An in-situ evaluation method for rock mass mechanical parameters and engineering characteristics

Abstract

The present invention discloses an in-situ evaluation method for rock mass mechanical parameters and engineering characteristics. By conducting mechanical rock breaking tests on the rock mass at the engineering site, dividing the rock mass cuttability zones according to the characterization parameters of the rock breaking effect, establishing the relationship between the scratch axial load and the rock mass mechanical parameters with the help of indoor rock mass mechanical tests and rock scratch tests, obtaining the scratch axial load zoning threshold for evaluating the rock mass cuttability, providing a theoretical basis for the visual zoning evaluation of the rock mass cuttability, promising to achieve the advanced acquisition of rock mass mechanical parameters under in-situ conditions, quantifying the evaluation index and evaluation process of the rock mass cuttability, which can be used to guide the early perception of the changes in rock mass mechanical parameters during the construction of rock mass engineering, accurately identify and locate the rock mass in front of the difficult-to-cut area in mechanical rock breaking practice, and then implement targeted mutagenesis modification measures on the rock mass or select appropriate rock breaking equipment and parameters to improve the mechanical rock breaking efficiency and reduce the rock breaking cost.

Description

Technical Field

[0001] The present invention relates to the technical field of rock mechanics and engineering, and particularly to an in-situ evaluation method for rock mechanics parameters and engineering characteristics. Background Art

[0002] How to achieve in-situ and advanced perception of rock mechanics parameters has always been the core topic in the field of rock mechanics research. The traditional method of obtaining rock mechanics parameters through laboratory tests is cumbersome, costly, and unable to test the properties of rocks in real-time and in-situ under actual construction environmental conditions. Therefore, the current evaluation of the mechanical and engineering characteristics of in-situ rocks mainly relies on qualitative evaluation, the evaluation process is more empirical, and there is a lag in the optimization of construction parameters.

[0003] The lack of an in-situ evaluation system for obtaining rock mechanics parameters and the cuttability of rocks based on quantitative indicators is also the key restricting the practice of non-explosive mechanized rock breaking technology in hard rocks. Currently, the fragmentation of hard rock ore bodies generally uses the drill and blast method. Compared with mechanized construction, the drill and blast method has disadvantages such as large induced damage, discontinuity, and low efficiency. The strong disturbance generated by blasting is also prone to induce rockburst and other rock dynamic disasters in the deep environment, posing potential safety hazards to construction. If an in-situ and advanced evaluation of the cuttability of rocks can be achieved, targeted modification measures can be taken for hard rocks in difficult-to-cut areas before non-explosive mechanized excavation, improving the cuttability of rocks, and then achieving efficient, non-explosive, and continuous fragmentation of hard rocks. Summary of the Invention

[0004] The present invention provides an in-situ evaluation method for rock mechanics parameters and engineering characteristics. By establishing the relationship between scratch data and rock mechanics parameters through the hole wall scratch penetration test, in-situ and advanced acquisition of rock mechanics parameters is achieved, and further evaluation of the change in the cuttability of rocks is carried out to guide the precise modification of rocks in difficult-to-cut areas in advance during the practice of non-explosive mechanized rock breaking, making the cuttability of rocks adapt to the requirements of mechanical rock breaking and improving the efficiency of mechanized rock breaking.

[0005] An in-situ evaluation method for rock mechanics parameters and engineering characteristics provided by the present invention includes the following steps:

[0006] S1. Through on-site mechanical rock breaking tests, collect the characterization parameters of rock breaking effects under different lithological environmental conditions, and conduct zoning of the cuttability of rocks for the rocks at different construction test sites.

[0007] S2. Take samples from the construction test sites, obtain the rock mechanics parameters of rocks under different lithological environments through laboratory rock mechanics tests, conduct indoor rock scratch tests on the sampled rocks, fit the scratch axial load - rock mechanics parameter curves at different scratch depths, obtain the best fitting model, and determine the optimal test scratch depth.

[0008] S3. Partition the best-fit model according to the rock mass cuttability zones determined in step S1 to determine the threshold values for the axial load zones of the scratch marks.

[0009] S4. Drill holes in the rock mass of the tunnel face from shallow to deep, and carry out scratch penetration tests on the rock mass of the hole wall at the optimal test scratch depth to obtain the data of the axial load of the scratch marks varying with the hole depth.

