Ground fracturing control method and system based on hard roof rock impact energy

Abstract

The present invention discloses a ground fracturing control method and system based on the rock pressure energy of a hard roof, which relates to the field of coal mining technology, including: calculating the elastic modulus and shear modulus data of the hard roof; measuring the thickness and stiffness of each layer of the underlying rock layer within the range of n times the thickness of the hard roof below the hard roof, and determining the overall stiffness data of the underlying rock layer; determining the height of the overburden layer acting on the hard roof, and calculating the load data above the hard roof according to the height of the overburden layer; constructing an energy calculation model according to the modulus data, stiffness data and load data, calculating the energy of the periodic fracture of the hard roof through the model and performing ground fracturing control. The present invention is based on a ground fracturing control method and system based on the rock pressure energy of a hard roof, analyzing the relationship between the roof thickness, fracture size, load bearing and energy concentration and dispersion when the thick hard roof is periodically fractured, realizing precise control of ground fracturing, and improving the safety of coal mining.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, and more particularly to a ground fracturing control method and system based on the impact ground pressure energy of a hard roof. Background Art

[0002] Hard roof refers to those rock layers with high strength and complete structure in the mining area, mainly including sandstone layers, siltstone, etc. During the mining process, due to its unique physical properties, the hard roof often has a large area of ​​hanging roof phenomenon and cannot collapse in time. When the hanging roof space accumulates to the critical value of breaking, the hard roof will suddenly collapse, causing serious pressure shock to the working face and tunnel. Therefore, how to effectively deal with the strong mine pressure caused by the hard roof has always been one of the key challenges that need to be solved in coal mine production.

[0003] In order to solve the problem of hard roof, two main methods are currently adopted: strengthening support and cutting the roof to relieve pressure. In terms of strengthening support, hydraulic supports with high support resistance are usually selected on the working face, while high-strength anchor rods and cables are used for support in the tunnel. Although this method can effectively improve the ability of the mining area to withstand strong mine pressure, it is essentially a means of passively increasing the bearing capacity. Therefore, although it has a certain effect, it is accompanied by high one-time investment costs and potential safety hazards. In contrast, cutting the roof to relieve pressure is an active governance method, which is usually implemented through hydraulic fracturing. Hydraulic fracturing controls the intensity of rock burst pressure by destroying the integrity of the hard roof, reducing the pressure step of the roof, and reducing the energy release gradient of the mining area. When using hydraulic fracturing technology to control the hard roof, since the relationship between the roof thickness, fracture size, load and energy concentration during the periodic fracture of the hard roof has not been deeply analyzed, it is difficult to accurately control the energy release of the hard roof during rock burst through ground fracturing technology. Under such circumstances, the hard roof will quickly accumulate and release a large amount of elastic energy during periodic breaking, which can easily induce high-energy mine earthquakes, and then cause dynamic disasters on the working face, posing a serious threat to the safety of coal mine workers.

[0004] Therefore, how to propose a ground fracturing control method and system based on the impact ground pressure energy of the hard roof, analyze the relationship between the roof thickness, fracture size, load and energy concentration and dispersion during the periodic fracture of the thick and hard roof, realize the precise control of ground fracturing, and improve the safety of coal mining, is a problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of this, the present invention provides a ground fracturing control method and system based on the rock pressure energy of the hard roof, analyzes the relationship between the roof thickness, fracture size, load and energy concentration and dispersion during the periodic fracture of the thick hard roof, realizes the precise control of ground fracturing, and improves the safety of coal mining. In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The ground fracturing control method based on the rock burst energy of the hard roof includes:

[0007] In a hard roof with a thickness of h, a rock sample of the hard roof is taken for a triaxial compression test to measure its mechanical parameters, elastic modulus E and shear modulus G;

[0008] Measure the thickness of each overburden layer within the range of n times the thickness of the hard roof below the hard roof, and record the thickness values ​​as h1, h2, h3, ..., h i , and the corresponding stiffness of each layer of overburden, the stiffness values ​​are recorded as k1, k2, k3, ..., k i ; The underlying rock layer within the range of n times the thickness of the hard roof below the hard roof is regarded as a whole, and its overall stiffness k0 is determined, where

[0009]

[0010] Determine the height H of the overburden layer acting on the hard roof, and the calculation formula is: in According to the height H of the overburden, the load q above the hard roof is determined, q = γ × H, where γ represents the density of the overburden;

[0011] An energy calculation model is constructed based on modulus data, stiffness data and load data, and the energy U of the periodic fracture of the hard top plate is calculated through the model;

[0012]

[0013] Among them, C = κGA, D = EI, I is the inertia matrix of the hard roof section with respect to the y-axis; A is the cross-sectional area of ​​the hard roof, κ is the shear correction coefficient of the hard roof section, and L1 is the periodic breaking step of the hard roof;

[0014] Surface fracturing is regulated based on the energy of periodic fracture of the hard roof.

