A method for preparing rock structural plane based on two-dimensional blasting
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING ZHONGKUANG INNOVATION ALLIANCE ENERGY & ENVIRONMENTAL SCI RES INST
- Filing Date
- 2026-06-05
- Publication Date
- 2026-07-03
Smart Images
Figure CN122329792A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of geotechnical engineering specimen preparation technology, and more specifically, to a method for preparing rock structural surfaces based on two-dimensional blasting. Background Technology
[0002] The natural structural surfaces of rocks have a significant impact on the mechanical properties of rock masses and are the core research object in related fields. However, natural structural test specimens are difficult to obtain and are easily damaged. Therefore, artificial preparation of rock specimen substrates with structural surfaces has become the main research approach.
[0003] Existing methods for preparing rock samples, such as cutting, splitting, pre-embedding, molding, and 3D printing, have several shortcomings: cutting and thin-slab extraction methods can easily alter the mineral composition of the rock or cause local damage; splitting is not suitable for large-scale model preparation; molding and 3D printing methods are not only costly to design and limited by material properties, but also produce specimens with mechanical properties that deviate significantly from real rock. Furthermore, the preparation results of molding and thin-slab extraction methods are highly dependent on the precision of the mold and the skill of the operator, making them difficult to implement in practice. They cannot accurately orient and form continuous structural surfaces, avoid disorder or excessive fragmentation of the rock, and completely preserve the original structure and mechanical properties of the real rock, making it difficult to meet the stringent requirements of indoor gneiss structural surface rock mechanics tests.
[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0005] This disclosure provides a method for preparing rock structural surfaces based on two-dimensional blasting, which can accurately and directionally form continuous structural surfaces, avoid disorder or excessive fragmentation of rocks, and completely preserve the original structure and mechanical properties of real rocks, thus meeting the requirements of indoor structural surface rock mechanics tests.
[0006] According to one aspect of this disclosure, a method for preparing rock structure surfaces based on two-dimensional blasting is provided, characterized by comprising the following steps: Provide rock specimen substrates; Determine the foliation orientation of the rock specimen substrate; The drilling area and drilling direction are determined based on the foliation orientation of the rock specimen substrate. Drill holes in the defined drilling direction within the drilling area to obtain mounting holes; Prepare a blasting device, the blasting device including a shaped charge tube and an expanding agent disposed inside the shaped charge tube, the tube wall of the shaped charge tube is provided with two shaped charge zones arranged opposite each other in the radial direction, the shaped charge zones are provided with a plurality of shaped charge holes arranged at intervals along the axial direction of the shaped charge tube, and the outer diameter of the shaped charge tube matches the inner diameter of the mounting hole. Place the blasting device into the mounting hole; The blasting device is detonated to obtain the blasted substrate, which is then used as the target specimen.
[0007] In an exemplary embodiment of this disclosure, determining the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate includes: selecting the drilling area on the surface of the rock specimen substrate parallel to the foliation direction, wherein the drilling direction is perpendicular to the foliation direction.
[0008] In one exemplary embodiment of this disclosure, selecting a drilling region on the surface of a rock specimen substrate parallel to the foliation direction includes: the geometric center of the drilling region being located at the center of the surface.
[0009] In one exemplary embodiment of this disclosure, the diameter of the drilled area is larger than the diameter of the mounting hole, and the axis of the mounting hole coincides with the geometric center of the drilled area.
[0010] In an exemplary embodiment of this disclosure, after determining the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate, and before drilling a hole in the drilling area along the determined drilling direction to obtain the mounting hole, the method for preparing a rock structure surface based on two-dimensional blasting further includes: The drilled area of the rock specimen substrate is pretreated, the pretreatment including grinding the surface of the drilled area and cleaning the rock specimen substrate; The pretreated rock specimen substrate is dried to a preset moisture content range.
[0011] In one exemplary embodiment of this disclosure, drilling a hole in the drilling area along a defined drilling direction to obtain a mounting hole includes: The rock specimen substrate is fixed to the drilling table, and a flexible buffer structure is provided between the drilling table and the rock specimen substrate to reduce the damage to the rock specimen substrate caused by vibration during subsequent drilling. The drilling direction is calibrated using a positioning and calibration structure, and the hole position of the mounting hole is marked to ensure that after the blasting device is placed into the mounting hole, the energy-concentrating zone corresponds to the preset cracking direction of the rock specimen substrate. Drilling is performed in the drilling area, and the hole depth error is kept within a preset range.
[0012] In one exemplary embodiment of this disclosure, the step of calibrating the drilling direction using a positioning calibration structure and marking the position of the mounting hole to ensure that the energy-concentrating zone corresponds to the preset cracking direction of the rock specimen substrate after the blasting device is placed in the mounting hole includes: A laser level is set up and a laser beam is emitted to determine the relative position of the rock specimen substrate and the laser beam. The angle of the drilling table is adjusted according to the relative position so that the side of the rock specimen substrate is parallel to the laser beam. Move the rock specimen substrate so that the laser beam is projected perpendicularly at the geometric center of the borehole area; Adjust the position of the drilling machine and the angle of the drill bit so that the extension direction of the drill bit coincides with the laser beam.
[0013] In one exemplary embodiment of this disclosure, drilling in the drilling area and keeping the hole depth error within a preset range includes: Drilling at the first preset feed rate; Stop drilling after reaching the first preset depth and remove debris from the hole; Repeat the above steps until the drilling depth is less than the target depth by a second preset depth. Then reduce the feed rate to the second preset feed rate and continue drilling to the target depth.
