A hard rock explosion testing system and method under deep geostress environment

Abstract

The application discloses a hard rock explosion test system and method under deep geostress environment, and belongs to the technical field of rock blasting optimization design. The system comprises a geostress hydraulic loading module, a sample bearing module, a blasting occurrence module, a non-contact optical measurement module and an automatic triggering device. The method comprises the following steps: processing a sample, assembling the system, laying out a blasting structure, processing the surface of the sample, loading geostress, preparing for measurement, performing explosion test and processing data. The system and method solve the blank of a large-size and large-equivalent blasting test platform and analysis means under deep in-situ geostress. A digital image correlation analysis system with parallel and efficient calculation is constructed, and explosion pressure field can be quickly inverted.

Description

Technical Field

[0001] This invention relates to the field of rock blasting optimization design technology, and in particular to a hard rock blasting test system and method under deep geostress environment. Background Technology

[0002] In the field of hard rock explosion stress wave testing, the application scenarios of existing testing devices are significantly limited, mostly concentrated in shallow buried rock layers, which cannot meet the testing needs of deep geostress environments; moreover, their core component, the sensor, generally has insufficient pressure bearing capacity, and is prone to failure when subjected to static-dynamic coupled loads at the moment of explosion, which directly leads to a sharp drop in the accuracy of the measurement signal and makes it difficult to obtain accurate stress data. This problem directly affects the subsequent analysis and application of the characteristics of explosion stress waves.

[0003] Current mainstream hard rock explosion stress wave measurement schemes mostly adopt electrical measurement methods, using quartz pressure gauges or embedded anchor stress gauges in conjunction with integrated multi-channel optical fibers for data acquisition. However, this type of method can only achieve single-point stress measurement. Under the influence of strong blast stress pulses, it not only cannot accurately reflect the spatiotemporal evolution information of stress waves, but also cannot comprehensively describe the complete explosion stress field. As a result, the test results cannot support the effective reconstruction of the explosion stress wave propagation process, and it is difficult to meet the engineering requirements for refined stress field analysis.

[0004] The existing measuring devices have technical defects in the installation process. They need to be installed by drilling, but the hole wall is prone to deformation after drilling, and the coupling medium may fall off. These two problems will directly cause a sudden change in wave impedance, which will lead to distortion of stress waveform, further reducing the reliability of test data and adversely affecting subsequent work such as rock blasting optimization and underground protection design based on test data.

[0005] In terms of testing capabilities, existing technical solutions cannot handle large-scale, high-yield explosion experiments (most current explosion experiments use only 50mg-100mg of explosives), and do not consider the impact of deep ground stress on explosion stress waves. They also suffer from insufficient spatial resolution and large synchronization errors, making it difficult to achieve high-precision synchronous recording. They cannot meet the actual needs of fields such as deep underground engineering safety, rock blasting optimization design, and underground protection and impact-resistant engineering for accurate testing of hard rock explosion stress waves. The relevant technical gaps urgently need to be filled with targeted solutions. Summary of the Invention

[0006] The purpose of this invention is to provide a hard rock explosion testing system and method under deep geostress environment to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides a hard rock explosion testing system under deep in-situ stress conditions, comprising an in-situ stress hydraulic loading module, a sample bearing module, an explosion generation module, a non-contact optical measurement module, and an automatic triggering device:

[0008] The ground stress hydraulic loading module includes an oil tank, a jack, a step-by-step loading valve, an oil pressure gauge, and an electrical control cabinet. The oil tank is connected to the jack through a hydraulic oil pipeline. The step-by-step loading valve and the oil pressure gauge are installed on the hydraulic oil pipeline. The electrical control cabinet is electrically connected to the step-by-step pressure valve.

[0009] The sample bearing module includes a sample block cut from the working face of the original construction site. The sample block has a grooved area machined around its perimeter to create a gap between the sample block and the bedrock of the working face. Multiple jacks are evenly distributed around the sample block and contact the sample block through a top plate.

