Instantaneous rock breaking specific energy measuring method

Abstract

The invention discloses an instantaneous rock breaking specific energy measuring method which comprises the following steps: carrying out a cutting test on a test rock mass, collecting instantaneous cutting resistance on a cutting path, and cleaning rock debris in a groove; the two sides of the groove are each provided with a mark belt, each mark belt is provided with a plurality of irregularly-distributed mark points, and the groove and the two mark belts form an area to be scanned; in the length direction of the groove, n sub-scanning areas which are overlapped in sequence are arranged in the to-be-scanned area; scanning the n sub-scanning areas in sequence to obtain n groups of point cloud data; splicing the point cloud data of the n sub-scanning areas to obtain complete point cloud data of the groove; and a three-dimensional groove model is established, and instantaneous rock breaking specific energy on the cutting path is calculated. According to the method, the local energy consumption condition in the rock breaking process can be more accurately captured, the real rock breaking efficiency can be more accurately reflected, and an accurate and effective method can be provided for measuring the rock breaking specific energy of heterogeneous rock or rock with cracks.

Description

Technical Field

[0001] The invention belongs to the field of mechanical rock breaking efficiency testing, and in particular relates to a method for measuring instantaneous rock breaking specific energy. Background Art

[0002] Mechanical rock breaking methods are widely used in mining, water conservancy, highways, railways, rail transit and other fields due to their advantages such as fast excavation speed, high safety and low disturbance intensity to the surrounding strata. Rock breaking specific energy is a key indicator for evaluating the efficiency of mechanical rock breaking and is often used to predict excavation efficiency. It is defined as the energy dissipated by cutting a unit volume of rock. It can directly reflect the energy consumption in the process of mechanical rock breaking and indirectly explain the performance of the equipment and the construction efficiency. Therefore, accurate measurement of rock breaking specific energy is of great significance for guiding rock breaking operations in actual projects and optimizing equipment operating parameters.

[0003] The traditional method for determining rock-breaking specific energy is the weighing inverse algorithm, which is to weigh the rock cuttings produced by cutting, and then combine the density of the rock cuttings to calculate the volume of the cut rock, and then calculate the average rock-breaking specific energy. It can provide relatively reasonable measurement results under homogeneous and isotropic rock conditions. However, the traditional weighing inverse algorithm relies on the estimation of the cutting volume, which is easily affected by a variety of uncertain factors. For example, during the rock-breaking process, there may be errors in the collection and weighing of the rock cuttings, and the calculation of the cutting volume depends on the accuracy of the rock density, which may not be consistent in different rock types or even in different regions of the same rock. These factors will cause the traditional weighing method to be inaccurate in determining the rock-breaking specific energy. At the same time, the weighing method obtains the average result of the entire cutting path, lacking the reflection of the energy consumption differences in the local area. In fact, during the rock crushing process, due to the heterogeneity and anisotropy of the rock, the rock-breaking energy consumption along the cutting line will show obvious fluctuations. For example, factors such as cracks in the rock can cause the three-dimensional rock-breaking force and the cross-sectional area of ​​the cutting groove to fluctuate violently at different positions, which in turn leads to huge differences in the rock-breaking specific energy along the cutting line. For another example, microwave-assisted mechanical rock breaking is a new type of rock-breaking method. Microwave irradiation can cause cracks in the rock, thereby reducing the energy consumption of subsequent mechanical rock breaking. The rock after microwave irradiation has the characteristics of uneven damage distribution in the plane and depth. On the plane, the closer to the microwave radiation point, the greater the damage; in depth, the shallower the radiation depth, the greater the damage. In order to study the effect of microwave irradiation on the subsequent mechanical rock-breaking efficiency, it is necessary to accurately obtain the instantaneous rock-breaking specific energy at different positions on the rock-breaking path. In this case, simply evaluating the rock-breaking specific energy by averaging the results of the entire cutting line often fails to reflect the actual rock-breaking efficiency, nor can it achieve the purpose of the study, which may cover up some potential problems in actual operation.

