Rock strength rapid prediction method

Abstract

The invention discloses a rapid prediction method for rock strength. The rapid prediction method comprises the following steps: 1, collecting various types of rock samples; 2, determining a tool type and tool control parameters; 3, cutting the rock sample by using the vertical cutting test bed and collecting a cutting normal force generated by cutting the rock sample each time; 4, carrying out a uniaxial compression test and a Brazilian splitting test to obtain uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock; 5, fitting a rock strength prediction function based on the cutting normal force; 6, replacing the type of the cutter, adjusting the cutter control parameters of the corresponding cutter, and obtaining a new rock strength prediction function; 7, acquiring corresponding rock strength prediction functions of different tool types under the condition of corresponding tool control parameters; and 8, quickly predicting the rock strength on site. Related tests are carried out, a prediction function of the rock strength and the cutting load is established, the rock strength can be rapidly and accurately predicted by using the prediction function, and the field rock strength test is effective.

Description

Technical Field

[0001] The invention belongs to the technical field of rock strength prediction, and in particular relates to a method for quickly predicting rock strength. Background Art

[0002] Strength is the most important mechanical property index of rock, and uniaxial compressive strength and splitting tensile strength are the most commonly used. In mechanized tunnel excavation construction, it is necessary to quickly obtain the strength of different surrounding rocks to match the operating parameters of the equipment; in indoor research, it is often necessary to collect and prepare rock samples of different strengths to carry out specific tests. The most common and reliable methods for testing rock strength are uniaxial compression and Brazilian splitting tests, which require special large-scale test equipment, strict test process requirements, high sample preparation accuracy requirements, and long test cycles. At the same time, rock sample preparation and loading need to be carried out in accordance with the corresponding standards. The obtained rock strength results are the most accurate and reliable, and multiple mechanical property parameters such as Young's modulus and Poisson's ratio can be obtained at the same time. However, due to the limited test conditions at the engineering site and rock mine, it is not easy to quickly and accurately obtain rock strength; in addition, there are also functions such as image recognition and deep learning for rock strength prediction, which require the environment where the rock is located and the rock itself to have corresponding image acquisition applicable conditions, low on-site application efficiency, and improper sample collection and processing will result in large errors. Therefore, there is an urgent need for a rapid prediction method for rock strength. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for quickly predicting rock strength in view of the deficiencies in the above-mentioned prior art. By carrying out relevant experiments, a prediction function of rock strength and cutting load is established. It can be seen that the normal load is positively correlated with the rock strength. The prediction function can be used to quickly and accurately predict the rock strength, providing an effective means for rock strength testing in on-site construction, which is convenient for promotion and use.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for rapid prediction of rock strength, characterized in that the method comprises the following steps:

[0005] Step 1: Collect various types of rock samples;

[0006] Step 2, determine the tool type and tool control parameters: the tool types include hobs, pick cutters and ball cutters, and the tool control parameters include penetration, cutting speed and cutter spacing;

[0007] Step 3, using a vertical cutting test bench to cut rock samples and collect the cutting normal force generated each time the rock samples are cut: the vertical cutting test bench includes a vertical cutting mechanism and a two-axis sliding platform coordinated with the vertical cutting mechanism, the vertical cutting mechanism includes a frame and a tool slide rail and a hydraulic cylinder vertically mounted on the frame, the tool slide rail and the hydraulic cylinder are mounted on the frame in a parallel structure, the hydraulic cylinder is located on the outside of the tool slide rail, a tool slider is slidably arranged on the tool slide rail, an F-shaped tool holder fixing block is fixedly arranged on the outer surface of the tool slider, the top of the tool holder fixing block is connected to the telescopic end of the plunger rod of the hydraulic cylinder, a tool holder is fixedly mounted on the tool holder fixing block, a tool holder is mounted on the tool holder, a tool head for cutting rock samples and a three-axis force sensor for collecting the cutting normal force generated each time the rock samples are cut are mounted on the tool holder;

[0008] Step 4: Carry out uniaxial compression test and Brazilian splitting test for each type of test of each type of rock collected, and obtain the uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock, wherein the uniaxial compression test and Brazilian splitting test for each type of test of each type of rock shall be no less than 3 times;