[0010] The blasting module includes a blast hole located at the center of the sample block, a fume hood, and a negative pressure exhaust power module. The fume hood covers the outside of the blast hole, and the negative pressure exhaust power module is connected to the fume hood through a pipe.

[0011] The non-contact optical measurement module includes a speckle pattern sprayed on the surface of the sample block and a high-speed camera aligned with the speckle pattern.

[0012] The automatic triggering device is electrically connected to the high-speed camera and the detonator located inside the blast hole.

[0013] Preferably, the oil tank is a closed container with a filter element and is equipped with liquid level and oil temperature sensors; the jack is a plunger jack or a hollow cylinder jack, and the jacks are symmetrically distributed around the circumference of the sample block; the hydraulic oil pipeline is a pressure-resistant hose with anti-corrosion and wear-resistant treatment on the inner wall.

[0014] Preferably, the step-by-step loading valve is a multi-stage throttling control valve or a proportional control valve, and the oil pressure gauge is a high-precision pressure indicator.

[0015] Preferably, the electrical control cabinet is a closed control box integrating relays, servo drives and human-machine interfaces, and the electrical control cabinet is electrically connected to the negative pressure exhaust power module.

[0016] Preferably, the grooved area is a rectangular or square groove, and the top plate is a high-strength rigid pressure plate.

[0017] Preferably, the blast hole is a cylindrical charging hole, the fume hood is a metal shell, the negative pressure exhaust power module includes a high-flow vacuum pump, an anti-wear filter cartridge and a check valve, the check valve is installed on the pipe between the negative pressure exhaust power module and the fume hood, and the anti-wear filter cartridge is installed at the air inlet of the high-flow vacuum pump.

[0018] Preferably, the speckle pattern is a high-contrast black and white random speckle pattern, and the high-speed camera is a high-frame-rate optical acquisition device.

[0019] A method for explosive testing of hard rock under deep in-situ stress conditions includes the following steps:

[0020] S1. Select a hard rock area on the in-situ working face that is consistent with the surrounding rock of the tunnel, and form a sample block by mechanical cutting. At the same time, cut a groove area around the sample block to form a gap of 5-10mm between the sample block and the bedrock of the in-situ working face.

[0021] S2. Connect the oil tank, step-by-step loading valve, and jacks in sequence through the hydraulic oil pipeline. Connect the oil pressure gauge in series or in parallel to the hydraulic oil pipeline. Connect the electrical control cabinet to the step-by-step loading valve. Arrange multiple jacks evenly around the circumference of the sample block and install a top plate between the jacks and the sample block.

[0022] S3. Drill a blast hole at the center axis of the sample block, load explosives and an initiator into the blast hole, cover the blast hole opening with a fume hood, and connect the fume hood to the negative pressure exhaust power module through a pipe with a check valve.

[0023] S4. Spray matte white primer onto the surface of the sample block facing the high-speed camera. After the primer has cured, spray black random spots onto the primer surface to form a speckle pattern.

[0024] S5. Start the step-by-step loading valve through the electrical control cabinet to deliver hydraulic oil to the jack to push the top plate to apply confining pressure to the sample block. Monitor the loading pressure in real time through the oil pressure gauge until the confining pressure reaches the set value of the deep ground stress in the restored original state and remains stable.

[0025] S6. Adjust the position of the high-speed camera so that the speckle pattern is completely within the camera's field of view. Set the camera's frame rate and complete the size calibration. Connect the automatic triggering device to the high-speed camera and the detonator respectively.

[0026] S7. Start the negative pressure extraction power module. After the personnel have evacuated to a safe distance, the detonator is triggered by the automatic triggering device to detonate the explosive. At the same time, the automatic triggering device controls the high-speed camera to collect the image sequence of the speckle pattern.

[0027] S8. The acquired image sequence is analyzed using the digital image correlation method to solve the displacement field and strain field on the surface of the sample block. The explosion stress wave field is obtained by combining the lithological parameters of the sample block.

[0028] Preferably, the digital image correlation method in S8 includes the following steps:

[0029] S81. Import the speckle image sequence into the graphical user interface, filter and load the valid frames;

[0030] S82. Based on the area of ​​the computing region of the effective frame segment and the CPU computing power resources, evenly distribute parallel computing seeds within the computing region.

