Design method of support parameters for expansive rock tunnels in metal mines considering service life

Abstract

The present invention discloses a method for designing support parameters for expansive rock tunnels in metal mines that takes service time into consideration. The method determines rock strain and rock stress by establishing a relative humidity distribution equation and a relative temperature distribution equation inside the rock; determines the tensile damage threshold and the shear damage threshold based on the uniaxial tensile strength, compressive strength, and rock stress; obtains volume force and total support strength, and determines a first relationship curve in combination with rock strain and rock stress. The standard value of the tunnel's ultimate convergence deformation is determined based on the tunnel's limit width for functional failure, the non-pedestrian side width, the mine car width, and the pedestrian side width. In combination with the first relationship curve, a functional relationship between the total support strength and the tunnel's maximum safe service life is established, and the support parameters are determined. This application takes into account the timeliness of the continuous accumulation of strain in the rock during its service period, establishes a functional relationship between the total support strength and the service life, and improves the safety, rationality, and economy of the support design.

Description

Technical Field

[0001] The present invention relates to the technical field of metal mine support, and in particular to a method for designing support parameters of metal mine expansion rock tunnels taking service time into consideration. Background Art

[0002] When tunneling in deep or humid environments, metal mines often penetrate highly expansive rock formations. Due to their unique hygroscopic and expansive properties, these rocks expand in volume during long-term contact with groundwater or moist air, causing continuous deformation and contraction of the tunnel cross-section. As tunnels age, the expansive effects gradually accumulate. Failure to implement appropriate support measures can easily lead to tunnel instability, block fall, vault subsidence, and even collapse.

[0003] Furthermore, as mining depth increases, the ambient temperature of the tunnels also rises significantly. Numerous studies have shown that high temperatures not only affect the mechanical properties of rock but also exacerbate moisture migration and hygroscopic expansion, creating a "temperature-humidity compound excitation" effect. Traditional models often fail to fully account for the combined effects of temperature on moisture migration and rock expansion-damage behavior, resulting in large prediction errors and poor applicability.

[0004] In support design, the current industry generally determines anchor bolt or shotcrete parameters based on the initial excavation stress state. This ignores the time-sensitive nature of strain accumulation in expansive rock during its service life, and fails to establish a functional relationship between support strength and service life. This lack of a design concept guided by "service life" often leads to a dilemma in support design: either excessive redundancy or insufficient safety margins. To improve the safety, rationality, and cost-effectiveness of support design, a scientific, systematic, and practical support design method is urgently needed. Summary of the Invention

[0005] Based on this, it is necessary to propose a method for designing support parameters of expansive rock tunnels in metal mines considering service time in response to the above problems.

[0006] A method for designing support parameters for expansive rock tunnels in metal mines taking service time into consideration, the method comprising:

[0007] Establish the relative humidity distribution equation and relative temperature distribution equation inside the rock;

[0008] determining rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation;

[0009] Obtaining uniaxial tensile strength and compressive strength, and determining a tensile damage threshold and a shear damage threshold based on the uniaxial tensile strength, compressive strength, and the rock stress;

[0010] determining a damage variable according to the tensile damage threshold and the shear damage threshold, and updating the rock strain according to the damage variable until a time limit expires;

[0011] Obtaining body force and total support strength, and determining a first relationship curve in combination with the rock strain and rock stress, wherein the first relationship curve is a relationship curve between rock horizontal displacement convergence deformation and the total support strength;

[0012] Obtaining a maximum width of a tunnel at which a function fails, a width on a non-pedestrian side, a width of a mine car, and a width on a pedestrian side, and determining a standard value of a maximum convergence deformation of the tunnel based on the maximum width of a tunnel at which a function fails, the width on a non-pedestrian side, the width of a mine car, and the width on a pedestrian side;

[0013] Establishing a functional relationship between the total support strength and the maximum safe service life of the roadway based on the first relationship curve and the roadway limit convergence deformation standard value; determining the total support strength when the maximum safe service life of the roadway is known;

[0014] The support parameters are determined according to the total support strength, and the support parameters include: anchor bolt spacing, anchor bolt row spacing and shotcrete thickness.

[0015] In one embodiment, determining rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation includes:

[0016] determining the relative humidity of the rock according to the relative humidity distribution equation;

[0017] Determining the relative temperature of the rock according to the relative temperature distribution equation;

[0018] determining rock strain according to the relative humidity increments corresponding to the relative humidity of the rock at different times, the relative temperature increments corresponding to the relative temperature of the rock at different times, and the rock mechanical state;

[0019] determining rock stress based on the rock strain;

[0020] Determining the tensile damage threshold and the shear damage threshold according to the uniaxial tensile strength, the compressive strength and the rock stress includes:

[0021] determining a tensile damage threshold based on the uniaxial tensile strength and the maximum principal stress component in the rock stress;

[0022] The shear damage threshold is determined according to the compressive strength and the minimum principal stress component, the maximum principal stress component and the internal friction angle in the rock stress.