[0014] In one exemplary embodiment of this disclosure, the step of detonating the blasting device includes using an image acquisition device to simultaneously record the crack propagation morphology of the rock specimen substrate during the blasting process.
[0015] In one exemplary embodiment of this disclosure, the preparation of the blasting device includes a shaped charge tube and an expanding agent disposed within the shaped charge tube. The wall of the shaped charge tube is provided with two shaped charge zones arranged radially opposite to each other. The shaped charge zones are provided with a plurality of shaped charge holes spaced apart along the axial direction of the shaped charge tube. Matching the outer diameter of the shaped charge tube with the inner diameter of the mounting hole includes fabricating the shaped charge tube by 3D printing.
[0016] The method for preparing rock structural surfaces based on two-dimensional blasting disclosed herein first determines the foliation orientation of the rock specimen substrate, and then plans the drilling area and drilling direction according to the foliation orientation. This ensures that the subsequent blasting energy can be released along the natural weak surface of the rock or in a predetermined direction, avoiding random rock fragmentation and laying the foundation for the directional formation of the structural surface. In the blasting device subsequently prepared, two shaped charge zones radially opposite to each other on the wall of the shaped charge tube and shaped charge holes arranged axially at intervals enable the energy released after the expansion agent is detonated to be concentrated in the predetermined direction, forming two symmetrical directional splitting stress bands. This causes the rock to split along the symmetrical plane. At the same time, the matching design of the outer diameter of the shaped charge tube and the inner diameter of the mounting hole ensures that the blasting energy is uniformly transmitted close to the hole wall, avoiding excessive fragmentation caused by local stress concentration. Finally, the substrate after blasting forms a target specimen with a continuous structural surface. Moreover, the rock specimen substrate is based on real rock, and the structural surface is formed by the rock itself splitting without being disturbed by mechanical cutting or other means. This method can completely preserve the original mineral composition, particle structure, and mechanical properties of the rock, meeting the needs of indoor structural surface rock mechanics tests.
[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description
[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.
[0019] Figure 1 This is a flowchart of a method for preparing rock structure surfaces based on two-dimensional blasting according to an embodiment of this disclosure; Figure 2 This is a schematic diagram of drilling holes along a defined drilling direction within a drilling area to obtain mounting holes, as shown in one embodiment of this disclosure. Figure 3 This is a schematic diagram of a focusing tube in one embodiment of the present disclosure; Figure 4 for Figure 3 Sectional view at point AA; Figure 5 This is a schematic diagram of a blasting device according to an embodiment of the present disclosure; Figure 6 This is a schematic diagram of placing the blasting device into the mounting hole in one embodiment of the present disclosure; Figure 7 This is a schematic diagram of sealing the blasting device in the mounting hole in one embodiment of the present disclosure; Figure 8This is a flowchart illustrating the process before drilling holes are installed, after determining the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate in one embodiment of this disclosure. Figure 9 This is a flowchart illustrating drilling along a defined drilling direction within a drilling area, as described in one embodiment of this disclosure. Figure 10 This is a flowchart illustrating the use of a positioning and calibration structure to calibrate the drilling direction and mark the position of the mounting hole in one embodiment of this disclosure; Figure 11 This is a flowchart illustrating drilling in a drilling area and keeping the hole depth error within a preset range, according to one embodiment of this disclosure.
[0020] Explanation of reference numerals in the attached figures: 1-Rock specimen substrate; 11-Mounting holes; 2-Explosive device; 21-Charging tube; 211-Charging zone; 212-Charging hole; 22-Expanding agent; 23-Fuse; 24a-Positive lead; 24b-Negative lead; 25-Coupled medium; 26-Detonator; 3-Sealing materials. Detailed Implementation
[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.
[0022] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples in the accompanying drawings. It is understood that if the device of the icon is flipped so that it is upside down, the component described as "upper" will become the component described as "lower." When a structure is "upper" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.
[0023] As mentioned in the background section, traditional blasting relies on the instantaneous release of energy by the blasting device to break the rock mass. The energy diffuses randomly, making it difficult to precisely control the direction of action. In order to solve the above problems, this disclosure provides a rock shaping and cutting method based on high-energy gas sequential fracturing, which can achieve precise fracturing of the rock mass to be fractured along a human-preset direction to form geometrically regular and highly intact blocks.
[0024] The following will describe specific embodiments and appendices. Figure 1-11 The technical solution of the method for preparing rock structural surfaces based on two-dimensional blasting in this application is further explained.
[0025] like Figure 1 As shown, the method for preparing rock structure surfaces based on two-dimensional blasting in this disclosure includes the following steps: S1 provides a rock specimen substrate.
[0026] Original rock blocks that meet the experimental requirements are selected and provided as the processing object. For example, the substrate needs to have a certain degree of integrity, homogeneity and suitable physical and mechanical properties so that structural surfaces can be formed by directional blasting. The lithology of the rock specimen substrate 1 can be selected according to the research needs. For example, in this embodiment, it can be gneiss. Gneiss has a typical foliation structure and natural weak surfaces inside. It can be well adapted to the subsequent directional drilling and shaped charge blasting splitting operation based on the foliation direction. Therefore, it is a more suitable substrate type for preparing rock structural surface rock specimen substrate 1.
[0027] S2, determine the foliation direction of the rock specimen substrate.