[0015] Optionally, the surface fracturing regulation based on the energy of periodic breaking of the hard roof includes: setting the fracturing flow rate, fracturing step distance and number of fracturing times based on the energy U of periodic breaking of the hard roof.

[0016] Optionally, a ground fracturing control system based on rock impact energy of a hard roof includes: an experimental module: used for taking a rock layer sample of a hard roof with a thickness of h to perform a triaxial compression test to measure its mechanical parameters elastic modulus E and shear modulus G;

[0017] Measurement module: used to measure the thickness of each overburden layer within the range of n times the thickness of the hard roof below the hard roof. The thickness values ​​are recorded as h1, h2, h3, ..., h i , and the corresponding stiffness of each layer of overburden, the stiffness values ​​are recorded as k1, k2, k3, ..., k i ; The underlying rock layer within the range of n times the thickness of the hard roof below the hard roof is regarded as a whole, and its overall stiffness k0 is determined, where

[0018] Calculation module: used to determine the height H of the overburden layer acting on the hard roof. The calculation formula is: in According to the height H of the overburden, the load q above the hard roof is determined, q = γ × H, where γ represents the density of the overburden;

[0019] Model building module: used to build an energy calculation model based on modulus data, stiffness data and load data, and calculate the energy U of the periodic fracture of the hard top plate through the model;

[0020]

[0021] Among them, C = κGA, D = EI, I is the inertia matrix of the hard roof section with respect to the y-axis; A is the cross-sectional area of ​​the hard roof, κ is the shear correction coefficient of the hard roof section, and L1 is the periodic breaking step of the hard roof;

[0022] Control module: used to control ground fracturing according to the energy of periodic breaking of hard roof.

[0023] Optionally, the control module further includes: setting the fracturing flow rate, fracturing step distance and fracturing times according to the energy U of the periodic breaking of the hard roof.

[0024] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a ground fracturing control method and system based on the rock impact energy of a hard roof, which has the following beneficial effects:

[0025] The present invention proposes a ground fracturing control method based on the rock pressure energy of a hard roof, comprising: calculating the elastic modulus and shear modulus data of the hard roof; measuring the thickness and stiffness of each layer of the underlying rock layer within a range of n times the thickness of the hard roof below the hard roof, and determining the overall stiffness data of the underlying rock layer; determining the height of the overlying rock layer acting on the hard roof, and calculating the load data above the hard roof according to the height of the overlying rock layer; constructing an energy calculation model according to the modulus data, stiffness data and load data, and calculating the energy of the periodic fracture of the hard roof through the model; and performing ground fracturing control according to the energy of the periodic fracture of the hard roof. The present invention is based on the ground fracturing control method and system of the energy of hard roof impact ground pressure, analyzes the relationship between the roof thickness, fracture size, load and energy concentration and dispersion during the periodic fracture of the hard roof, realizes the precise control of ground fracturing, improves the safety of coal mining, and precisely controls the ground fracturing according to the energy of the hard roof impact ground pressure, regards the underlying rock layer of the hard roof as a whole, and accurately measures its overall stiffness; secondly, uses a specific energy formula to accurately calculate the energy value required for ground fracturing; finally, based on the obtained energy level, scientifically controls the fracturing flow rate, fracturing step distance and fracturing times to achieve optimization of energy control. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 A schematic flow chart of a ground fracturing control method based on hard roof rock impact energy provided by the present invention.

[0028] Figure 2 A structural framework diagram of a ground fracturing control system based on hard top plate rock impact energy provided by the present invention.

[0029] Figure 3 This is a mechanical model diagram of the hard top plate provided by the present invention.

[0030] Among them, 1-hard roof, 2-overlying rock strata, 3-underlying rock strata. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The present invention proposes a ground fracturing control method and system based on the energy of the rock pressure impact of the hard roof. The ground fracturing is accurately controlled according to the energy of the rock pressure impact of the hard roof, and the overlying rock layer under the hard roof is regarded as a whole, and its overall stiffness is accurately measured; secondly, a specific energy formula is used to accurately calculate the energy value required for ground fracturing; finally, based on the obtained energy level, the fracturing flow rate, fracturing step distance and fracturing times are scientifically controlled to achieve optimization of energy control.

[0033] The embodiment of the present invention discloses a ground fracturing control method based on the rock impact energy of a hard roof, such as Figure 1 As shown, it includes: calculating the elastic modulus and shear modulus data of the hard roof; measuring the thickness and stiffness of each layer of the underlying rock layer within the range of n times the thickness of the hard roof below the hard roof, and determining the overall stiffness data of the underlying rock layer; determining the height of the overburden layer acting on the hard roof, and calculating the load data above the hard roof according to the height of the overburden layer; constructing an energy calculation model according to the modulus data, stiffness data and load data, and calculating the energy of the periodic fracture of the hard roof through the model; and performing ground fracturing regulation according to the energy of the periodic fracture of the hard roof.