[0023] In one embodiment, determining the support parameter according to the total support strength includes:

[0024] Determining the anchor support strength according to the total support strength;

[0025] Obtaining the tensile strength and diameter of the anchor rods, and determining the anchor rod spacing and the anchor rod row spacing according to the anchor rod support strength, the tensile strength and the diameter of the anchor rods;

[0026] Obtaining the anchor net support strength, and determining the shotcrete support strength according to the total support strength, the anchor rod support strength, and the anchor net support strength;

[0027] The excavation radius of the circular roadway tunnel and the initial compressive strength of the shotcrete are obtained; and the thickness of the shotcrete is determined according to the excavation radius of the circular roadway tunnel and the initial compressive strength of the shotcrete.

[0028] In one embodiment,

[0029] The relative humidity distribution equation is as follows:

[0030]

[0031]

[0032] Among them, H RH is the relative humidity of the rock; Is the gradient operator, which represents the vector composed of the partial derivatives of the multivariate function in each coordinate direction; K h (T,D) is the humidity diffusion coefficient, which is a function of temperature and damage, is the initial humidity diffusion coefficient. In the initial state, D is 0; is a constant; is the critical damage value, that is, when the damage is equal to or greater than The humidity diffusion coefficient suddenly increases to a constant value when ; t is time; x, y and z are the coordinates of each point in the rock; T is the rock temperature; T0 is the reference temperature; is the temperature sensitivity coefficient; is the partial derivative of rock relative humidity with respect to time;

[0033] The relative temperature distribution equation is as follows:

[0034]

[0035] Among them, T is the relative temperature of rock, c is the specific heat capacity of rock, k is the thermal conductivity of rock, ρ is the density of rock, t is time, is the gradient operator, is the partial derivative of the rock relative temperature with respect to time.

[0036] In one embodiment, the rock strain is determined based on the relative humidity increment corresponding to the relative humidity of the rock at different times, the relative temperature increment corresponding to the relative temperature of the rock at different times, and the rock mechanical state by the following expression:

[0037] (4)

[0038] (5)

[0039] ,

[0040] (7)

[0041] in, is the hygroscopic expansion coefficient, H RH is the relative humidity, L is the rock expansion rate during the water absorption expansion test, is the expansion strain caused by moisture absorption of rock, is the increase in relative humidity, is the Kronecker function, is the thermal expansion strain, is the coefficient of thermal expansion, is the temperature increment, is the initial thermal expansion coefficient, D is the damage variable, is the critical damage value, is a constant value; is the strain caused by mechanical load, For rock strain.

[0042] In one embodiment, determining the rock stress according to the rock strain is achieved by the following expression:

[0043] , i=1,2,3, j=1,2,3

[0044] = , i=j

[0045] in, is the rock stress, which is a tensor; is the rock strain, is the volumetric strain, is the Lame elastic constant; G is the shear modulus, G=E / 2(1+ ), E is the elastic modulus, , and E are the elastic moduli of the undamaged material and the damaged material respectively, D is the damage variable, Refers to Poisson's ratio; is the Kronecker function; is the coefficient of hygroscopic expansion; is the relative humidity increment; H RH is the relative humidity of the rock; is the relative temperature increment, T is the relative temperature of the rock, is the coefficient of thermal expansion.

[0046] In one embodiment, the tensile damage threshold is determined based on the uniaxial tensile strength and the maximum principal stress component in the rock stress; and the shear damage threshold is determined based on the compressive strength and the minimum principal stress component, the maximum principal stress component, and the internal friction angle in the rock stress by the following expressions:

[0047]

[0048]

[0049] in, is the tensile damage threshold; is the shear damage threshold; is the maximum principal stress component of rock stress; is the minimum principal stress component of rock stress; Uniaxial tensile strength; Compressive strength; is the internal friction angle;

[0050] The damage variable is determined according to the magnitude of the tensile damage threshold and the shear damage threshold by the following expression:

[0051]

[0052] Where D is the damage variable; is the maximum tensile strain; is the compressive principal strain; is the maximum principal strain; is the minimum principal strain.