[0009] Step 5: Fitting rock strength prediction function based on cutting normal force: The rock strength prediction function includes uniaxial compressive strength function and splitting tensile strength function. The uniaxial compressive strength function and splitting tensile strength function are fitted respectively using the uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock and the cutting normal force generated by each cutting of the rock sample. Among them, σ c is the uniaxial compressive strength value, F N is the cutting normal force, b is the first-order fitting coefficient of the uniaxial compressive strength function, a is the constant fitting coefficient of the uniaxial compressive strength function, σ t is the splitting tensile strength value, d is the first-order fitting coefficient of the splitting tensile strength function, and c is the constant fitting coefficient of the splitting tensile strength function;

[0010] Step 6: Change the tool type and adjust the tool control parameters of the corresponding tool, repeat steps 3 to 5, and obtain the rock strength prediction function corresponding to the changed tool type;

[0011] Step 7, repeating step 6 multiple times to obtain corresponding rock strength prediction functions of various tool types under corresponding tool control parameter conditions;

[0012] Step 8: Rapidly predict rock strength on site: select the tool type and determine the tool control parameters, use the vertical cutting test bench to cut the rock on site and collect the cutting normal force generated by each rock cutting, and quickly obtain the rock strength prediction value based on the corresponding uniaxial compressive strength function and splitting tensile strength function.

[0013] The above-mentioned method for rapid prediction of rock strength is characterized in that: in step 1, the lithology, structure and strength of the multiple types of rock samples are different.

[0014] The above-mentioned method for rapid prediction of rock strength is characterized in that: in step three, a process of cutting rock samples using a vertical cutting test bench and collecting the cutting normal force generated by each cutting of the rock samples is carried out: a tool linear cutting test is carried out on each batch of rocks, the penetration, cutting speed and tool spacing are set, and no less than 3 groups of solitary cutting tests are automatically and continuously carried out on the surface to be cut of a piece of rock, and the data obtained from no less than 3 groups of solitary cutting tests are denoised and the average is taken.

[0015] The above-mentioned method for rapid prediction of rock strength is characterized in that: in step 4, the uniaxial compression test and Brazilian splitting test of each type of test for each type of rock are carried out no less than 3 times, and the data obtained from the uniaxial compression test and Brazilian splitting test of each type of test for each type of rock no less than 3 times are denoised and the average is taken.

[0016] The above-mentioned method for rapid prediction of rock strength is characterized in that: in step five, the uniaxial compressive strength function and the splitting tensile strength function are fitted using the denoised mean data.

[0017] The above-mentioned method for rapid prediction of rock strength is characterized in that the two-axis sliding platform is a horizontal and vertical two-axis sliding platform, which is used to drive the rock sample to move, thereby controlling the penetration rate and movement of the rock sample.

[0018] The beneficial effects of the present invention are that the tool advancement is controlled by the vertical cutting mechanism, and the hydraulic cylinder and the plunger rod carry the tool slide rail to make an up and down reciprocating feed motion, thereby driving the tool holder to cut the rock, matching the movement of the two-axis sliding platform, supporting a variety of tools, meeting the needs of various types of tool rock breaking mechanism and wear performance test research, and being easy to move. By carrying out relevant experiments, a prediction function of rock strength and cutting load is established, and it can be seen that the normal load is positively correlated with the rock strength. The prediction function can be used to quickly and accurately predict the rock strength, providing an effective means for rock strength testing in on-site construction, which is convenient for popularization and use.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the vertical cutting test bench of the present invention.

[0021] Figure 2 It is a structural schematic diagram of the vertical cutting mechanism of the present invention.

[0022] Figure 3It is a flowchart of the method of the present invention.