[0034] In a specific embodiment, a ground fracturing control method based on the rock impact energy of a hard roof is as follows: Figure 3 As shown, specifically including:

[0035] Step 1: In a hard top plate with a thickness of h, a representative rock sample of the rock layer is taken to perform a triaxial compression test to measure its mechanical parameters, the elastic modulus E and the shear modulus G.

[0036] Step 2: Measure the thickness of each overburden layer within the range of five times the thickness of the hard roof below the hard roof, and record the thickness values ​​as h1, h2, h3, ..., h i , and the corresponding stiffness of each layer of overburden, the stiffness values ​​are recorded as k1, k2, k3, ..., k i .

[0037] Step 3: Consider the overburden within five times the thickness of the hard roof as a whole and determine its overall stiffness k0, where:

[0038] Step 4: Determine the height H of the overburden layer acting on the hard roof. The calculation formula is: in

[0039] Step 5: Determine the load q above the hard top plate according to the height H of the overlying rock formation, that is, q = γ × H, where γ represents the density of the rock formation.

[0040] Step 6: Calculate the energy U of the periodic fracture of the hard top plate.

[0041]

[0042] Among them, C = κGA, D = EI, I is the inertia matrix of the hard top plate section with respect to the y-axis; A is the cross-sectional area of ​​the hard top plate, κ is the shear correction coefficient of the hard top plate section, which is related to the cross-sectional shape and is taken as 5 / 6 here; L1 is the periodic breaking step of the hard top plate.

[0043] Step 7: Based on the calculated hard roof periodic fracture energy U, the fracturing flow rate, fracturing step distance and fracturing times will be accurately set. 6 At level J, the fracturing flow rate should be set to 500m 3 / min, the fracturing step is set to 50m, and three fracturing operations are required; if the fracturing energy is 10 5 For level J, the fracturing flow rate is adjusted to 400m 3 / min, the fracturing step distance was increased to 80m, and two fracturings were performed; and when the fracturing energy was reduced to 10 4 At level J, no fracturing operation is required.

[0044] In a specific embodiment, a ground fracturing control method based on the rock impact energy of a hard roof comprises the following specific steps:

[0045] Step 1, taking a certain working face of a coal mine as an example, in a hard roof 1 with a thickness of 14.5m, a representative rock layer sample of the rock layer is taken for a triaxial compression test, and its mechanical parameters are measured, the elastic modulus E is 4.0GPa and the shear modulus G is 1.25GPa.

[0046] Step 2: Measure the thickness of each layer of overburden within a thickness range of 72.5m below the hard roof, a total of six layers, with thickness values ​​of 6.2m, 20.9m, 15.5m, 18.3m, 8.2m, 3.4m and the corresponding stiffness of each layer of overburden, with stiffness values ​​of 1025MN / m, 1096MN / m, 996MN / m, 1030MN / m, 912MN / m, 1120MN / m respectively.

[0047] Step 3: Consider the overburden within the 72.5m thickness range below the hard roof as a whole, and determine its overall stiffness k0, and calculate

[0048]

[0049] Step 4: Determine the height H of the overburden stratum 2 acting on the hard roof. The calculation formula is The calculated H = 479m, where

[0050]

[0051] Step 5: According to the height H of the overlying rock layer 2, determine the load q above the hard roof, that is, q = γ × H. Among them, γ represents the density of the rock layer, and the average bulk density of the direct top coal rock layer γ ZJD =2609kg / m 3 ; Calculated q = 1.25MPa.

[0052] Step 6: Calculate the ground fracturing energy U of the hard roof impact ground pressure.

[0053]

[0054] Among them, C = κGA, D = EI, I is the inertia matrix of the hard top plate section with respect to the y-axis; A is the cross-sectional area of ​​the hard top plate, κ is the shear correction coefficient of the hard top plate section, which is related to the cross-sectional shape and is taken as 5 / 6 here; L1 is the periodic breaking step of the hard top plate.

[0055] It can be calculated that when the cantilever length L1 = 5m, U = 3.4 × 10 3 J; When the cantilever length L1 = 10m, U = 3.29 × 10 4 J; When the cantilever length L1 = 15m, U = 1.45 × 10 5 J; When the cantilever length L1 = 20m, U = 4.45 × 10 5 J; When the cantilever length L1 = 25m, U = 1.10 × 10 6 J.