[0053] In one embodiment, the acquisition of the body force and the total support strength and the determination of the first relationship curve in combination with the rock strain and rock stress are achieved by the following expression:

[0054]

[0055] (14)

[0056] , i=1,2,3, j=1,2,3

[0057] = , i=j

[0058] in, is the rock stress, which is a tensor; is the rock strain, is the volumetric strain, is the Lame elastic constant; G is the shear modulus, G=E / 2(1+ ), E is the elastic modulus, , and E are the elastic moduli of the undamaged material and the damaged material respectively, D is the damage variable, Refers to Poisson's ratio; is the Kronecker function; is the coefficient of hygroscopic expansion; is the relative humidity increment; H RH is the relative humidity of the rock; is the relative temperature increment, T is the relative temperature of the rock, is the coefficient of thermal expansion; is the displacement component in the i direction, is the displacement component in the j direction, x i and is the spatial coordinate, is the gradient operator, is the rock stress, f is the body force, is the total support strength.

[0059] In one embodiment, the determination of the tunnel limit convergence deformation standard value based on the tunnel function failure limit width, non-pedestrian side width, mine car width, and pedestrian side width is achieved by the following expression:

[0060]

[0061] in, is the standard value of the tunnel's ultimate convergence deformation; F is the limit width of the tunnel function failure; s is the safety factor; a is the width on the non-pedestrian side; A1 is the width of the mine car; c is the width on the pedestrian side;

[0062] The functional relationship between the total support strength and the maximum safe service life of the tunnel is expressed as follows:

[0063]

[0064] Among them, t d is the maximum safe service life of the tunnel; P is the total support strength, 、 、 is a constant coefficient.

[0065] In one embodiment, the support parameter is determined according to the total support strength by the following expression:

[0066]

[0067]

[0068]

[0069] Among them, P is the total support strength; P b is the anchor support strength; P m is the anchor net support strength; P s is the support strength of shotcrete; is the initial compressive strength of shotcrete; R is the excavation radius of the circular roadway tunnel; is the thickness of shotcrete; d is the diameter of anchor rod; is the tensile strength of the anchor rod; L b,x is the anchor spacing; L b,y Anchor rod spacing.

[0070] The present application establishes a relative humidity distribution equation and a relative temperature distribution equation inside the rock; determines the rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation; obtains the uniaxial tensile strength and compressive strength, and determines the tensile damage threshold and the shear damage threshold according to the uniaxial tensile strength, the compressive strength and the rock stress; determines the damage variable according to the magnitude of the tensile damage threshold and the shear damage threshold, and updates the rock strain according to the damage variable until the time expires; obtains the volume force and the total support strength, and determines the first relationship curve in combination with the rock strain and the rock stress, wherein the first relationship curve is the horizontal displacement of the rock A relationship curve between the convergence deformation and the total support strength; obtaining the maximum width of the tunnel at which the function fails, the width on the non-pedestrian side, the width of the mine car, and the width on the pedestrian side, and determining the standard value of the tunnel's maximum convergence deformation based on the maximum width of the tunnel at which the function fails, the width on the non-pedestrian side, the width of the mine car, and the width on the pedestrian side; establishing a functional relationship between the total support strength and the tunnel's maximum safe service life based on the first relationship curve and the standard value of the tunnel's maximum convergence deformation; determining the total support strength when the tunnel's maximum safe service life is known; determining the support parameters based on the total support strength, the support parameters including: anchor spacing, anchor row spacing, and shotcrete thickness. This application takes into account the timeliness of the continuous accumulation of strain in rock in expansive rock tunnels during their service life, establishes a functional relationship between support strength and service life, and uses a "service life"-oriented design concept to improve the safety, rationality, and economy of support design. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0072] in:

[0073] Figure 1 FIG. 1 is an application environment diagram of a method for designing support parameters for expansive rock tunnels in a metal mine taking service time into consideration in one embodiment;

[0074] Figure 2 A flow chart of a method for designing support parameters for expansive rock tunnels in a metal mine taking service time into consideration in one embodiment;

[0075] Figure 3 A numerical model diagram of an expansive rock tunnel in a metal mine according to one embodiment;

[0076] Figure 4 is a graph showing the relationship between the water absorption rate and the expansion rate of rock in one embodiment;

[0077] Figure 5 is a first relationship curve diagram in one embodiment;

[0078] Figure 6 is a functional relationship diagram between the total support strength and the maximum safe service life of the tunnel in one embodiment;

[0079] Figure 7 FIG. 1 is a structural block diagram of a computer device in one embodiment. DETAILED DESCRIPTION