[0010] S5. Through the layout of the drill hole array and the collection of scratch test data, use the threshold values of the axial load zones of the scratch marks to construct a cloud map for characterizing the cuttability of the rock mass in front of the tunnel face, so as to accurately guide the modification of the difficult-to-cut areas of the rock mass in front, improve the cuttability of the rock mass and the efficiency of non-explosive mechanical rock breaking. At the same time, the rock mass mechanical parameters and their variation conditions of the rock mass in front of the tunnel face can also be back-calculated by using the best-fit model.

[0011] As a further improvement of the present invention, in step S1, the construction method of the rock mass cuttability zones is as follows:

[0012] Carry out a series of on-site mechanical rock breaking tests under different lithological environment conditions and the same operating state of the rock breaking machinery. Take the rock breaking efficiency (the mass of broken rock per hour on average, t / h) and the cutter head loss (the number of cutter heads consumed per 1 t of broken rock on average, pieces / t) as the characterization indexes of the rock breaking effect. Among them, determine one point for the rock mass at the same construction site, construct a scatter plot of the cutter head loss - rock breaking efficiency, and take the average rock breaking efficiency Average cutter head loss As the characterization threshold value, conduct the partition of the rock mass cuttability zones: easy-to-mining area (the rock breaking efficiency is greater than and the cutter head loss is less than ); difficult-to-mining area (the rock breaking efficiency is less than and the cutter head loss is less than the rock breaking efficiency is greater than and the cutter head loss is greater than ); extremely difficult-to-mining area (the rock breaking efficiency is less than and the cutter head loss is greater than ).

[0013] As a further improvement of the present invention, the method for obtaining the best-fit model through indoor rock scratch tests is as follows:

[0014] SS1. Drill rock cores at the rock breaking test site under different lithological environments, and process the rock cores into standard specimens.

[0015] SS2. Carry out indoor rock mass mechanical tests to obtain the rock mass mechanical parameters of the specimens at each sampling point.

[0016] SS3. Set a series of scratch depths and conduct indoor rock scratch tests: Keep the scratch depth fixed, obtain the scratch axial loads of different specimens, and create scatter plots of scratch axial load - rock mass mechanical parameters at a series of scratch depths.

[0017] SS4. Fit the relationship curve and equation of scratch axial load - rock mass mechanical parameters, compare the determination coefficients of each fitting result to obtain the best fitting model, and the scratch depth corresponding to this model is the optimal test scratch depth.

[0018] The core samples are drilled from the same mother rock on the tunnel face of the corresponding construction site to ensure that the processed standard specimens have almost the same physical and mechanical properties.

[0019] The rock mass mechanical parameters can be selected as the peak rock-breaking load, uniaxial / triaxial compressive strength of the rock, tensile strength, elastic modulus, etc.

[0020] The setting of the scratch depth needs to be less than the minimum peak indentation depth of the specimens at each sampling point. Taking 0.05 mm as the progressive unit, the minimum peak indentation depth is used as the maximum value to set the series of scratch depth gradients.

[0021] The scatter points in the scatter plots of scratch axial load - rock mass mechanical parameters represent the characteristic points of rock mass specimens at different construction sites, and the scratch axial load obtained through the rock scratch test is the average load during the scratch process.

[0022] The relationship curve, equation, and determination coefficient of scratch axial load - rock mass mechanical parameters can be obtained by fitting with common plotting software such as Origin and MATLAB.

[0023] As a further improvement of the present invention, there are two methods for determining the scratch axial load partition threshold:

[0024] (1) According to the characteristics of rock mass cuttability zoning, select the average value of the rock mass mechanical parameters of two adjacent specimen points in two adjacent partitions on the best fitting model as the critical threshold, and obtain the scratch axial load partition threshold corresponding to the fitting curve.

[0025] (2) According to the characteristics of rock mass cuttability zoning, select the average value of the scratch axial loads of two adjacent specimen points in two adjacent partitions on the best fitting model as the scratch axial load partition threshold.

[0026] As a further improvement of the present invention, the operating steps of the scratch penetration test on the hole wall rock mass are as follows:

[0027] Drill holes at the construction face, assemble the hole wall scratch penetration device onto the drill pipe of the drilling jumbo, adjust and fix the scratch depth to the optimal test scratch depth, and conduct the hole wall scratch penetration test in the drill hole from shallow to deep. Record and transmit the data of the scratch axial load varying with the hole depth through the axial load sensor to the big data analysis and processing platform.