[0031] S83. Based on the parallel computing seed, pixel matching calculation is performed on the effective frame segment to solve for the displacement field and strain field on the surface of the sample block.

[0032] S84. Input the lithological parameters of the sample block, and invert the explosion wave pressure field by combining the displacement field and strain field data;

[0033] S85. Select characteristic points in the explosion wave pressure field according to the test requirements, and calculate the peak pressure, wave velocity and duration parameters of the explosion wave at the characteristic points.

[0034] Therefore, the present invention employs the above-mentioned hard rock explosion testing system and method under deep geostress environment, which has the following beneficial effects:

[0035] (1) It can simulate deep ground stress and is suitable for large-size, high-yield explosion tests. It can accurately restore the deep ground stress environment through the ground stress hydraulic loading module, and can withstand the high-yield blast of 30-60g explosives (600 times higher than the existing 50mg-100mg low-yield experiments). It solves the problem that the existing technology cannot cope with large-size, high-yield explosions and does not take into account the influence of deep ground stress, and matches the testing needs of deep engineering.

[0036] (2) It has both high-precision full-field acquisition and rapid stress wave inversion capabilities. It achieves high-precision synchronization and full-field acquisition through non-contact optical measurement. By using a high-speed camera with a frame rate of ≥50kfps and a speckle pattern, it improves spatial resolution and reduces synchronization error, thus achieving high-precision synchronous recording. At the same time, it combines digital image correlation method to obtain the complete explosion stress wave field. Relying on the parallel and efficient digital image correlation analysis system, it can quickly solve the displacement-strain field and invert the explosion pressure field, thus solving the limitations of existing technologies such as insufficient spatial resolution, large synchronization error, and the ability to measure only a single point.

[0037] (3) No need to drill holes to install sensors, avoiding waveform distortion caused by borehole wall deformation or coupling medium detachment, improving the reliability of test data, providing accurate data support for deep underground engineering safety, rock blasting optimization design and other fields, and solving the problem of data distortion caused by drilling in existing technologies.

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a hard rock explosion testing system device under deep geostress environment according to the present invention;

[0040] Figure 2 This is a flowchart of a method for testing hard rock explosions under deep geostress conditions according to the present invention.

[0041] Figure 3 This invention provides a digital image correlation calculation module and flowchart for a hard rock explosion testing method under deep geostress conditions.

[0042] Figure 4 This is a diagram showing the inversion results of the explosion stress wave pressure field of a hard rock explosion testing system and method under deep geostress conditions according to the present invention. Detailed Implementation

[0043] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0044] Example

[0045] like Figure 1 As shown, this invention provides a hard rock explosion testing system under deep in-situ stress conditions, including an in-situ stress hydraulic loading module, a sample bearing module, an explosion generation module, a non-contact optical measurement module, and an automatic triggering device.

[0046] The ground stress hydraulic loading module includes an oil tank, a jack, a step-by-step loading valve, an oil pressure gauge, and an electrical control cabinet. The oil tank is connected to the jack through a hydraulic oil pipeline, which delivers high-pressure hydraulic oil from the oil tank to the jack. The step-by-step loading valve and the oil pressure gauge are connected in series or in parallel to the hydraulic oil pipeline. The electrical control cabinet is electrically connected to the step-by-step pressure valve.

[0047] The oil tank is a closed container with a filter element that stores and cools hydraulic oil. It is equipped with level and temperature sensors to provide circulating working medium for the hydraulic stress loading module. The jacks are hydraulically driven plunger jacks or hollow cylinder jacks, which are evenly distributed around the sample to apply anisotropic confining pressure to simulate in-situ stress. The hydraulic oil pipeline is a pressure-resistant hose with a maximum designed working pressure of 100MPa and the inner wall is treated with anti-corrosion and wear-resistant coating.