[0028] Among them, foliation orientation refers to the spatial extension direction of the foliated structure inside the rock. Foliation is a common structural feature in metamorphic rocks such as gneiss. It is manifested as the oriented parallel arrangement of platy and columnar minerals inside the rock under geological processes, thus forming a series of approximately parallel natural weak surfaces. Foliation orientation reflects the overall extension direction of these weak surfaces. Therefore, by determining the foliation orientation of the rock specimen substrate 1, the extension direction and distribution characteristics of the natural weak surfaces inside the rock can be clarified, providing a basis for the subsequent rational planning of drilling location, drilling direction and shaped charge blasting direction, ensuring that the structural surface formed after blasting matches the natural structure of the rock, and avoiding disordered fragmentation of the rock specimen substrate 1. In this embodiment, the foliation orientation can be determined directly by visually observing the surface texture, mineral grain arrangement direction and layered distribution characteristics of the rock specimen substrate 1, or it can be determined by combining simple markings.
[0029] S3. Determine the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate.
[0030] After clarifying the orientation of the foliation, it is necessary to combine the extension direction of the natural weak surface of the rock to reasonably select the area for drilling on the rock specimen substrate 1 (i.e., the drilling area), and at the same time determine the spatial extension direction of the drilling (i.e., the drilling direction) so that the drilling direction and the foliation orientation are compatible. In this way, by coordinating and matching the drilling area with the drilling direction and the foliation orientation, it is possible to ensure that the energy generated by subsequent blasting is effectively transferred and released along the natural weak surface of the rock, prompting the rock to regularly split along the predetermined direction to form structural surfaces. This avoids problems such as disordered fragmentation of the rock specimen substrate 1 and distortion of structural surface morphology due to unreasonable drilling arrangement, and provides clear position and direction guidance for subsequent drilling and blasting operations.
[0031] S4, Drill holes in the drilling area along the determined drilling direction to obtain mounting holes 11.
[0032] like Figure 2 As shown, a channel for placing the blasting device 2 is machined into the rock specimen substrate 1 by mechanical drilling. The drilling process is carried out strictly according to the preset position and direction to ensure accurate hole positioning and regular hole shape, and to ensure that the size of the resulting mounting hole 11 is adapted to the subsequent blasting device 2. The mounting hole 11 formed by this step provides a stable installation space for blasting components such as the shaped charge tube 21, and also ensures that the energy during blasting can be concentrated in the rock interior along the predetermined direction, providing a reliable structural foundation for the subsequent directional splitting to form a structural surface.
[0033] S5, Prepare a blasting device. The blasting device includes a shaped charge tube and an expanding agent disposed inside the shaped charge tube. The tube wall of the shaped charge tube has two shaped charge zones arranged radially opposite to each other. Multiple shaped charge holes are opened on the shaped charge zones and spaced apart along the axial direction of the shaped charge tube. The outer diameter of the shaped charge tube matches the inner diameter of the mounting hole 11.
[0034] like Figures 3 to 5 As shown, the expanding agent 22 in the blasting device 2 of this disclosure can generate explosive gas after being activated. Part of the explosive gas can be ejected through the focusing hole 212 and impact the rock borehole wall corresponding to the focusing hole 212 to generate initial damage. Another part of the explosive gas can act on the pipe wall of the non-focusing zone of the focusing tube 21, so that the pipe wall in this area expands radially and applies expansion pressure to the corresponding rock borehole wall to form tensile stress concentration at the initial damage site. Radial initial tensile cracks are formed at the tensile stress concentration site. The explosive gas rushes into the initial tensile cracks to form a directional fracture surface on the rock borehole wall.
[0035] The matching of the outer diameter of the focusing tube 21 with the inner diameter of the mounting hole 11 ensures that the focusing tube 21 can be smoothly installed into the mounting hole 11 and fit against the hole wall. Furthermore, the axial multi-focusing hole 212 and the two-dimensional symmetrical focusing design ensure that the energy is evenly distributed along the hole depth. The focusing tube 21 can be made of polyvinyl chloride polymer material with flame retardant material through printing, so that the focusing tube 21 has a certain strength and toughness and can withstand large deformations without breaking. This avoids the interference of fragments generated by the breaking of the focusing tube 21 on the cutting of the rock mass, ensures the regularity of the rock block formation, avoids the rock block damage caused by fragments hindering the expansion of cracks, and ensures that the explosive gas acts in a preset direction, effectively guiding the rock mass to crack along the artificially set path, avoiding excessive fragmentation or disordered cracks, thereby ensuring the integrity of the structural surface.
[0036] The expanding agent 22 in the blasting device 2 is the core component for triggering blasting and releasing energy. In one embodiment provided in this disclosure, the expanding agent 22 is located in the middle position inside the blasting device 2. In this embodiment, the expanding agent 22 can be composed of a reducing agent (30%-65%), an oxidizing agent (30%-40%), an additive (5%-30%), a binder (1.25%), and a catalyst (0.5%-3%). After being triggered, it can release a large amount of explosive gas instantaneously, providing an energy basis for directional rock blasting. Moreover, after the expanding agent 22 is triggered, it will not generate a detonation wave. Only the high-temperature gas does work on the expansion of the rock mass, which can avoid the instantaneous uncontrolled diffusion of energy and damage to the borehole wall, resulting in better directional fracture effect.
[0037] like Figure 5 As shown, the blasting device 2 may also include a fuse 23, a fuse wire, and a coupling medium 25. The components work together to complete the detonation and energy transfer. The specific structure and function are as follows: The expanding agent 22 has a built-in fuse 23, which is used to trigger the reaction of the expanding agent 22. Its positive and negative terminals are connected to positive lead 24a and negative lead 24b, respectively. The other ends of positive lead 24a and negative lead 24b are connected to the detonator 26. The main functions are to transmit current and trigger the fuse 23 to act, thereby causing the expanding agent 22 to release energy.