[0028] As a further improvement of the present invention, the hole wall scratch penetration device is composed of an adapter, a transmission rod, transmission teeth, a conical head, an annular sleeve, a gear, a motor, a servo electric cylinder, and a pick. Among them, the adapter can connect the drill pipe and the transmission rod through the grooves at both ends. The bottom of the transmission rod is provided with transmission teeth extending along the length direction of the transmission rod. A conical head is installed at the other end of the transmission rod. The annular sleeve is sleeved on the transmission rod and can move freely. A gear is installed on the bottom surface of the annular sleeve, and the gear meshes with the transmission teeth. The motor arranged on the outside provides power for the transmission of the gear. A servo electric cylinder is installed below the gear, and the end face of the telescopic lead screw of the servo electric cylinder is connected to the pick.

[0029] As a further improvement of the present invention, according to the evaluation of the cuttability zoning characterization of the rock mass in front of the face, targeted rock mass modification measures are taken for different difficult-to-mine areas, including: for the difficult-to-mine area, increase the free surface of the rock mass by constructing a pressure relief groove in the difficult-to-mine area to improve the cuttability of the rock mass in the difficult-to-mine area; for the extremely difficult-to-mine area, first construct hydraulic fracturing drill holes, and then conduct hydraulic fracturing through the fracturing equipment to promote the generation of new cracks and the expansion of primary fractures in the rock mass, thereby reducing the integrity of the rock mass and deteriorating the physical and mechanical properties of the rock mass to achieve the purpose of improving the cuttability of the rock mass.

[0030] The beneficial effects of the present invention:

[0031] (1) Realize the in-situ and advanced acquisition of rock mass mechanical parameters. The present invention establishes the connection between the on-site monitoring data of the hole wall scratch and the rock mass mechanical parameters through hole wall penetration, realizes the real-time, continuous, and accurate perception of the mechanical parameters of the rock mass in front, and breaks through the limitations of non-in-situ, non-continuous, and complex processes in obtaining rock mass mechanical parameters by traditional laboratory tests.

[0032] (2) Provide an in-situ evaluation method for the cuttability of rock mass. The present invention correlates the scratch axial load with the cuttability of the rock mass, combines the on-site rock breaking effect with the parameters of the indoor scratch test, obtains the scratch axial load zoning threshold, and realizes the zoning visualization characterization of the cuttability of the rock mass in front under in-situ conditions.

[0033] (3) Guide the targeted modification of the rock mass in difficult cutting areas to improve the mechanical rock breaking efficiency. By arranging a hole array on the construction face, scratch test data under in-situ conditions are obtained to achieve three-dimensional visualization of the cutability of the rock mass, providing a quantitative basis for accurately positioning and demarcating difficult mining areas during on-site construction. Furthermore, it guides the construction party to take targeted modification measures for the rock mass in difficult mining areas, reducing the difficulty of rock cutting, reducing the consumption of cutting heads, and improving the mechanical rock breaking efficiency.

[0034] (4) The on-site dynamic rock breaking practice and the assessment of rock mass cutability can be jointly carried out in real time to realize the optimization regulation of the operation process of rock breaking machinery and the in-situ optimization characterization of rock mass cutability. Based on the real-time data obtained from on-site rock breaking (such as the change in rock breaking load during the rock breaking process of the cutting head), the operation attitude of the rock breaking machinery is feedback-regulated through a big data analysis and processing platform to ensure the best rock breaking effect. For the rock mass area where the cutting load during the cutting head rock breaking process significantly increases and the fuselage shakes violently, it is initially regarded as a difficult / extremely difficult mining area, and an in-situ assessment method is adopted for this area to obtain the mechanical parameters of the rock mass ahead and evaluate the distribution of rock mass cutability. For the area where there is no obvious change in the cutting load during mechanical rock breaking construction and the mechanical operation is stable, in-situ assessment is not necessary, thus saving the huge cost caused by all-round assessment and promoting the intelligent development of the mechanical rock breaking process. Description of the Drawings

[0035] Figure 1 Schematic diagram of the zoning of rock mass cutability based on rock breaking effect characterization parameters;

[0036] Figure 2 Schematic diagram of the fitting of scratch axial load - peak rock breaking load at a specific scratch depth;

[0037] Figure 3 Schematic diagram of the in-situ scratch penetration test of the rock mass on the hole wall;

[0038] Figure 4 Schematic diagram of the structure of the scratch penetration device;

[0039] Figure 5 Schematic diagram of the zonal characterization of the data of the in-situ scratch penetration test on the hole wall changing with the hole depth;