[0080] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0081] When tunneling in deep or humid environments, metal mines often penetrate highly expansive rock formations. Due to their unique hygroscopic expansion properties, these rocks expand in volume during long-term contact with groundwater or humid air, leading to continuous deformation and contraction of the tunnel cross-section. As tunnels age, this expansion effect gradually accumulates. Failure to implement appropriate support measures can easily lead to tunnel instability, block fall, vault subsidence, and even collapse. Furthermore, as mining depth increases, tunnel temperatures rise significantly. Numerous studies have shown that high temperatures not only affect rock mechanical properties but also exacerbate moisture migration and hygroscopic expansion rates, creating a "temperature-humidity compound excitation" effect. Traditional models often fail to fully account for the combined effects of temperature on moisture migration and rock mass expansion-damage behavior, resulting in large prediction errors and poor applicability. In support design, the current industry generally determines anchor bolt or shotcrete parameters based on the initial excavation stress state. This ignores the time-dependent strain accumulation of expansive rock during its service life and fails to establish a functional relationship between support strength and service life. The lack of a design concept guided by "service life" often leads to a dilemma in support design: either "excessive redundancy" or "inadequate safety margins." To improve the safety, rationality, and economy of support design, a scientific, systematic, and practical support design method is urgently needed. To address the above technical issues, this application provides a method for designing support parameters for expansive rock tunnels in metal mines that takes service life into consideration.

[0082] Figure 1 This is an application environment diagram of a method for designing support parameters for expansive rock tunnels in a metal mine taking service time into consideration in an embodiment. Figure 1The method for designing support parameters for expansive rock tunnels in metal mines, taking service life into consideration, is applied to a system for designing support parameters for expansive rock tunnels in metal mines, taking service life into consideration. The system for designing support parameters for expansive rock tunnels in metal mines, taking service life into consideration, includes a terminal 110 and a server 120. Terminal 110 and server 120 are connected via a network. Terminal 110 can be a desktop terminal or a mobile terminal. The mobile terminal can be at least one of a mobile phone, a tablet computer, and a laptop computer. Server 120 can be implemented as a standalone server or a server cluster consisting of multiple servers. The terminal 110 is used to establish a relative humidity distribution equation and a relative temperature distribution equation inside the rock; the server 120 is used to determine the rock strain and rock stress based on the relative humidity distribution equation and the relative temperature distribution equation; obtain uniaxial tensile strength and compressive strength, and determine the tensile damage threshold and the shear damage threshold based on the uniaxial tensile strength, compressive strength and the rock stress; determine the damage variable based on the magnitude of the tensile damage threshold and the shear damage threshold, and update the rock strain based on the damage variable until the time expires; obtain the volume force and the total support strength, and determine the first relationship based on the rock strain and rock stress Curve, the first relationship curve is the relationship curve between the horizontal displacement convergence deformation of the rock and the total support strength; the limit width of the tunnel function failure, the non-pedestrian side width, the mine car width, and the pedestrian side width are obtained, and the tunnel limit convergence deformation standard value is determined according to the limit width of the tunnel function failure, the non-pedestrian side width, the mine car width, and the pedestrian side width; a functional relationship between the total support strength and the maximum safe service life of the tunnel is established according to the first relationship curve and the tunnel limit convergence deformation standard value; when the maximum safe service life of the tunnel is known, the total support strength is determined; and the support parameters are determined according to the total support strength.

[0083] like Figure 2 As shown, in one embodiment, a method for designing support parameters of expansion rock tunnels in metal mines taking into account service time is provided. This method can be applied to both terminals and servers. This embodiment uses the application to terminals as an example. Figure 1 As shown, this embodiment provides a method for designing support parameters of expansion rock tunnels in metal mines taking into account service life. In this embodiment, a typical expansion rock tunnel at the -480 level of a metal mine is used for support design. The design shape of the tunnel is a three-center arch with a width of 3.3 meters and a height of 3.3 meters. Figure 3 As shown; the method for designing support parameters of metal mine expansion rock tunnels considering service time provided in this application specifically includes the following steps:

[0084] S10: Establish the relative humidity distribution equation and relative temperature distribution equation inside the rock;

[0085] S20: determining rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation;

[0086] S30: Acquire uniaxial tensile strength and compressive strength, and determine a tensile damage threshold and a shear damage threshold according to the uniaxial tensile strength, compressive strength, and the rock stress;

[0087] S40: determining a damage variable according to the tensile damage threshold and the shear damage threshold, and updating the rock strain according to the damage variable until a time limit expires;

[0088] S50: Obtaining body force and total support strength, and determining a first relationship curve in combination with the rock strain and rock stress, wherein the first relationship curve is a relationship curve between rock horizontal displacement convergence deformation and the total support strength;

[0089] S60: Obtaining a maximum width of the tunnel at which function failure occurs, a width on the non-pedestrian side, a width of the mine car, and a width on the pedestrian side, and determining a maximum convergence deformation standard value of the tunnel according to the maximum width of the tunnel at which function failure occurs, the width on the non-pedestrian side, the width of the mine car, and the width on the pedestrian side;

[0090] S70: establishing a functional relationship between total support strength and maximum safe service life of the roadway based on the first relationship curve and the roadway limit convergence deformation standard value; determining the total support strength when the maximum safe service life of the roadway is known;

[0091] S80: Determine the support parameters according to the total support strength, where the support parameters include: anchor bolt spacing, anchor bolt row spacing, and shotcrete thickness.