[0038] To achieve the fixation, sealing and energy transfer of the expanding agent 22, a coupling medium 25 is provided at both ends inside the blasting device 2. The coupling medium 25 can be solid, gas or liquid. In this embodiment, sand particles are used as an example. It can not only fix and seal the expanding agent 22, but also help transfer the blasting energy released after the expanding agent 22 is ignited, so as to ensure that the energy acts directionally on the rock mass.
[0039] The fuse 23 can be an electric heating element such as an electric heating wire or an electric heating plate that can generate heat when energized. For example, the fuse 23 can be a copper sheet. When the lead wire is connected to the current, the temperature of the copper sheet will rise, which will then trigger the expansion agent 22.
[0040] S6, Place the blasting device into the mounting hole 11.
[0041] Specifically, such as Figure 6 and Figure 7 As shown, after the blasting device 2 is placed into the mounting hole 11, the mounting hole 11 is sealed with sealing material 3, so that the blasting device 2 is confined within the mounting hole 11. At the same time, the opening of the mounting hole 11 is sealed. In this embodiment, chemical adhesive can be used to seal the hole to ensure that the seal is tight and firm, thereby preventing the explosive gas generated by the explosion from rapidly leaking out of the hole, avoiding energy loss, increasing the explosion pressure in the hole, prolonging the action time of the explosion pressure on the rock specimen substrate 1, and allowing the crack to fully expand.
[0042] S7, detonate the blasting device to obtain the blasted substrate, and use the blasted substrate as the target specimen.
[0043] In this embodiment, detonation can be achieved by electric detonation. Specifically, current is provided by an external detonator 26. The current is transmitted through the positive lead 24a and the negative lead 24b to the fuse 23 built into the expanding agent 22. The fuse 23 is an electric heating element such as an electric heating wire or an electric heating plate. After being energized, it heats up rapidly and generates heat, which then ignites the expanding agent 22, causing it to react and release a large amount of explosive gas instantaneously. The energy of the explosive gas is transferred to the focusing tube 21, and then acts directionally on the rock borehole wall through the focusing zone 211 and the focusing hole 212, causing the rock to split directionally along the preset direction and foliation direction, and finally obtaining a specimen with structural surfaces, i.e., the target specimen.
[0044] The method for preparing rock structural surfaces based on two-dimensional blasting disclosed herein first determines the foliation orientation of the rock specimen substrate 1, and then plans the drilling area and drilling direction according to the foliation orientation to ensure that the subsequent blasting energy can be released along the natural weak surface of the rock or in a predetermined direction, avoiding random rock fragmentation and laying the foundation for the directional formation of the structural surface; subsequently, in the blasting device 2, the two radially opposite energy-concentrating zones 211 of the energy-concentrating tube 21 and the axially spaced energy-concentrating holes 212 can concentrate the energy released after the expansion agent 22 is detonated onto the predetermined direction, forming two... The symmetrical directional splitting stress zone causes the rock to split along the symmetrical plane. At the same time, the matching design of the outer diameter of the energy-concentrating tube 21 and the inner diameter of the mounting hole 11 ensures that the blasting energy is uniformly transmitted close to the hole wall, avoiding excessive fragmentation caused by local stress concentration. Ultimately, the substrate after blasting forms a target specimen with a continuous structural surface. Moreover, the rock specimen substrate 1 is based on real rock, and the structural surface is formed by the splitting of the rock itself without being disturbed by mechanical cutting or other means. It can completely preserve the original mineral composition, particle structure and mechanical properties of the rock, meeting the requirements of indoor structural surface rock mechanics test.
[0045] In one exemplary embodiment of this disclosure, determining the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate includes: selecting a drilling area on the surface of the rock specimen substrate 1 parallel to the foliation direction, wherein the drilling direction is perpendicular to the foliation direction.
[0046] Drilling holes parallel to the foliation direction allows the borehole axis to be aligned with the foliation plane, facilitating the uniform transmission of blasting energy along the dominant fracture direction of the rock. This avoids disordered rock fragmentation caused by boreholes deviating from the foliation surface. Furthermore, drilling holes perpendicular to the foliation direction allows the energy-concentrating zones 211 on the energy-concentrating tube 21 to be directly aligned with the foliation extension direction. This enables the high-pressure gas and splitting force generated after the expansion agent 22 is detonated to act directly on the weak foliation surface, pushing the rock to split neatly along the foliation direction. This reduces the energy required for cracking and effectively controls the orientation and shape of the structural surface, ensuring that the structural surface is straight, continuous, and has uniform roughness.
[0047] In one exemplary embodiment of this disclosure, selecting a drilling region on the surface of a rock specimen substrate parallel to the foliation direction includes: the geometric center of the drilling region being located at the center of the surface of the rock specimen substrate.
[0048] The geometric center of the drilling area is set at the center of the surface of the rock specimen substrate 1, so that the drilling is arranged at the center. This ensures that the splitting force acts symmetrically on the rock matrix, causing the rock to crack symmetrically along the predetermined foliation direction. The resulting structural surface is centered and regular in shape, and the rock specimen substrate 1 is subjected to uniform stress and has better integrity.
[0049] In one exemplary embodiment of this disclosure, the diameter of the drilled area is larger than the diameter of the mounting hole 11, and the axis of the mounting hole 11 coincides with the geometric center of the drilled area.