[0040] Figure 6 Schematic diagram of guiding non-explosive mechanized rock breaking practice;

[0041] The marks and corresponding names in the drawings are as follows:

[0042] 1. Tunnel face rock mass; 2. Drilling jumbo; 201. Propelling beam; 202. Rock drill; 203. Front seat; 204. Telescopic oil cylinder; 3. Drill pipe; 4. Hole wall scratch sounding device; 401. Adapter; 402. Transmission rod; 403. Transmission gear; 404. Tapered head; 405. Ring sleeve; 406. Gear; 407. Motor; 408. Servo electric cylinder; 409. Pick; 5. Roadheader; 501. Cutting unit; 502. Machine body; 503. Traveling unit; 504. Loading apron; 505. Rear support unit; 506. First conveyor; 6. Big data analysis and processing platform; 7. Hydraulic fracturing borehole; 8. Pressure relief groove. Detailed implementation manners

[0043] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0045] An in-situ evaluation method for rock mass mechanical parameters and engineering characteristics provided by an embodiment of the present invention includes the following steps:

[0046] S1. Through on-site mechanical rock breaking tests, collect the rock breaking effect characterization parameters under different lithological environment conditions, and conduct rock mass cuttability zoning for the rock masses at different construction test sites;

[0047] Carry out a series of on-site mechanical rock breaking tests under different lithological environment conditions and the same operating state of the rock breaking machine. For example, Figure 1 , taking the rock breaking efficiency (the mass of broken rock per hour on average, t / h) and the cutting head loss (the number of cutting heads consumed per 1 t of broken rock on average, pieces / t) as the rock breaking effect characterization indexes. Among them, determine one point for the rock mass at the same construction site, construct a scatter plot of cutting head loss - rock breaking efficiency, and take the average rock breaking efficiency Average cutting head loss as the characterization threshold to conduct rock mass cuttability zoning: Easy mining area (rock breaking efficiency is greater than and the cutting head loss is less than ); Difficult mining area (rock breaking efficiency is less than and the cutting head loss is less than ; Rock breaking efficiency is greater than and the cutting head loss is greater than ); Extremely difficult mining area (rock breaking efficiency is less than and the cutting head loss is greater than ).

[0048] S2. Take samples from the construction test site and obtain the rock mass mechanical parameters of the rock mass in different lithological environments through indoor rock mass mechanical tests. Conduct indoor rock scratch tests on the sampled rock mass, fit the scratch axial load - rock mass mechanical parameter curves at different scratch depths, obtain the best fitting model, and determine the optimal test scratch depth;

[0049] The rock mass mechanical parameters can be selected as the peak rock-breaking load, uniaxial / triaxial compressive strength of the rock, tensile strength, elastic modulus, etc. The above-listed peak rock-breaking load, uniaxial / triaxial compressive strength, tensile strength, elastic modulus, etc. are all typical traditional rock mass mechanical parameters. The peak rock-breaking load can be obtained through rock-breaking tests, the uniaxial compressive strength can be obtained through rock uniaxial compression tests, the triaxial compressive strength can be obtained through true triaxial rock tests, the tensile strength can be obtained through Brazilian splitting tests, and the elastic modulus can be obtained synchronously through uniaxial compression tests.

[0050] The scratch axial load is data that can be obtained from in-situ tests, and the peak rock-breaking load is the most critical index during the rock-breaking process. Since both are loads, the degree of correlation between the two is higher than that of others. Therefore, in this embodiment, the construction of the correlation between the scratch axial load and the peak rock-breaking load is taken as an example for illustration. Of course, the correlation between the scratch axial load and other rock mass mechanical parameters can also be constructed.

[0051] Therefore, step S2 can be specifically: Take samples from the construction site and obtain the peak rock-breaking load of the rock mass in different lithological environments through indoor rock-breaking tests. Conduct indoor rock scratch tests on the sampled rock mass, fit the scratch axial load - peak rock-breaking load curves at different scratch depths, obtain the best fitting model, and determine the optimal test scratch depth;

[0052] The method for determining the best fitting model is:

[0053] SS1. Drill cores at the rock-breaking test sites (the sites in step S1) in different lithological environments and process the cores into standard specimens;

[0054] The cores are drilled from the same piece of parent rock on the working face of the corresponding construction site to ensure that the processed standard specimens have almost the same physical and mechanical properties.

