast hole;
• according to the visible cracks on the surface of the free face, determining the distribution state of the cracks on the rock mass section perpendicular to the axial direction of the blast hole;
• the rock mass section perpendicular to the axial direction of the blast hole contains a surface of the free face;
• the determining the distribution state of the cracks on the rock mass section perpendicular to the axial direction of the blast hole according to the visible cracks on the surface of the free face includes:
• taking the test blast hole as the center, determining the length of the crack extending around;
• using spray paint, marker pen or electronic scanner to connect the end points of the crack length to outline or draw the crack distribution profile on the surface of the free face to form the corresponding peripheral envelope of the cracks;
• wherein the arranging a cutting hole net on the free face of the rock roadway to be excavated according to the distribution state of the cracks includes:
• arranging the cutting hole net on the free face of the rock roadway to be excavated according to the shape and size of the peripheral envelope of the cracks;
• the shape of the peripheral envelope of the cracks is an ellipse, and the size of the peripheral envelope of the cracks is represented by its major axis and its minor axis;
• arranging the cutting hole net on the free face of the rock roadway to be excavated according to the shape and size of the peripheral envelope of the cracks includes:
• at least arranging a first group of cutting holes, and at least 4 cutting holes should be arranged in the first group, which are respectively the first cutting hole, the second cutting hole, the third cutting hole and the fourth cutting hole, wherein the hole diameter, hole depth, charging method and charging amount of the first cutting hole, the second cutting hole, the third cutting hole and the fourth cutting hole are the same as that of the test blast hole;
• according as the peripheral envelope of the cracks after the first cutting hole is detonated, and the peripheral envelope of the cracks after the second cutting hole and the third cutting hole are detonated respectively, have at least a tangent or intersecting part respectively, the peripheral envelope of the cracks after the second cutting hole is detonated and the peripheral envelope of the cracks after the third cutting hole is detonated have at least a tangent or intersecting part, and the peripheral envelope of the cracks after the fourth cutting hole is detonated and the peripheral envelope of the cracks after the second cutting hole and the third cutting hole are detonated respectively, have at least a tangent or intersecting part respectively, and the first cutting hole, the second cutting hole, the third cutting hole and the fourth cutting hole are arranged to form a first cutting area;
• the shape of the peripheral envelope of the cracks on the rock mass section upward along the axial direction of the blast hole and perpendicular to the axial direction of the blast hole is consistent;
• the determining the distribution state of the cracks on the rock mass section perpendicular to the axial direction of the blast hole according to the visible cracks on the surface of the free face further includes:
• determining the size of the peripheral envelope of the crack on the rock mass section upward along the axial direction of the blast hole and perpendicular to the axial direction of the blast hole;
• determining the three-dimensional distribution state of single-hole blasting cracks under the combined effect of crustal stress, explosion stress waves and clamping force of surrounding rock, according to the obtained shape and size of the peripheral envelope of the cracks on the rock mass section upward along the axial direction of the blast hole and perpendicular to the axial direction of the blast hole;
• the second cutting hole and the third cutting hole are respectively drilled obliquely to the center of the first cutting area. The center distance from the hole bottom of the second cutting hole to the hole bottom of the third cutting hole is less than or equal to the minor axis length of the peripheral envelope of the cracks at the hole bottom;
• the center distance from the hole bottom of the first cutting hole to the hole bottom of the fourth cutting hole is less than or equal to √{square root over (3)} times of the major axis length of the peripheral envelope of the cracks at the hole bottom.