[0004] In conclusion, rock breaking specific energy, as a core indicator for evaluating mechanical rock breaking efficiency, is of great significance for guiding the selection and operation of rock breaking equipment. The traditional weighing method has limited accuracy under the conditions of inhomogeneous or cracked rocks. The present invention provides a method for measuring instantaneous rock breaking specific energy, which can provide an accurate and effective method for measuring the rock breaking specific energy of inhomogeneous or cracked rocks. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for measuring instantaneous rock breaking specific energy in view of the deficiencies in the prior art, so as to more accurately capture the local energy consumption in the rock breaking process and more accurately reflect the actual rock breaking efficiency.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a method for measuring instantaneous rock breaking specific energy, comprising the following steps: S1. Use the mechanical rock breaking test platform to conduct a cutting test on the test rock mass, use a three-axis force sensor to collect the instantaneous cutting resistance on the cutting path, and clean the rock chips in the grooves generated by the cutting test; S2. A marking belt is arranged on each side of the groove, each marking belt is arranged along the length direction of the groove, and each marking belt is provided with a plurality of irregularly distributed marking points, and the distance between two adjacent marking points is less than 3 cm. The groove and the two marking belts constitute a to-be-scanned area, and the length of the to-be-scanned area is l cm; S3. Arrange n sub-scanning areas in the area to be scanned along the length direction of the groove, where n is an integer greater than 1, and the length of each sub-scanning area is 20-25 cm. The n sub-scanning areas overlap in sequence, and the overlapping length of two adjacent sub-scanning areas is not less than 10 cm. The area to be scanned falls within the orthographic projection of the n sub-scanning areas. The calculation formula of n is: ; S4, scanning the n sub-scanning areas in sequence along the length direction of the groove using a three-dimensional laser scanner to obtain n groups of point cloud data, each group of the point cloud data includes spatial three-dimensional coordinates, and each group of the point cloud data corresponds to one sub-scanning area; S5. Using the point cloud data of the common marking points of two adjacent sub-scanning areas as a reference, using Geomagic software to splice the point cloud data of the n sub-scanning areas to obtain complete point cloud data of the groove; S6. A three-dimensional groove model is established according to the complete point cloud data of the groove, and the instantaneous cross-sectional area of ​​the groove is calculated using Geomagic software. According to the instantaneous cutting resistance on the cutting path collected in step S1 and the instantaneous cross-sectional area of ​​the groove, the instantaneous rock breaking specific energy on the cutting path is calculated. The calculation formula of the instantaneous rock breaking specific energy is: ; In formula (2): SE( t ) is the instantaneous rock breaking specific energy, in J / m 3 ; F r ( t ) is the instantaneous cutting resistance on the cutting path, in N; is the instantaneous cutting speed, in m / s; A ( t ) is the instantaneous cross-sectional area of ​​the groove, in m 2 ; t is the cutting time of the groove.

[0007] Compared with the prior art, the present invention has the following advantages: the method of the present invention can more accurately capture the local energy consumption in the rock breaking process, more accurately reflect the actual rock breaking efficiency, and can provide an accurate and effective method for measuring the rock breaking specific energy of heterogeneous or cracked rocks. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a schematic diagram of a top view of a scene when the instantaneous rock breaking specific energy is measured by the method of the present invention in an embodiment; Figure 2 The average rock-breaking specific energy obtained by the traditional weighing inverse algorithm (red dotted line) and the instantaneous rock-breaking specific energy obtained by the method of the present invention (black solid line) are shown. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention, but should not be used to limit the scope of protection of the present invention.

[0010] Taking the cutting test of diorite rock mass after combined point microwave irradiation as an example, the method of the present invention and the traditional weighing inverse algorithm are used to measure the rock breaking specific energy respectively.

[0011] 1. Example: Determination of instantaneous rock breaking specific energy by the method of the present invention After microwave irradiation, the rock has the characteristics of uneven damage distribution in plane and depth. On the plane, the closer to the microwave radiation point, the greater the damage; in depth, the shallower the radiation depth, the greater the damage. The three-dimensional rock-breaking force on the cutting path and the cross-sectional area of ​​the grooves produced by cutting fluctuate violently, which leads to huge differences in rock-breaking specific energy on the cutting path.