[0055] SS2. Conduct indoor rock-breaking tests to obtain the peak rock-breaking load and peak indentation depth of the specimens at each sampling point in different construction test sites;

[0056] During the rock breaking test, rock breaking tools (pick-shaped picks, bucket teeth, and disc cutters) are selected according to the cutting head characteristics of the rock breaking machinery at the construction test site. Taking the rock breaking by a roadheader at the site as an example, a pick-shaped pick intrusion rock breaking test is carried out in the laboratory correspondingly. The pick-shaped pick is installed on the Z-direction loading mechanism of the rock breaking test system, and a cutting load is applied to the upper surface of the specimen through the Z-direction loading mechanism to simulate the process of the pick invading the rock at the site, and the changes in the pick load and the pick intrusion depth are recorded. The load corresponding to the specimen breaking is the peak rock breaking load, and the corresponding pick intrusion depth is the peak indentation depth.

[0057] SS3. Set a series of scratch depths, and conduct indoor rock scratch tests on the specimens at each sampling point in different construction test sites. A continuous scratch test system is used, which consists of a dynamic loading module, a displacement / load measurement module, a tool, a specimen fixture, and a data acquisition and analysis system, and can record the change in the axial load of the tool during scratching at a fixed scratch depth in real time. Keeping the scratch depth unchanged, the scratch axial loads of different specimens are obtained, and a scatter plot of scratch axial load - peak rock breaking load is made under a series of scratch depths;

[0058] Since the limit of the scratch depth is only related to the peak indentation depth of rock breaking, and the rock will break when this depth is reached, therefore, the scratch depth needs to be set less than the minimum peak indentation depth of the specimens at each sampling point, with a progression unit of 0.05 mm, and the minimum peak indentation depth is used as the maximum value to set a series of scratch depth gradients.

[0059] Similarly, in other rock mechanics tests, the scratch depth is also set according to this requirement, which needs to be less than the minimum peak indentation depth of the specimens at each sampling point to avoid rock breaking.

[0060] See Figure 2 , determine a point for the rock samples from the same construction test site, construct a scatter plot with the abscissa being the scratch axial load and the ordinate being the peak rock breaking load. The scatter points in the scatter plot represent the characteristic points of the rock mass specimens at different construction sites, and the scratch axial load obtained through the rock scratch test is the average load during the scratching process.

[0061] SS4. Fit the relationship curve and equation of scratch axial load - peak rock breaking load, and compare the determination coefficients R of each fitting result 2 to obtain the best fitting model, and the scratch depth corresponding to this model is the best test scratch depth;

[0062] The relationship curve, equation, and determination coefficient R of scratch axial load - peak rock breaking load 2 can be obtained by fitting with common drawing software such as Origin and MATLAB. The closer the determination coefficient is to 1, the better the fitting result. Just take the model with the largest determination coefficient as the best model.

[0063] S3. Partition the best - fit model according to the rock mass cuttability zones determined in step S1 to determine the threshold values for the scratch axial load zones.

[0064] See Figure 2 , since the rock mass samples at different construction sites have been partitioned in step S1, that is, the zone of each point in the scatter plot is known. Therefore, according to the characteristics of the rock mass cuttability zones, select the means a and b of the rock - breaking peak loads of two adjacent sample points in two adjacent zones on the best - fit model as the critical thresholds, and obtain the scratch axial load zone threshold values α and β corresponding to the fitting curve.

[0065] Of course, it is also possible to select the means of the scratch axial loads of two adjacent sample points in two adjacent zones on the best - fit model as the scratch axial load zone threshold values α and β.

[0066] The theoretical errors of the above two methods for determining the scratch axial load zone threshold values are not obvious. In the actual determination process, the method of determining the scratch axial load based on rock mass mechanical parameters can be preferentially selected. This is because the rock mass mechanical test for obtaining rock mass mechanical parameters is a destructive test, and the obtained rock mass mechanical parameters can better characterize the fragmentation characteristics of the rock. The rock scratch test is a non - destructive test. For the mechanical rock - breaking characteristics at the engineering site, it is more reasonable to determine the scratch axial load zone threshold values based on rock mass mechanical parameters.

[0067] S4. Drill holes in the rock mass 1 of the tunnel face, from shallow to deep, and carry out the scratch penetration test on the hole - wall rock mass at the best test scratch depth to obtain the data of the scratch axial load varying with the hole depth.