[0050] Setting the diameter of the drilling area to be larger than that of the mounting hole 11, while aligning the axis of the mounting hole 11 with the geometric center of the drilling area, provides reasonable tolerance for actual drilling operations while ensuring the precise positioning of the mounting hole 11. This reduces the risk of the hole deviating from the preset center due to minor deviations during drilling, improving construction convenience and product qualification rate. Furthermore, the concentric arrangement of the mounting hole 11 and the drilling area ensures that the subsequently inserted shaped charge tube 21 is always at the symmetrical center of the rock specimen substrate 1, allowing the blasting energy to be transmitted evenly and symmetrically to the surrounding hole wall. This avoids problems such as uneven stress distribution, severe local breakage, or skewed structural surfaces caused by eccentricity, thereby forming a straight, continuous, and centrally located structural surface. This ensures that the rock specimen substrate 1 is subjected to symmetrical forces and has a regular shape, thus improving the stability and accuracy of the rock mechanics test results of the structural surface.
[0051] In one exemplary embodiment of this disclosure, such as Figure 8 As shown, after determining the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate, and before drilling holes along the determined drilling direction within the drilling area to obtain the mounting hole 11, the method for preparing the rock structure surface based on two-dimensional blasting further includes: S31, Pre-treatment of the drilled area of the rock specimen substrate, including grinding. The pre-treatment mainly includes grinding the surface of the drilled area and cleaning the rock specimen substrate.
[0052] Grinding removes loose debris, protruding edges, rough undulations, and weathered layers from the surface of the drilling area, making the surface smooth and uniform. This provides a stable contact surface for the drill bit during subsequent drilling, reducing drill bit deviation, jamming, or edge chipping at the hole opening, and ensuring the positional accuracy and verticality of the mounting hole 11. On the other hand, it also allows the blasting device 2 to fit snugly against the rock hole wall surface, preventing unevenness of the rock hole wall from affecting the centered placement of the blasting device 2.
[0053] After grinding, the rock specimen substrate 1 is cleaned to remove stone powder, dust and other impurities generated during grinding. This prevents dust from entering the subsequently formed mounting holes 11 and clogging the energy-concentrating holes 212, thus affecting the transmission of blasting energy. At the same time, it keeps the rock specimen substrate 1 clean overall, avoiding the interference of impurities on the formation process of the structural surface and the mechanical properties of the rock specimen substrate 1.
[0054] Specifically, if the grinding area is too small, the weathered layer on the surface of the rock specimen substrate 1 will not be completely removed. During drilling, the drill bit is prone to slippage and deflection due to the uneven surface, resulting in hole position deviation and hole axis tilt. At the same time, chipping and breakage of the hole opening are likely to occur. It will also lead to uneven energy transfer and disordered stress distribution during subsequent blasting or loading. If the grinding area is too large, it will excessively cut the surface material of the rock specimen substrate 1, expand the damage range of the surface of the rock specimen substrate 1, introduce additional microcracks, destroy the structural integrity of the rock specimen substrate 1, change its original mechanical state, and thus interfere with the results of subsequent mechanical tests, affecting the accuracy and reliability of the test data. Therefore, in this embodiment, the diameter of the grinding area can be determined to be 3-5 times the diameter of the subsequent drilling hole to avoid the adverse effects caused by the grinding area being too small or too large.
[0055] S32, dry the pretreated rock specimen substrate to a preset moisture content range.
[0056] After cleaning, residual moisture remains on the surface and in the internal pores of the rock specimen substrate. If subsequent drilling and blasting operations are carried out directly, the moisture will change the local mechanical properties of the rock and may generate additional gas pressure due to instantaneous vaporization at high temperature during blasting. This could lead to uncontrollable rock cracking direction, rough and disordered structural surfaces, or even excessive fragmentation of the rock specimen substrate 1. In this embodiment, by drying the rock specimen substrate 1 to the preset moisture content range for the test, for example, by rinsing it with clean water and then drying it in a ventilated place until the moisture content is less than 0.5%, the interference of moisture on the rock strength, deformation characteristics, and blasting response can be eliminated. This ensures that the rock specimen substrate 1 is in a stable state and meets the indoor test standards. It ensures that the blasting process is controlled only by the energy-concentrating device and the foliated structure to control the splitting morphology, avoiding test errors caused by moisture content fluctuations. Furthermore, a suitable and uniform moisture content can prevent secondary cracks from occurring in the rock due to uneven drying and wetting, ensuring the integrity of the rock specimen substrate 1 matrix. This results in stable mechanical properties of the final prepared structural rock specimen substrate 1, reliable and repeatable test results.
[0057] In one exemplary embodiment of this disclosure, such as Figure 9 As shown, drilling a hole along a defined drilling direction within the drilling area to obtain the mounting hole 11 includes: S41, the rock specimen substrate is fixed to the drilling table, and a flexible buffer structure is set between the drilling table and the rock specimen substrate to reduce the damage to the rock specimen substrate caused by vibration during subsequent drilling.
[0058] Adding a flexible buffer structure between the rock and the workbench can effectively absorb and attenuate the vibration and impact generated during drilling, avoid direct transmission of vibration through rigid contact, thereby reducing problems such as microcracks, edge chipping, and surface damage in the rock specimen substrate, and maximizing the integrity and original mechanical properties of the rock specimen substrate 1.
[0059] The flexible buffer structure can be made of materials with certain elasticity and damping, such as rubber pads, silicone pads, cork pads, felt pads or polyurethane buffer pads. These materials are soft and stable under pressure, which can not only achieve buffering and vibration reduction, but also will not cause indentation or damage to the surface of the rock specimen substrate 1 during the fixing process.