[0056] Step 7: According to the calculated energy U of the hard roof periodic fracture, set the fracturing flow rate, fracturing step and number of fracturing times. The greater the energy U of the hard roof periodic fracture, the greater the impact on the working face and the tunnel. The greater the periodic fracture energy U, the more sufficient the ground fracturing is required to fracture the hard roof, which requires a larger fracturing flow rate and number of fracturing times, and a smaller fracturing step. Therefore, the settings are as follows: When the cantilever length is 25m, the fracturing energy reaches 10 6 For Class J, the fracturing flow rate should be set to 500m 3 / min, the fracturing step is set to 50m, and three fracturing operations are required; when the cantilever length is 15m and 20m, the fracturing energy is 10 5For level J, the fracturing flow rate is adjusted to 400m 3 / min, the fracturing step length was increased to 80m, and two fracturings were performed; when the cantilever length was 5m and 10m, the fracturing energy was reduced to 10 4 For Grade J, no fracturing operation is required.

[0057] In a specific embodiment, a ground fracturing control system based on hard roof impact ground pressure energy, such as Figure 2 As shown, including:

[0058] Experimental module: used to calculate elastic modulus and shear modulus data of hard top plate;

[0059] Measurement module: used to measure the thickness and stiffness of each layer of the underlying rock layer within the range of n times the thickness of the hard roof below the hard roof, and determine the overall stiffness data of the underlying rock layer;

[0060] Calculation module: used to determine the height of the overlying rock layer acting on the hard roof, and calculate the load data above the hard roof based on the height of the overlying rock layer;

[0061] Model building module: used to build an energy calculation model based on modulus data, stiffness data and load data, and calculate the energy of periodic fracture of the hard top plate through the model;

[0062] Control module: used to control ground fracturing according to the energy of periodic breaking of hard roof.

[0063] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0064] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A ground fracturing control method based on hard roof rock impact energy, characterized in that: include: In a hard roof with a thickness of h, a rock sample of the hard roof is taken for a triaxial compression test to measure its mechanical parameters, elastic modulus E and shear modulus G; Measure the thickness of each overburden layer within the range of n times the thickness of the hard roof below the hard roof, and record the thickness values ​​as h1, h2, h3, ..., h i , and the corresponding stiffness of each layer of overburden, the stiffness values ​​are recorded as k1, k2, k3, ..., k i ; The underlying rock layer within the range of n times the thickness of the hard roof below the hard roof is regarded as a whole, and its overall stiffness k0 is determined, where Determine the height H of the overburden layer acting on the hard roof, and the calculation formula is: in According to the height H of the overburden, the load q above the hard roof is determined, q = γ × H, where γ represents the density of the overburden; An energy calculation model is constructed based on modulus data, stiffness data and load data, and the energy U of the periodic fracture of the hard top plate is calculated through the model; Among them, C = κGA, D = EI, I is the inertia matrix of the hard roof section with respect to the y-axis; A is the cross-sectional area of ​​the hard roof, κ is the shear correction coefficient of the hard roof section, and L1 is the periodic breaking step of the hard roof; Surface fracturing is regulated based on the energy of periodic fracture of the hard roof.

2. The ground fracturing control method based on hard roof rock impact energy according to claim 1, characterized in that: The surface fracturing regulation based on the energy of periodic breaking of the hard roof includes: setting the fracturing flow rate, fracturing step distance and fracturing times based on the energy U of periodic breaking of the hard roof.

3. A ground fracturing control system based on hard roof rock impact energy, characterized in that: include: Experimental module: used to take rock samples from a hard roof with a thickness of h to conduct triaxial compression experiments and measure its mechanical parameters elastic modulus E and shear modulus G; Measurement module: used to measure the thickness of each overburden layer within the range of n times the thickness of the hard roof below the hard roof. The thickness values ​​are recorded as h1, h2, h3, ..., h i , and the corresponding stiffness of each layer of overburden, the stiffness values ​​are recorded as k1, k2, k3, ..., k i ; The underlying rock layer within the range of n times the thickness of the hard roof below the hard roof is regarded as a whole, and its overall stiffness k0 is determined, where Calculation module: used to determine the height H of the overburden layer acting on the hard roof. The calculation formula is: in According to the height H of the overburden, the load q above the hard roof is determined, q = γ × H, where γ represents the density of the overburden; Model building module: used to build an energy calculation model based on modulus data, stiffness data and load data, and calculate the energy U of the periodic fracture of the hard top plate through the model; Among them, C = κGA, D = EI, I is the inertia matrix of the hard roof section with respect to the y-axis; A is the cross-sectional area of ​​the hard roof, κ is the shear correction coefficient of the hard roof section, and L1 is the periodic breaking step of the hard roof; Control module: used to control ground fracturing according to the energy of periodic breaking of hard roof.

4. The ground fracturing control system based on hard roof rock impact energy according to claim 3 is characterized in that: The control module also includes: setting the fracturing flow rate, fracturing step distance and fracturing times according to the energy U of the periodic breaking of the hard roof.

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