[0068] See Figure 3 , drill a hole in the rock mass 1 of the construction tunnel face, assemble the hole - wall scratch penetration device 4 onto the drill rod 3 of the drill jumbo 2. The drill jumbo includes components such as a propulsion beam 201, a rock drill 202, a front seat 203, a telescopic oil cylinder 204, a drill rod 3, and a jumbo body. Since the drill jumbo belongs to the prior art, its structure and working principle are not described in detail in this embodiment. See Figure 4, the hole wall scratch penetration device 4 is composed of an adapter 401, a transmission rod 402, transmission teeth 403, a conical head 404, an annular sleeve 405, a gear 406, a motor 407, a servo cylinder 408, and a pick 409. Among them, the adapter 401 can connect the drill rod 3 and the transmission rod 402 together through the grooves at both ends. The bottom of the transmission rod 402 is provided with transmission teeth 403 extending along the length direction of the transmission rod 402. A conical head 404 is installed at the other end of the transmission rod 402. The annular sleeve 405 is sleeved on the transmission rod 402 and can move freely. A gear 406 is installed on the bottom surface of the annular sleeve 405. The gear 406 meshes with the transmission teeth 403. The motor 407 arranged on the outside provides power for the transmission of the gear 406. A servo cylinder 408 is installed below the gear 406. The end face of the telescopic lead screw of the servo cylinder 408 is connected to the pick 409. When the hole wall scratch penetration test is carried out, the hole wall scratch penetration device 4 is sent into the drill hole through the drill rod 3 of the drilling jumbo 2, so that the conical head 404 abuts against the rock mass at the bottom of the hole to keep the device stable. Then, control the servo cylinder 408 to apply a cutting load to the hole wall, adjust and fix the penetration depth of the pick 409 to the optimal test scratch depth, and then start the motor 407 to carry out the hole wall scratch penetration test from shallow to deep. During the test, the servo cylinder 408 transmits the data of the scratch axial load recorded with the change of hole depth to the big data analysis and processing platform 6 through the axial load sensor.

[0069] S5. Through the arrangement of the drill hole array and the collection of scratch test data, use the scratch axial load partition thresholds α and β to construct a characterization cloud map of the cuttability of the rock mass in front of the heading face, so as to accurately guide the modification of the difficult cutting area of the rock mass 1 in front, improve the cuttability of the rock mass and the non-explosive mechanized rock breaking efficiency. At the same time, the rock mass mechanical parameters and their changes in front of the heading face can also be back-calculated using the best fitting model.

[0070] See Figure 5 , carry out the characterization of the cuttability of the rock mass through the scratch axial load partition thresholds α and β: easy mining area (scratch axial load < α); difficult mining area (α < scratch axial load < β); extremely difficult mining area (scratch axial load > β). And as the hole depth changes, the scratch axial load will change, and the cuttability of the rock mass will also change accordingly. According to the interval where the scratch axial load value falls, the cuttability partition of the rock mass can be quickly judged. In addition, the curve of the scratch axial load changing with the hole depth obtained through monitoring can also reflect the distribution characteristics of the rock mass fractures. The location of the cliff-like mutation of the scratch axial load is the development position of the rock mass fractures.

[0071] See Figure 6, according to the evaluation of the zoning characterization of the rock mass in front of the heading face, targeted rock mass modification measures are taken for different difficult-to-mine areas. For example, for the difficult-to-mine area 8, a relief groove is constructed in the difficult-to-mine area 8 to increase the free surface of the rock mass and improve the cutability of the rock mass in the difficult-to-mine area 8; for the extremely difficult-to-mine area 7, hydraulic fracturing boreholes 7 can be constructed first, and then hydraulic fracturing is carried out through the fracturing equipment to promote the generation of new cracks and the expansion of primary fractures in the rock mass 1, thereby reducing the integrity of the rock mass 1 and deteriorating the physical and mechanical properties of the rock mass to achieve the purpose of improving the cutability of the rock mass.

[0072] See Figure 2 , according to the collected scratch test data, through the best-fit model, the peak rock-breaking load, a rock mass mechanical parameter, can be inversely calculated based on the scratch axial load. Similarly, if the relationship between other rock mass mechanical parameters and the scratch axial load is constructed, the corresponding rock mass mechanical parameters can also be deduced from the scratch axial load.

[0073] In order to apply this method more conveniently in actual construction, a method of mutual assistance between mechanical rock breaking and in-situ monitoring can be adopted for construction, that is, during the process of mechanical rock breaking, by monitoring the rock-breaking load (force) on the mechanical cutter, a rough positioning of the difficult / extremely difficult-to-mine area is formed, and then in-situ evaluation is further carried out for this area, saving the cost consumption caused by all-round in-situ monitoring of the entire rock mass area and facilitating rapid construction.