[0060] S42, the drilling direction is calibrated by the positioning and calibration structure and the hole position of the mounting hole 11 is marked to ensure that after the blasting device is placed into the mounting hole 11, the energy-concentrating zone corresponds to the preset cracking direction of the rock specimen substrate.
[0061] This ensures that the subsequent drilling angle and hole center are consistent with the initial design, thereby guaranteeing that after the blasting device 2 is placed in the installation hole 11, the focusing zone 211 on the focusing tube 21 can be accurately aligned with the preset cracking direction of the rock specimen substrate 1. Calibration and marking through the positioning calibration structure can prevent misalignment of the focusing zone 211 with the preset cracking direction due to drilling direction deviation or hole position offset, thus preventing problems such as disordered cracking, skewed structural surfaces, or breakage of the rock specimen substrate 1 after blasting. Simultaneously, this operation allows the energy of the focused blast to be concentrated on the foliated weak surface and the predetermined path, ensuring that the formed structural surface is straight, continuous, and directionally controllable, so that the final rock specimen substrate 1 meets the requirements of indoor mechanical testing for the morphology and positional accuracy of the structural surface.
[0062] In this embodiment, the positioning calibration structure can be any form of positioning calibration structure, such as a laser level, a high-precision right-angle ruler, a plumb bob and plumb line, a digital inclinometer, an optical theodolite, or a total station. Those skilled in the art can choose according to actual needs, and there are no limitations here.
[0063] S43, Drill holes in the drilling area and keep the hole depth error within the preset range.
[0064] After the rock specimen substrate 1 is fixed, oriented, and marked with holes, actual drilling is performed on the rock specimen substrate 1. The purpose is to form installation holes 11 with precise dimensions and positions and orientations that meet the design requirements, for subsequent placement of the blasting device 2. The hole depth error is controlled within a preset range to ensure that the shaped charge tube 21 is properly positioned after being inserted into the hole. This prevents the blasting device 2 from being exposed due to shallow holes, causing energy leakage or unsafe blasting, and also prevents the shaped charge zone 211 from deviating from the preset cracking area due to excessive hole depth. This ensures that the blasting energy acts uniformly along the height direction of the rock specimen substrate 1, resulting in a structural surface with appropriate depth and complete shape.
[0065] In one exemplary embodiment of this disclosure, such as Figure 10 As shown, a positioning and calibration structure is used to calibrate the drilling direction and mark the position of the mounting hole 11 to ensure that after the blasting device is placed into the mounting hole 11, the energy-concentrating zone corresponds to the preset cracking direction of the rock specimen substrate, including: S421, Set up a laser level and emit a laser beam to determine the relative position of the rock specimen substrate and the laser beam. Adjust the angle of the drilling table according to the relative position so that the side of the rock specimen substrate is parallel to the laser beam.
[0066] In this embodiment, a straight and stable laser beam emitted by a laser level is used as a high-precision reference to replace traditional visual positioning or simple measuring tools. This allows for a direct and accurate determination of the placement of the rock specimen substrate 1. By adjusting the angle of the worktable to make the side of the rock specimen substrate 1 parallel to the laser beam, it is ensured that the rock specimen substrate 1 is in a straight and uniform installation posture. This ensures that the subsequent drilling direction is perpendicular to the foliation direction and does not deviate, providing a reliable geometric reference for hole position calibration and precise drilling. It also avoids drilling angle deviations caused by the skewed placement of the rock specimen substrate 1, thereby ensuring that the energy-concentrating zone 211 accurately corresponds to the preset cracking direction.
[0067] Specifically, turn on the laser level and mount it on a stable tripod, ensuring the instrument surface is parallel to the ground. Adjust the tripod height to position the laser level at a suitable working height. Adjust the laser level to project a vertically downward laser beam onto an empty area of the worktable. Slowly move the worktable, bringing the rock specimen substrate 1 close to the vertical laser beam until the distance between them is less than 1 cm. Use a vernier caliper with a graduation of 0.02 mm to measure the distance from the laser beam to two different positions on the upper and lower sides of the rock specimen substrate 1. If the difference in distance between the two positions is ≤0.02 mm, it indicates that the side of the rock specimen substrate 1 is parallel to the vertical laser beam. If the difference is greater than 0.02 mm, fine-tune the angle of the worktable and repeat the above steps until the requirements are met.
[0068] S422, Move the rock specimen substrate so that the laser beam is projected perpendicularly onto the geometric center of the borehole area.
[0069] Specifically, move the position of the rock specimen substrate 1 so that the laser beam is projected onto the center point of the upper surface of the rock specimen substrate 1. Then, use a vernier caliper with an accuracy of 0.02 mm to measure the distance between the center point and the edge of the rock specimen substrate 1. Repeat the measurement 3 times and take the average value to ensure that the deviation of the hole center position is ≤0.5 mm. If it does not meet the requirements, readjust the worktable and repeat the above steps until the requirements are met. Mark the drilling center on the surface of the rock specimen substrate 1 with a marker pen, and lock the worktable and the rock specimen substrate 1.
[0070] S423, adjust the position of the drilling machine and the angle of the drill bit so that the extension direction of the drill bit coincides with the laser beam.
[0071] Specifically, the position and angle of the drilling machine are adjusted so that it is completely aligned with the laser beam, and then the drilling machine spindle is locked.
[0072] In one exemplary embodiment of this disclosure, such as Figure 11 As shown, drilling is performed in the drilling area, and the hole depth error is kept within a preset range, including: S431, Drilling according to the first preset feed rate.
[0073] S432, stop drilling after reaching the first preset depth and remove debris from the hole.