[0048] The progressive loading valve is a multi-stage throttling control valve or proportional control valve assembly used to implement phased, constant-speed, or constant-pressure loading of the hydraulic system to achieve fine adjustment of the confining pressure; the oil pressure gauge is a high-precision pressure indicator connected in parallel with the hydraulic oil pipeline, with a measurement range of 0–100MPa, used to monitor and calibrate the loading pressure in real time; the electrical control cabinet is a closed control box integrating relays, servo drives, and human-machine interfaces, responsible for the linkage logic control of the jacks, valve groups, and smoke exhaust system, and the electrical control cabinet is electrically connected to the negative pressure exhaust power module.

[0049] The sample bearing module includes a sample block cut from the working face of the original construction site. The sample block has a grooved area machined around its perimeter to create a gap between the sample block and the bedrock of the working face. Multiple jacks are evenly distributed around the sample block and contact the sample block through the top plate.

[0050] In this embodiment, the sampling substrate for the sample block is outcrop rock, which refers to natural hard rock that is directly exposed on the surface and has the same lithology as the surrounding rock of deep tunnels. The groove area is a rectangular or square groove area mechanically processed on the outcrop rock to embed the controlled sample block and form a loadable gap around it. The top plate is a high-strength rigid pressure plate placed around the sample to bear and homogenize the confining pressure.

[0051] The blasting module includes a blast hole located at the center of the sample block, a fume hood, and a negative pressure exhaust power module. The fume hood covers the outside of the blast hole, and the negative pressure exhaust power module is connected to the fume hood through a pipe.

[0052] The blast hole is a cylindrical charging hole drilled at the center of the sample, used to place the explosive and form a directional blasting source; the fume hood is a metal shell installed on the outer wall of the blast hole to cover the fracture zone. At the moment of blasting, it works with the negative pressure extraction power module to form an airflow channel to collect and isolate smoke and dust; the negative pressure extraction power module includes a high-flow vacuum pump, a wear-resistant filter cartridge, and a check valve, used to drive the fume hood to remove dust. The check valve is installed on the pipe between the negative pressure extraction power module and the fume hood, and the wear-resistant filter cartridge is installed at the air inlet of the high-flow vacuum pump.

[0053] The non-contact optical measurement module includes a speckle pattern sprayed onto the surface of the sample block and a high-speed camera aligned with the speckle pattern. The speckle pattern is a random high-contrast black and white spot pattern applied to the front of the sample, which is used by digital image correlation algorithms to identify and invert the explosion stress wave field. The high-speed camera is a non-contact optical sensor with a frame rate of ≥50kfps, which, together with synchronous illumination, acquires speckle sequence images of the entire blasting process for analysis by digital image correlation.

[0054] The automatic triggering device is electrically connected to the high-speed camera and the detonator located in the blast hole, respectively, to realize the synchronous control of the explosive detonation and the high-speed camera image acquisition, trigger the high-speed camera to enter the exposure state, and at the same time, coordinately start the negative pressure exhaust power device to collect blasting smoke and dust to ensure image clarity.

[0055] like Figure 2 As shown, a method for explosive testing of hard rock under deep geostress conditions includes the following steps:

[0056] S1. Select a hard rock area on the working face that is consistent with the surrounding rock of the tunnel, and form a sample block by mechanical cutting. At the same time, cut a groove area around the sample block to form a gap of 5-10mm between the sample block and the bedrock of the working face. In this embodiment, a rectangular groove area is milled in the outcrop rock mass with the same lithology as the underground tunnel.

[0057] S2. Connect the oil tank, step-by-step loading valve, and jacks in sequence through the hydraulic oil pipeline. Connect the oil pressure gauge in series or in parallel to the hydraulic oil pipeline. Connect the electrical control cabinet to the step-by-step loading valve. Arrange multiple jacks evenly around the circumference of the sample block and install a top plate between the jacks and the sample block.

[0058] S3. Drill a blast hole at the center axis of the sample block, load explosives and an initiator into the blast hole, cover the blast hole opening with a fume hood, and connect the fume hood to the negative pressure exhaust power module through a pipe with a check valve.