[0074] See Figure 6 , during the on-site mechanical rock-breaking construction, the change of the rock-breaking load on the rock-breaking cutter and the operation condition of the roadheader 5 can be monitored in real time, and the operation state of the roadheader 5 can be optimized and adjusted in time by using the big data analysis and processing platform 6 to dynamically identify and warn the difficult-to-cut area, and then optimize the hole array arrangement and the in-situ evaluation process of the rock mass cutability to achieve continuous and intelligent safe and efficient rock breaking.

[0075] The roadheader 5 is composed of a cutting part 501, a fuselage body 502, a traveling part 503, a scraper plate part 504, a rear support part 505, a first conveyor 506, etc. Since the roadheader belongs to the prior art, the structure and working principle thereof are not described in detail in this embodiment.

[0076] Specifically: When the cantilever roadheader 5 is tunneling, the change (data) of the rock-breaking load of the picks on the tunneling head of the roadheader is monitored by sensors to dynamically identify the lithology of the cut rock (soft rock / hard rock, hardness degree). At the same time, the cutability of the rock mass ahead is comprehensively judged by monitoring the working state of the roadheader (changes in input power, body vibration, etc.), so as to realize the dynamic identification of difficult cutting areas, and then adjust the key cutting areas and working parameters (power, speed, torque, etc.) of the roadheader. For example, when the rock-breaking load transmitted back shows an abnormality (significantly too large) during the rock-breaking process of the cutting head and the operating data shows significant fluctuations, the area being cut can be regarded as a difficult / extremely difficult mining area. Then, the control terminal can be used to adjust the machine to bypass this area and cut the next rock mass. For this area, the above evaluation method can be used to specifically identify the cutting difficulty and take modification measures. Through this dynamic monitoring of the roadheader, the general range of difficult mining areas can be initially identified. For these difficult mining ranges, by using the method provided by the present invention to evaluate the cutability of the rock mass, the purposes of greatly shortening the evaluation workload and saving costs can be achieved.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Any equivalent transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. An in-situ evaluation method for rock mass mechanical parameters and engineering characteristics, characterized in that It includes the following steps: S1. Through on-site mechanical rock breaking tests, collect the characterization parameters of rock breaking effects under different lithological environmental conditions, and conduct rock mass cuttability zoning for the rock masses at different construction test sites; S2. Take samples from the construction test sites, obtain the rock mass mechanical parameters of the rock masses under different lithological environments through indoor rock mass mechanical tests, conduct indoor rock scratch tests on the sampled rock masses, fit the scratch axial load - rock mass mechanical parameter curves at different scratch depths, obtain the best fitting model, and determine the optimal test scratch depth; S3. According to the rock mass cuttability zoning determined in step S1, partition the best fitting model to determine the scratch axial load zoning threshold; S4. Drill holes in the rock mass of the tunnel face, from shallow to deep, and conduct hole wall rock scratch penetration tests at the optimal test scratch depth to obtain the data of the scratch axial load varying with the hole depth; S5. Through the layout of the drill hole array and the collection of scratch test data, use the scratch axial load zoning threshold to construct a cuttability characterization cloud map of the rock mass in front of the tunnel face, so as to accurately guide the modification of difficult-to-cut areas of the rock mass in front, improve the cuttability of the rock mass and the non-explosive mechanized rock breaking efficiency. At the same time, the rock mass mechanical parameters and their changes in front of the tunnel face can also be back-calculated using the best fitting model.

2. The in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 1, characterized in that The construction method of the rock mass cuttability zoning is as follows: Carry out a series of on-site mechanical rock breaking tests under different lithological environmental conditions and the same operating state of the rock breaking machinery. Take the rock breaking efficiency and the cutter head loss as the rock breaking effect characterization parameters. Among them, determine one point for the rock mass at the same construction site, construct a scatter plot of cutter head loss - rock breaking efficiency, and take the average rock breaking efficiency and the average cutter head loss in the scatter plot as the characterization thresholds to conduct rock mass cuttability zoning: the easy mining area is where the rock breaking efficiency is higher than the average value and the cutter head loss is lower than the average value; the difficult mining area is where the rock breaking efficiency is lower than the average value and the cutter head loss is lower than the average value, or the rock breaking efficiency is higher than the average value and the cutter head loss is higher than the average value; the extremely difficult mining area is where the rock breaking efficiency is lower than the average value and the cutter head loss is higher than the average value.