[0074] S433, repeat the above steps until the drilling depth is less than the target depth by a second preset depth, then reduce the feed rate to the second preset feed rate and continue drilling to the target depth.
[0075] Specifically, for example, the first preset feed rate is controlled at 0.1-0.2 mm / s to avoid edge chipping and drill bit wear caused by high-speed feed; during drilling, the drilling status is observed in real time, and drilling is paused every 10 mm (first preset depth) to remove debris from the hole and prevent debris accumulation from affecting drilling accuracy; when the drilling is 10 mm away from the target depth (second preset depth), the feed rate is reduced to 0.05 mm / s (second preset feed rate), and drilling is slowly continued until the target depth is reached. Then, the drilling machine is turned off, and the spindle is allowed to rest. After the drill bit has completely stopped rotating, slowly withdraw it from the hole to prevent it from scratching the hole wall. After drilling is completed, use a depth micrometer to check the actual hole depth. When measuring, insert the micrometer vertically into the bottom of the hole to ensure that it is completely in contact with the bottom of the hole. Repeat the measurement multiple times and calculate the average value to ensure that the error between the actual hole depth and the target hole depth is less than ±0.5mm (the hole depth error is within the preset range). If the actual hole depth is too small, the drilling machine needs to be restarted and the feed depth needs to be finely adjusted until the requirements are met. If the actual hole depth is too large, the rock specimen substrate 1 is scrapped.
[0076] In one exemplary embodiment of this disclosure, the step of detonating the blasting device includes using an image acquisition device to simultaneously record the crack propagation morphology of the rock specimen substrate during the blasting process.
[0077] Specifically, the rock specimen substrate 1 is placed in the visualization blasting test platform. Its overall frame is welded from a 10mm thick carbon steel structure, with dimensions of 1100mm×1100mm×800mm. Visual windows are provided on its front, right, and top sides. The material is ultra-white tempered glass with a thickness of 10mm, which has both transparency and protection functions.
[0078] After the operator has evacuated to a safe area, the detonator is used to trigger the detonation, and the high-speed camera is used to record the crack propagation process. After the detonation, the sample is left to stand for 10 minutes until the rock specimen substrate 1 is stable before entering the site to observe the formation state of the structural surface.
[0079] Simultaneously with the detonation of the blasting device 2, an image acquisition device is used to record the crack propagation morphology of the rock specimen substrate 1 under the blasting action. This allows for direct observation and data storage of the rock cracking process. In this embodiment, high-speed photography and high-definition video recording are used to capture the entire process from the release of blasting energy and the initial crack formation to the extension, penetration, and eventual formation of the structural surface along the foliation direction. On the one hand, this allows for direct verification of whether the blasting direction and energy focusing effect are consistent with the design, and judgment of whether the cracks propagate orderly along the preset path, providing a direct basis for process optimization and parameter adjustment. On the other hand, it allows for the quantification and archiving of crack propagation trajectory, propagation speed, and fracture morphology, facilitating subsequent analysis of the structural surface formation mechanism. It also provides real and traceable image data for indoor rock mechanics tests and blasting effect evaluation, improving the accuracy of research results.
[0080] In one exemplary embodiment of this disclosure, the preparation of a blasting device includes a shaped charge tube and an expanding agent disposed inside the shaped charge tube. The wall of the shaped charge tube is provided with two shaped charge zones arranged radially opposite to each other. Multiple shaped charge holes are provided on the shaped charge zones and spaced apart along the axial direction of the shaped charge tube. The outer diameter of the shaped charge tube matches the inner diameter of the mounting hole 11. The shaped charge tube 21 is fabricated by 3D printing.
[0081] Using 3D printing to fabricate the shaped charge tube 21 significantly improves the processing accuracy and structural symmetry of the component, ensuring precise uniformity in the position, spacing, and diameter of the shaped charge holes 212 on both sides, thereby allowing the explosive energy to be released uniformly and stably along the predetermined direction. Simultaneously, 3D printing allows for the rapid customization of shaped charge tubes 21 to different specifications according to experimental needs, eliminating the need for additional molds, thus shortening the processing cycle and reducing the cost of small-batch trial production. Furthermore, the shaped charge tubes 21 produced by this process exhibit greater consistency, effectively ensuring uniformity of experimental conditions across multiple sets of rock specimen substrates 1, reducing experimental errors caused by component differences, and thereby improving the stability of the preparation of the rock structural surface rock specimen substrate 1 and the reliability of the experimental results.
[0082] Specifically, in this embodiment, a 3D printing system is used to print and prepare the shaped charge tube 21. The printing material is a standard photosensitive resin material. The shaped charge tube 21 is a cylinder with a length of 100mm, an outer diameter of 11mm, an inner diameter of 9mm, and a wall thickness of 1mm. There is a row of circular shaped charge holes 212 at symmetrical positions on both sides of the device. The diameter of the shaped charge holes 212 is 2mm and the hole spacing is 3mm. An expanding agent 22 is filled into the shaped charge tube 21. When the amount of explosive reaches 2 / 3 of the volume of the shaped charge tube 21, a current initiating device is placed in the shaped charge tube 21 and fixed in the gap of the expanding agent 22. Then the remaining expanding agent 22 is filled in to complete the production of the blasting device 2.
[0083] The rock structural surface preparation method based on two-dimensional blasting disclosed herein can efficiently replicate the characteristics of real structural surfaces. The cracks generated by blasting have natural randomness and irregularity in shape, which can restore the roughness, continuity, and branching crack characteristics of natural structural surfaces. The concentrated stress generated by two-dimensional blasting causes structural surfaces to be generated in the weak points of the rock specimen substrate 1. This "through-weak surface" characteristic makes the roughness coefficient and undulation angle of the joint surface closer to the real rock mass, which is more in line with the characteristics of natural structural surfaces than mechanical cutting and artificial design.