[0059] S4. Spray matte white primer onto the surface of the sample block facing the high-speed camera. After the primer has cured, spray black random spots onto the primer surface to form a speckle pattern.

[0060] S5. Start the step-by-step loading valve through the electrical control cabinet to deliver hydraulic oil to the jack to push the top plate to apply confining pressure to the sample block. Monitor the loading pressure in real time through the oil pressure gauge until the confining pressure reaches the set value of the deep ground stress in the restored original state and remains stable.

[0061] S6. Adjust the position of the high-speed camera so that the speckle pattern is completely within the camera's field of view. Set the camera's frame rate and complete the size calibration. Connect the automatic triggering device to the high-speed camera and the detonator respectively.

[0062] S7. Start the negative pressure extraction power module. After the personnel have evacuated to a safe distance, the detonator is triggered by the automatic triggering device to detonate the explosive. At the same time, the automatic triggering device controls the high-speed camera to collect the image sequence of the speckle pattern.

[0063] S8. The acquired image sequence is analyzed using the digital image correlation method to solve the displacement field and strain field on the surface of the sample block. The explosion stress wave field is obtained by combining the lithological parameters of the sample block.

[0064] like Figure 3 As shown, the digital image correlation method includes the following steps:

[0065] S81. Import the speckle image sequence into the graphical user interface, filter and load the valid frames;

[0066] S82. Based on the area of ​​the computing region of the effective frame segment and the CPU computing power resources, evenly distribute parallel computing seeds within the computing region.

[0067] S83. Based on the parallel computing seed, pixel matching calculation is performed on the effective frame segment to solve for the displacement field and strain field on the surface of the sample block.

[0068] S84. Input the lithological parameters of the sample block, and invert the explosion wave pressure field by combining the displacement field and strain field data;

[0069] S85. Select characteristic points in the explosion wave pressure field according to the test requirements, and calculate the peak pressure, wave velocity and duration parameters of the explosion wave at the characteristic points.

[0070] The explosion stress wave pressure field inversion results obtained using the method of this embodiment are as follows: Figure 4 As shown.

[0071] Therefore, the present invention adopts the above-mentioned hard rock explosion test system and method under deep in-situ stress environment, which fills the gap in the test platform and analysis means for large-size and high-yield blasting tests under deep in-situ stress; and constructs a parallel and efficient digital image correlation analysis system that can quickly invert the explosion pressure field.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A hard rock explosion testing system under deep geostress environment, characterized in that, It includes a geostress hydraulic loading module, a sample bearing module, a bursting generation module, a non-contact optical measurement module, and an automatic triggering device. The ground stress hydraulic loading module includes an oil tank, a jack, a step-by-step loading valve, an oil pressure gauge, and an electrical control cabinet. The oil tank is connected to the jack through a hydraulic oil pipeline. The step-by-step loading valve and the oil pressure gauge are installed on the hydraulic oil pipeline. The electrical control cabinet is electrically connected to the step-by-step pressure valve. The sample bearing module includes a sample block cut from the working face in the construction site. The sample block has a grooved area machined around its perimeter to create a gap between the sample block and the bedrock of the working face. Multiple jacks are evenly distributed around the sample block and contact the sample block through a top plate. The blasting module includes a blast hole located at the center of the sample block, a fume hood, and a negative pressure exhaust power module. The fume hood covers the outside of the blast hole, and the negative pressure exhaust power module is connected to the fume hood through a pipe. The blast hole is a cylindrical charging hole, the fume hood is a metal shell, the negative pressure extraction power module includes a high flow vacuum pump, a wear-resistant filter cartridge and a check valve, the check valve is installed on the pipe between the negative pressure extraction power module and the fume hood, and the wear-resistant filter cartridge is installed at the air inlet of the high flow vacuum pump. The non-contact optical measurement module includes a speckle pattern sprayed on the surface of the sample block and a high-speed camera aligned with the speckle pattern. The automatic triggering device is electrically connected to the high-speed camera and the detonator located inside the blast hole.