[0023] Description of reference numerals:

[0024] 1—machine frame; 2—tool slide rail; 3—tool slide block;

[0025] 4—tool holder fixing block; 5—plunger rod; 6—hydraulic cylinder;

[0026] 7—knife holder; 701—knife seat; 702—knife head;

[0027] 8—three-axis force sensor; 9—rock sample; 10—two-axis sliding platform. DETAILED DESCRIPTION

[0028] like Figures 1 to 3 As shown, a rock strength rapid prediction method of the present invention comprises the following steps:

[0029] Step 1: Collect various types of rock samples;

[0030] Step 2, determine the tool type and tool control parameters: the tool types include hobs, pick cutters and ball cutters, and the tool control parameters include penetration, cutting speed and cutter spacing;

[0031] Step 3, using a vertical cutting test bench to cut rock samples and collect the cutting normal force generated each time the rock samples are cut: the vertical cutting test bench includes a vertical cutting mechanism and a two-axis sliding platform 10 coordinated with the vertical cutting mechanism, the vertical cutting mechanism includes a frame 1 and a tool slide 2 and a hydraulic cylinder 6 vertically mounted on the frame 1, the tool slide 2 and the hydraulic cylinder 6 are mounted on the frame 1 in a parallel structure, the hydraulic cylinder 6 is located on the outside of the tool slide 2, a tool slider 3 is slidably arranged on the tool slide 2, an F-shaped tool holder fixing block 4 is fixedly arranged on the outer surface of the tool slider 3, the top of the tool holder fixing block 4 is connected to the telescopic end of the plunger rod 5 of the hydraulic cylinder 6, a tool holder 7 is fixedly installed on the tool holder fixing block 4, a tool holder 7 is installed on the tool holder 7, a tool seat 701 is installed on the tool seat 701, a tool head 702 for cutting rock samples 9 and a three-axis force sensor 8 for collecting the cutting normal force generated each time the rock samples are cut are installed on the tool seat 701;

[0032] In actual implementation, the rock sample 9 is first fixed on the two-axis sliding platform 10 and does not move. Then, a cutting depth is pre-adjusted through the two-axis sliding platform 10. Then, the plunger rod 5, pushed by the hydraulic cylinder, drives the cutter head to complete a straight line cutting experiment. After completion, the plunger rod 5 is retracted. At this time, the two-axis sliding platform 10 drives the rock sample 9 to move horizontally, and then the next experiment is carried out in sequence. If the cutting depth needs to be adjusted, the two-axis sliding platform 10 can also be readjusted.

[0033] Step 4: Carry out uniaxial compression test and Brazilian splitting test for each type of test of each type of rock collected, and obtain the uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock, wherein the uniaxial compression test and Brazilian splitting test for each type of test of each type of rock shall be no less than 3 times;

[0034] Step 5: Fitting rock strength prediction function based on cutting normal force: The rock strength prediction function includes uniaxial compressive strength function and splitting tensile strength function. The uniaxial compressive strength function and splitting tensile strength function are fitted respectively using the uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock and the cutting normal force generated by each cutting of the rock sample. Among them, σ c is the uniaxial compressive strength value, F N is the cutting normal force, b is the first-order fitting coefficient of the uniaxial compressive strength function, a is the constant fitting coefficient of the uniaxial compressive strength function, σ t is the splitting tensile strength value, d is the first-order fitting coefficient of the splitting tensile strength function, and c is the constant fitting coefficient of the splitting tensile strength function;

[0035] Step 6: Change the tool type and adjust the tool control parameters of the corresponding tool, repeat steps 3 to 5, and obtain the rock strength prediction function corresponding to the changed tool type;

[0036] Step 7, repeating step 6 multiple times to obtain corresponding rock strength prediction functions of various tool types under corresponding tool control parameter conditions;

[0037] Step 8: Rapidly predict rock strength on site: select the tool type and determine the tool control parameters, use the vertical cutting test bench to cut the rock on site and collect the cutting normal force generated by each rock cutting, and quickly obtain the rock strength prediction value based on the corresponding uniaxial compressive strength function and splitting tensile strength function.