[0012] Assuming that the size of the test rock mass is 100cm×100cm×30cm (length×width×thickness), the test rock mass is radiated by microwave, the microwave power is set to 6 kW, and the irradiation time is set to 2 min. A total of four microwave radiation points 7 are arranged, and the spacing between adjacent microwave radiation points 7 is 15 cm.

[0013] The steps of measuring instantaneous rock breaking specific energy by the method of the present invention are as follows: S1. Use the mechanical rock breaking test platform to conduct a pick cutting test on the test rock mass after microwave irradiation. The cutting depth is 2.5 mm, the cutting speed is 0.03 m / s, and the cutting length is 100 cm. The instantaneous cutting resistance on the cutting path is collected using a three-axis force sensor. F r ( t ); S2, such as Figure 1 As shown, a marking strip 3 is arranged on both sides of the groove 5, each marking strip 3 is arranged along the length direction of the groove 5, and each marking strip 3 is provided with a plurality of irregularly distributed (horizontally and vertically) marking points 4, and the distance between two adjacent marking points 4 is less than 3 cm. The groove 5 and the two marking strips 3 constitute a to-be-scanned area, and the length of the to-be-scanned area is l is 100 cm; S3, such as Figure 1 As shown, along the length direction of the groove 5, n sub-scanning areas are arranged in the area to be scanned, where n is an integer greater than 1, that is, the first sub-scanning area 1 (i.e. Figure 1 The area indicated by the orange solid line box on the left), the second sub-scan area 2 (i.e. Figure 1 The area indicated by the orange dotted line box on the left side of the middle, the orange dotted line box and the orange solid line box corresponding to the first sub-scanning area 1 have a certain overlap in the length direction of the groove), ..., the nth sub-scanning area 6 (i.e. Figure 1 The length of each sub-scanning area is 20-25 cm, and the n sub-scanning areas overlap in sequence. The overlapping length of two adjacent sub-scanning areas is not less than 10 cm. The area to be scanned falls within the orthographic projection of the n sub-scanning areas. The calculation formula of n is: ; In this embodiment, n is set to 10; S4, scanning 10 sub-scanning areas in sequence along the length direction of the groove using a three-dimensional laser scanner to obtain 10 sets of point cloud data, each set of point cloud data including spatial three-dimensional coordinates, and each set of point cloud data corresponding to a sub-scanning area; S5. Using the point cloud data of the common marker points of two adjacent sub-scanning areas as a reference, the point cloud data of the 10 sub-scanning areas are spliced ​​using Geomagic software to obtain complete point cloud data of the groove; S6. A three-dimensional groove model is established according to the complete point cloud data of the groove, and the instantaneous cross-sectional area of ​​the groove is calculated using Geomagic software. According to the instantaneous cutting resistance on the cutting path collected in step S1 and the instantaneous cross-sectional area of ​​the groove, the instantaneous rock breaking specific energy on the cutting path is calculated. The calculation formula of the instantaneous rock breaking specific energy is: ; In formula (2): SE( t ) is the instantaneous rock breaking specific energy, in J / m 3 ; F r ( t ) is the instantaneous cutting resistance on the cutting path, in N; is the instantaneous cutting speed, in m / s; A ( t ) is the instantaneous cross-sectional area of ​​the groove, in m 2 ; t is the cutting time of the groove.

[0014] The instantaneous rock breaking specific energy on the cutting path of the test rock mass after microwave irradiation measured by the method of the present invention is as follows: Figure 2 The results show that when the pick is close to the microwave radiation area, the rock breaking energy ratio decreases significantly; when the pick is far away from the microwave radiation area, the rock breaking energy ratio increases suddenly.

[0015] 2. Comparative example: Using traditional weighing inverse algorithm to determine rock breaking specific energy Assuming that the size of the test rock mass is 100cm×100cm×30cm (length×width×thickness), the test rock mass is radiated by microwave, the microwave power is set to 6 kW, and the irradiation time is set to 2 min. Similarly, four microwave radiation points are arranged, and the spacing between adjacent microwave radiation points 7 is 15 cm.