3. The in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 1, characterized in that The method for obtaining the best fitting model through indoor rock scratch tests is as follows: SS1. Drill rock cores at the rock breaking test sites under different lithological environments, and process the rock cores into standard specimens; SS2. Conduct indoor rock mass mechanical tests to obtain the rock mass mechanical parameters of the specimens at each sampling point at different construction test sites; SS3. Set a series of scratch depths, and conduct indoor rock scratch tests on the specimens at each sampling point at different construction test sites: keep the scratch depth unchanged, obtain the scratch axial loads of different specimens, and make scatter plots of scratch axial load - rock mass mechanical parameters at a series of scratch depths; SS4. Fit the relationship curve and equation of scratch axial load - rock mass mechanical parameters, and compare the determination coefficients of each fitting result to obtain the best fitting model. The scratch depth corresponding to this model is the optimal test scratch depth.

4. The in-situ evaluation method of rock mass mechanical parameters and engineering characteristics according to claim 3, characterized in that, The rock cores are drilled from the same piece of mother rock on the tunnel face of the corresponding construction site to ensure that the processed standard specimens have almost the same physical and mechanical properties.

5. The in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 3, characterized in that The rock mass mechanical parameters select the peak rock breaking load, uniaxial / triaxial compressive strength of the rock, tensile strength, and elastic modulus.

6. The in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 3, characterized in that The setting of the scratch depth needs to be less than the minimum peak indentation depth in the specimens at each sampling point. With a progressive unit of 0.05 mm, the maximum value of the minimum peak indentation depth is used to set a series of scratch depth gradients.

7. The in-situ evaluation method of rock mass mechanical parameters and engineering characteristics according to claim 3, characterized in that, There are two methods for determining the threshold of the axial load partition of the scratch: (1) According to the characteristics of the rock mass cutability partition, select the mean value of the rock mass mechanical parameters of two adjacent specimen points in two adjacent partitions on the best fitting model as the critical threshold, and obtain the threshold of the axial load partition of the scratch corresponding to the fitting curve; (2) According to the characteristics of the rock mass cutability partition, select the mean value of the axial load of the scratch of two adjacent specimen points in two adjacent partitions on the best fitting model as the threshold of the axial load partition of the scratch.

8. The in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 1, characterized in that, The operating steps of the scratch penetration test on the rock mass of the hole wall are as follows: Drill a hole on the construction face, assemble the hole wall scratch penetration device onto the drill rod of the drilling jumbo, adjust and fix the scratch depth to the optimal test scratch depth, and conduct the scratch penetration test on the hole wall from shallow to deep in the hole. Record and transmit the data of the axial load of the scratch varying with the hole depth through the axial load sensor to the big data analysis and processing platform.

9. A in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 8, characterized in that The hole wall scratch penetration device consists of an adapter, a transmission rod, transmission teeth, a conical head, an annular sleeve, a gear, a motor, a servo electric cylinder, and a pick. Among them, the adapter can connect the drill rod and the transmission rod through the grooves at both ends. The bottom of the transmission rod is provided with transmission teeth extending along the length direction of the transmission rod. A conical head is installed at the other end of the transmission rod. The annular sleeve is sleeved on the transmission rod and can move freely. A gear is installed on the bottom surface of the annular sleeve, and the gear meshes with the transmission teeth. The motor arranged on the outside provides power for the transmission of the gear. A servo electric cylinder is installed below the gear, and the end face of the telescopic lead screw of the servo electric cylinder is connected to the pick.

10. A in-situ evaluation method for rock mass mechanical parameters and engineering characteristics according to claim 1, characterized in that, According to the evaluation of the characterization of the rock mass cutability partition in front of the heading face, targeted rock mass modification measures are taken for different difficult-to-mine areas, including: for difficult-to-mine areas, increase the free surface of the rock mass by constructing relief grooves in the difficult-to-mine areas to improve the cutability of the rock mass in the difficult-to-mine areas; for extremely difficult-to-mine areas, first construct hydraulic fracturing boreholes, and then conduct hydraulic fracturing through fracturing equipment to promote the generation of new cracks and the expansion of primary fractures in the rock mass, thereby reducing the integrity of the rock mass and deteriorating the physical and mechanical properties of the rock mass to achieve the purpose of improving the cutability of the rock mass.

Images