[0084] Furthermore, the blasting method is highly efficient and can complete the preparation of multiple sets of rock specimen substrates 1 in a short time. Its efficiency is far higher than mechanical processing methods such as cutting, and the preparation cost is extremely low. It is especially suitable for scientific research experiments that require the preparation of a large number of specimens with structural surfaces.
[0085] In addition, the preparation of target specimens with structural surfaces using two-dimensional blasting technology is simple, requires no complex and precise operations, and is no longer limited by mold precision or material constraints, making it adaptable to complex working conditions and engineering scenarios.
[0086] It should be noted that although the steps of the method for preparing rock structure surfaces based on two-dimensional blasting in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that these steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.
[0087] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.
Claims
1. A method for preparing rock discontinuity based on two-dimensional blasting, characterized in that, Includes the following steps: Provide rock specimen substrates; Determine the foliation orientation of the rock specimen substrate; The drilling area and drilling direction are determined based on the foliation orientation of the rock specimen substrate. Drill holes in the defined drilling direction within the drilling area to obtain mounting holes; Prepare a blasting device, the blasting device including a shaped charge tube and an expanding agent disposed inside the shaped charge tube, the tube wall of the shaped charge tube is provided with two shaped charge zones arranged opposite each other in the radial direction, the shaped charge zones are provided with a plurality of shaped charge holes arranged at intervals along the axial direction of the shaped charge tube, and the outer diameter of the shaped charge tube matches the inner diameter of the mounting hole. Place the blasting device into the mounting hole; The blasting device is detonated to obtain the blasted substrate, which is then used as the target specimen.
2. The method of claim 1, wherein the method further comprises: The step of determining the drilling area and drilling direction based on the foliation direction of the rock specimen substrate includes: selecting the drilling area on the surface of the rock specimen substrate parallel to the foliation direction, wherein the drilling direction is perpendicular to the foliation direction.
3. The method of claim 2, wherein the method further comprises: The selection of a drilling region on the surface of the rock specimen substrate parallel to the foliation direction includes: the geometric center of the drilling region being located at the center of the surface.
4. The method for preparing rock discontinuity based on two-dimensional blasting according to claim 3, characterized in that, The diameter of the drilled area is larger than the diameter of the mounting hole, and the axis of the mounting hole coincides with the geometric center of the drilled area.
5. The method of claim 1, wherein the method further comprises: After determining the drilling area and drilling direction based on the foliation orientation of the rock specimen substrate, and before drilling holes along the determined drilling direction within the drilling area to obtain mounting holes, the method for preparing rock structural surfaces based on two-dimensional blasting further includes: The drilled area of the rock specimen substrate is pretreated, the pretreatment including grinding the surface of the drilled area and cleaning the rock specimen substrate; The pretreated rock specimen substrate is dried to a preset moisture content range.
6. The method of claim 1, wherein the method further comprises: The step of drilling holes along a defined drilling direction within the drilling area to obtain mounting holes includes: The rock specimen substrate is fixed to the drilling table, and a flexible buffer structure is provided between the drilling table and the rock specimen substrate to reduce the damage to the rock specimen substrate caused by vibration during subsequent drilling. The drilling direction is calibrated using a positioning and calibration structure, and the hole position of the mounting hole is marked to ensure that after the blasting device is placed into the mounting hole, the energy-concentrating zone corresponds to the preset cracking direction of the rock specimen substrate. Drilling is performed in the drilling area, and the hole depth error is kept within a preset range.
7. The method of claim 6, wherein the method further comprises, The step of calibrating the drilling direction using a positioning and calibration structure and marking the position of the mounting hole to ensure that the energy-concentrating zone corresponds to the preset cracking direction of the rock specimen substrate after the blasting device is placed in the mounting hole includes: A laser level is set up and a laser beam is emitted to determine the relative position of the rock specimen substrate and the laser beam. The angle of the drilling table is adjusted according to the relative position so that the side of the rock specimen substrate is parallel to the laser beam. Move the rock specimen substrate so that the laser beam is projected perpendicularly at the geometric center of the borehole area; Adjust the position of the drilling machine and the angle of the drill bit so that the extension direction of the drill bit coincides with the laser beam.
8. The method for preparing rock structural surfaces based on two-dimensional blasting according to claim 6, characterized in that, The step of drilling in the drilling area and keeping the hole depth error within a preset range includes: Drilling at the first preset feed rate; Stop drilling after reaching the first preset depth and remove debris from the hole; Repeat the above steps until the drilling depth is less than the target depth by a second preset depth. Then reduce the feed rate to the second preset feed rate and continue drilling to the target depth.
9. The method for preparing rock structural surfaces based on two-dimensional blasting according to claim 1, characterized in that, The step of detonating the blasting device includes using an image acquisition device to simultaneously record the crack propagation morphology of the rock specimen substrate during the blasting process.
10. The method for preparing rock structural surfaces based on two-dimensional blasting according to claim 1, characterized in that, The preparation of the blasting device includes a shaped charge tube and an expanding agent disposed inside the shaped charge tube. The wall of the shaped charge tube has two shaped charge zones arranged radially opposite each other. Multiple shaped charge holes are opened on the shaped charge zones and spaced apart along the axial direction of the shaped charge tube. The outer diameter of the shaped charge tube matches the inner diameter of the mounting hole. The shaped charge tube is manufactured by 3D printing.