[0038] It should be noted that the tool advancement is controlled by the vertical cutting mechanism, and the hydraulic cylinder and plunger rod carry the tool slide rail to make up and down reciprocating feed motion, thereby driving the tool holder to cut the rock. It matches the movement of the two-axis sliding platform, supports a variety of tools, and meets the needs of experimental research on rock breaking mechanism and wear performance of various types of tools. It is convenient to move. Through relevant experiments, a prediction function of rock strength and cutting load is established. It can be seen that the normal load is positively correlated with the rock strength. The prediction function can be used to quickly and accurately predict the rock strength, providing an effective means for rock strength testing in on-site construction.

[0039] In this embodiment, in step 1, the lithology, structure and strength of the multiple types of rock samples are different.

[0040] In this embodiment, in step three, a process of cutting rock samples using a vertical cutting test bench and collecting the cutting normal force generated each time the rock samples are cut is performed: a tool linear cutting test is performed on each batch of rock, the penetration, cutting speed and tool spacing are set, and no less than 3 groups of solitary cutting tests are automatically and continuously carried out on the surface of a rock to be cut, and the data obtained from no less than 3 groups of solitary cutting tests are denoised and the average is taken.

[0041] In this embodiment, in step 4, the uniaxial compression test and Brazilian splitting test of each type of test for each type of rock are performed no less than 3 times, and the data obtained from the uniaxial compression test and Brazilian splitting test of each type of test for each type of rock no less than 3 times are denoised and the average is taken.

[0042] In this embodiment, in step five, the uniaxial compressive strength function and the splitting tensile strength function are fitted using the denoised mean data.

[0043] In this embodiment, the two-axis sliding platform 10 is a horizontal and vertical two-axis sliding platform, which is used to drive the rock sample 9 to move, thereby controlling the penetration degree of the rock sample 9 and the movement of the rock sample 9.

[0044] In this embodiment, the tool type takes a 1.2mm roller as an example, and a tool linear cutting test is carried out on each batch of rocks. The penetration is set to be fixed at 2mm, and the cutting speed is controlled to 10mm / s. Each group of tests is a single roller isolated cutting, that is, it cannot be affected by the mutual influence of adjacent track cutting. Therefore, the spacing between adjacent cutting tracks is set to be no less than 50mm. On the surface to be cut of a rock, no less than 3 groups of isolated cutting tests are automatically and continuously carried out. Among them, the penetration is set to 2mm. First, the small-scale roller linear cutting test bench used is flexible and convenient, but due to the small size and many bonding interfaces of key components and assemblies such as rollers, cutter shafts, bearings, tool boxes and three-way force sensors, the guide As a result, its rigidity is limited. When cutting high-hard rock with a uniaxial compressive strength of more than 160MPa, when the penetration is greater than 3mm, the peak load of the hob load is close to or even exceeds 15kN, and the compression deformation of the cutting module is large, resulting in the actual penetration being significantly less than the set penetration. At the same time, the frequency of hob edge rolling, chipping and bearing damage increases significantly. In order to fully consider the cutting characteristics of rocks of various strengths, it is recommended to set the penetration to no more than 2mm; secondly, when the set penetration is less than 1mm, the cutting result is greatly affected by the surface flatness, parallelism and penetration adjustment error of the sample, and most of the time only one indentation appears on the hard rock surface without entering the fracture stage, so the penetration is preferably 2mm.

[0045] In this embodiment, the uniaxial compressive strength and splitting tensile strength corresponding to each type of rock test and the cutting normal force generated by each cutting of the rock sample are used to fit the uniaxial compressive strength function and the splitting tensile strength function.