2. The hard rock explosion testing system under deep geostress environment according to claim 1, characterized in that: The oil tank is a closed container with a filter element and is equipped with liquid level and oil temperature sensors; the jack is a plunger jack or a hollow cylinder jack, and the jacks are symmetrically distributed around the circumference of the sample block; the hydraulic oil pipeline is a pressure-resistant hose with anti-corrosion and wear-resistant treatment on the inner wall.

3. The hard rock explosion testing system under deep geostress environment according to claim 1, characterized in that: The step-by-step loading valve is a multi-stage throttling control valve or a proportional control valve, and the oil pressure gauge is a high-precision pressure indicator.

4. The hard rock explosion testing system under deep geostress environment according to claim 1, characterized in that: The electrical control cabinet is a closed control box integrating relays, servo drives and human-machine interfaces, and the electrical control cabinet is electrically connected to the negative pressure exhaust power module.

5. The hard rock explosion testing system under deep geostress environment according to claim 1, characterized in that: The grooved area is a rectangular or square groove, and the top plate is a high-strength rigid pressure plate.

6. The hard rock explosion testing system under deep geostress environment according to claim 1, characterized in that: The speckle pattern is a random speckle pattern, and the high-speed camera is a high frame rate optical acquisition device.

7. A method for testing hard rock under deep geostress conditions, applied to a hard rock explosion testing system under deep geostress conditions as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Select a hard rock area on the in-situ working face that is consistent with the surrounding rock of the tunnel, and form a sample block by mechanical cutting. At the same time, cut a groove area around the sample block to form a gap of 5-10mm between the sample block and the bedrock of the in-situ working face. S2. Connect the oil tank, step-by-step loading valve, and jacks in sequence through the hydraulic oil pipeline. Connect the oil pressure gauge in series or in parallel to the hydraulic oil pipeline. Connect the electrical control cabinet to the step-by-step loading valve. Arrange multiple jacks evenly around the circumference of the sample block and install a top plate between the jacks and the sample block. S3. Drill a blast hole at the center axis of the sample block, load explosives and an initiator into the blast hole, cover the blast hole opening with a fume hood, and connect the fume hood to the negative pressure exhaust power module through a pipe with a check valve. S4. Spray matte white primer onto the surface of the sample block facing the high-speed camera. After the primer has cured, spray black random spots onto the primer surface to form a speckle pattern. S5. Start the step-by-step loading valve through the electrical control cabinet to deliver hydraulic oil to the jack to push the top plate to apply confining pressure to the sample block. Monitor the loading pressure in real time through the oil pressure gauge until the confining pressure reaches the set value of the deep ground stress in the restored original state and remains stable. S6. Adjust the position of the high-speed camera so that the speckle pattern is completely within the camera's field of view. Set the camera's frame rate and complete the size calibration. Connect the automatic triggering device to the high-speed camera and the detonator respectively. S7. Start the negative pressure extraction power module. After the personnel have evacuated to a safe distance, the detonator is triggered by the automatic triggering device to detonate the explosive. At the same time, the automatic triggering device controls the high-speed camera to collect the image sequence of the speckle pattern. S8. The acquired image sequence is analyzed using the digital image correlation method to solve the displacement field and strain field on the surface of the sample block. The explosion stress wave field is obtained by combining the lithological parameters of the sample block.

8. A method for explosive testing of hard rock under deep geostress environment as described in claim 7, characterized in that, The digital image correlation method in S8 includes the following steps: S81. Import the speckle image sequence into the graphical user interface, filter and load the valid frames; S82. Based on the area of ​​the computing region of the effective frame segment and the CPU computing power resources, evenly distribute parallel computing seeds within the computing region. S83. Based on the parallel computing seed, pixel matching calculation is performed on the effective frame segment to solve for the displacement field and strain field on the surface of the sample block. S84. Input the lithological parameters of the sample block, and invert the explosion wave pressure field by combining the displacement field and strain field data; S85. Select characteristic points in the explosion wave pressure field according to the test requirements, and calculate the peak pressure, wave velocity and duration parameters of the explosion wave at the characteristic points.

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