[0016] The steps for determining the average rock breaking specific energy of the test using the traditional weighing inverse algorithm are as follows: The mechanical rock breaking test platform was used to carry out a pick cutting test on the test rock mass after microwave irradiation. The cutting depth was 2.5 mm, the cutting speed was 0.03 m / s, and the cutting length was 100 cm. The average cutting force on the cutting path was collected using a three-axis force sensor.F r ; Collect the rock chips produced by cutting and weigh them, and use formula (3) to calculate the average rock breaking specific energy: ; In formula (3), SE is the average rock breaking specific energy, in J / m 3 ; F r is the average cutting force, in N; d is the effective cutting length of the pick, in m; m is the weight of the rock cuttings produced in the cutting test, in kg; ρ is the density of the test rock mass (the density of diorite is 2840 kg / m 3 ).

[0017] like Figure 2 As shown by the red dotted line in the middle, the average rock breaking specific energy measured by the traditional weighing inverse algorithm is 1.06×10 9 J / m 3 .

[0018] 3. Comparison of the two methods Figure 2 The average rock-breaking specific energy obtained by the traditional weighing inverse algorithm (red dashed line) and the instantaneous rock-breaking specific energy obtained by the method of the present invention (black solid line) are shown.

[0019] The instantaneous rock-breaking specific energy obtained by the method of the present invention can clearly and accurately show the influence of damage induced by microwave irradiation on the mechanical rock-breaking efficiency, while the traditional weighing inverse algorithm can only obtain an average rock-breaking specific energy data, which fails to reflect the influence of the heterogeneity of the rock mass after microwave irradiation on the rock-breaking specific energy result. This further illustrates that the method of the present invention can more accurately capture the local energy consumption in the rock-breaking process and more accurately reflect the actual rock-breaking efficiency, and can provide an accurate and effective method for measuring the rock-breaking specific energy of heterogeneous rocks or rocks with cracks.

Claims

1. A method for measuring instantaneous rock breaking specific energy, characterized in that: The following steps are involved: S1. Use the mechanical rock breaking test platform to conduct a cutting test on the test rock mass, use a three-axis force sensor to collect the instantaneous cutting resistance on the cutting path, and clean the rock chips in the grooves generated by the cutting test; S2. A marking belt is arranged on each side of the groove, each marking belt is arranged along the length direction of the groove, and each marking belt is provided with a plurality of irregularly distributed marking points, and the distance between two adjacent marking points is less than 3 cm. The groove and the two marking belts constitute a to-be-scanned area, and the length of the to-be-scanned area is l cm; S3. Arrange n sub-scanning areas in the area to be scanned along the length direction of the groove, where n is an integer greater than 1, and the length of each sub-scanning area is 20-25 cm. The n sub-scanning areas overlap in sequence, and the overlapping length of two adjacent sub-scanning areas is not less than 10 cm. The area to be scanned falls within the orthographic projection of the n sub-scanning areas. The calculation formula of n is: ； S4, scanning the n sub-scanning areas in sequence along the length direction of the groove using a three-dimensional laser scanner to obtain n groups of point cloud data, each group of the point cloud data includes spatial three-dimensional coordinates, and each group of the point cloud data corresponds to one sub-scanning area; S5. Using the point cloud data of the common marking points of two adjacent sub-scanning areas as a reference, using Geomagic software to splice the point cloud data of the n sub-scanning areas to obtain complete point cloud data of the groove; S6. A three-dimensional groove model is established according to the complete point cloud data of the groove, and the instantaneous cross-sectional area of ​​the groove is calculated using Geomagic software. According to the instantaneous cutting resistance on the cutting path collected in step S1 and the instantaneous cross-sectional area of ​​the groove, the instantaneous rock breaking specific energy on the cutting path is calculated. The calculation formula of the instantaneous rock breaking specific energy is: ； In formula (2): SE( t ) is the instantaneous rock breaking specific energy, in J / m 3 ; F r ( t ) is the instantaneous cutting resistance on the cutting path, in N; is the instantaneous cutting speed, in m / s; A ( t ) is the instantaneous cross-sectional area of ​​the groove, in m 2 ; t is the cutting time of the groove.

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