[0046] When the present invention is used, a vertical linear cutting table is used to directly perform linear cutting on the rock surface without pre-cutting the rock surface. The vertical linear cutting table has low cost, is easy to manufacture, flexible and convenient, and produces reliable results. The normal force is obtained by linear cutting, and the normal force data is substituted into the constructed prediction function to obtain the predicted values ​​of the uniaxial compressive strength and splitting tensile strength of the rock.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for rapid prediction of rock strength, characterized in that: The method comprises the following steps: Step 1: Collect various types of rock samples; Step 2, determine the tool type and tool control parameters: the tool types include hobs, pick cutters and ball cutters, and the tool control parameters include penetration, cutting speed and cutter spacing; Step 3: Cut rock samples using a vertical cutting test bench and collect the cutting normal force generated by each cutting of the rock samples: the vertical cutting test bench comprises a vertical cutting mechanism and a two-axis sliding platform (10) coordinated with the vertical cutting mechanism, the vertical cutting mechanism comprises a frame (1) and a tool slide rail (2) and a hydraulic cylinder (6) vertically mounted on the frame (1), the tool slide rail (2) and the hydraulic cylinder (6) are mounted on the frame (1) in a parallel structure, the hydraulic cylinder (6) is located on the outside of the tool slide rail (2), and the tool slide rail ( 2) a tool slide block (3) is slidably arranged on the upper side, an F-shaped tool holder fixing block (4) is fixedly arranged on the outer side surface of the tool slide block (3), the top of the tool holder fixing block (4) is connected to the telescopic end of the plunger rod (5) of the hydraulic cylinder (6), a tool holder (7) is fixedly installed on the tool holder fixing block (4), a tool holder (701) is installed on the tool holder (7), and a tool head (702) for cutting a rock sample (9) and a three-axis force sensor (8) for collecting a cutting normal force generated by each cutting of the rock sample are installed on the tool holder (701); Step 4: Carry out uniaxial compression test and Brazilian splitting test for each type of test of each type of rock collected, and obtain the uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock, wherein the uniaxial compression test and Brazilian splitting test for each type of test of each type of rock shall be no less than 3 times; Step 5: Fitting rock strength prediction function based on cutting normal force: The rock strength prediction function includes uniaxial compressive strength function and splitting tensile strength function. The uniaxial compressive strength function and splitting tensile strength function are fitted respectively using the uniaxial compressive strength and splitting tensile strength corresponding to each type of test of each type of rock and the cutting normal force generated by each cutting of the rock sample. Among them, σ c is the uniaxial compressive strength value, F N is the cutting normal force, b is the first-order fitting coefficient of the uniaxial compressive strength function, a is the constant fitting coefficient of the uniaxial compressive strength function, σ t is the splitting tensile strength value, d is the first-order fitting coefficient of the splitting tensile strength function, and c is the constant fitting coefficient of the splitting tensile strength function; Step 6: Change the tool type and adjust the tool control parameters of the corresponding tool, repeat steps 3 to 5, and obtain the rock strength prediction function corresponding to the changed tool type; Step 7, repeating step 6 multiple times to obtain corresponding rock strength prediction functions of various tool types under corresponding tool control parameter conditions; Step 8: Rapidly predict rock strength on site: select the tool type and determine the tool control parameters, use the vertical cutting test bench to cut the rock on site and collect the cutting normal force generated by each rock cutting, and quickly obtain the rock strength prediction value based on the corresponding uniaxial compressive strength function and splitting tensile strength function.

2. A rock strength rapid prediction method according to claim 1, characterized in that: In step one, the lithology, structure and strength of the multiple types of rock samples are different.

3. A rock strength rapid prediction method according to claim 1, characterized in that: In step three, a vertical cutting test bench is used to cut rock samples and collect the cutting normal force generated each time the rock samples are cut: a straight-line cutting test of the tool is performed on each batch of rock, the penetration, cutting speed and tool spacing are set, and no less than 3 groups of solitary cutting tests are automatically and continuously carried out on the surface of a rock to be cut. The data obtained from no less than 3 groups of solitary cutting tests are denoised and the average is taken.

4. A rock strength rapid prediction method according to claim 3, characterized in that: In step 4, the uniaxial compression test and Brazilian splitting test of each type of test for each type of rock are conducted at least 3 times, and the data obtained from the uniaxial compression test and Brazilian splitting test of each type of test for each type of rock at least 3 times are denoised and the average is taken.

5. A rock strength rapid prediction method according to claim 4, characterized in that: In step five, the uniaxial compressive strength function and the splitting tensile strength function are fitted using the denoised mean data.

6. A rock strength rapid prediction method according to claim 1, characterized in that: The two-axis sliding platform (10) is a horizontal and vertical two-axis sliding platform, which is used to drive the rock sample (9) to move, thereby controlling the penetration of the rock sample (9) and the movement of the rock sample (9).

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