[0092] This application takes into account the timeliness of the continuous accumulation of strain in expansive rock tunnels during their service life, establishes a functional relationship between support strength and service life, and uses the "service life"-oriented design concept to improve the safety, rationality and economy of support design.

[0093] In one embodiment, determining rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation in step S20 includes:

[0094] S201: Determine the relative humidity of the rock according to the relative humidity distribution equation;

[0095] S202: Determine the relative temperature of the rock according to the relative temperature distribution equation;

[0096] S203: determining rock strain according to the relative humidity increments corresponding to the relative humidity of the rock at different times, the relative temperature increments corresponding to the relative temperature of the rock at different times, and the rock mechanical state;

[0097] S204: Determine rock stress according to the rock strain;

[0098] Determining the tensile damage threshold and the shear damage threshold according to the uniaxial tensile strength, the compressive strength and the rock stress in step S30 includes:

[0099] S301: Determine a tensile damage threshold according to the uniaxial tensile strength and the maximum principal stress component in the rock stress;

[0100] S302: Determine a shear damage threshold according to the compressive strength and a minimum principal stress component, a maximum principal stress component, and an internal friction angle in the rock stress.

[0101] In one embodiment, determining the support parameter according to the total support strength in step S80 includes:

[0102] S801: Determine the anchor support strength according to the total support strength;

[0103] S802: Obtain anchor tensile strength and anchor diameter, and determine anchor spacing and anchor row spacing based on the anchor support strength, anchor tensile strength, and anchor diameter;

[0104] S803: Obtain anchor net support strength, and determine shotcrete support strength according to the total support strength, anchor rod support strength, and the anchor net support strength;

[0105] S804: Obtaining the excavation radius of the circular roadway tunnel and the initial compressive strength of the shotcrete; determining the thickness of the shotcrete according to the shotcrete support strength, the excavation radius of the circular roadway tunnel and the initial compressive strength of the shotcrete.

[0106] In one implementation, a multi-field coupled numerical model of rock temperature, humidity, and stress was developed to describe the expansion, deformation, and mechanical damage behavior of expansive rock in metal mines during service due to changes in ambient temperature and humidity. By combining unsteady-state temperature conduction, temperature-dependent humidity diffusion, temperature- and humidity-induced strain, and damage evolution, this model accurately simulates the multi-field coupled behavior of surrounding rock during long-term service.

[0107] When the relative humidity outside the surrounding rock is greater than that inside, the resulting humidity gradient triggers water diffusion. This diffusion process is controlled by the humidity distribution and follows the non-steady-state diffusion mechanism described by Fick's second law. When the rock's properties or temperature change, the rock's moisture diffusion capacity also changes. Moisture migration is no longer dominated by a constant diffusion coefficient, but instead incorporates a temperature-damage coupling factor. The modified relative humidity distribution equation within the surrounding rock is as follows:

[0108] (1)

[0109] (2)

[0110] Among them, H RH is the relative humidity of the rock; Is the gradient operator, which represents the vector composed of the partial derivatives of the multivariate function in each coordinate direction; K h (T,D) is the humidity diffusion coefficient, which is a function of temperature and damage, is the initial humidity diffusion coefficient. In the initial state, D is 0; is a constant; is the critical damage value, that is, when the damage is equal to or greater than The humidity diffusion coefficient suddenly increases to a constant value when ; t is time; x, y and z are the coordinates of each point in the rock; T is the rock temperature; T0 is the reference temperature; is the temperature sensitivity coefficient; is the partial derivative of rock relative humidity with respect to time; rock relative humidity can be obtained by formula (1) and formula (2);

[0111] Similarly, when the temperature in the tunnel is no longer stable, the temperature field inside the rock will also evolve dynamically with the diffusion of heat. The relative temperature distribution equation inside the surrounding rock is as follows:

[0112] (3)

[0113] Among them, T is the relative temperature of rock, c is the specific heat capacity of rock, k is the thermal conductivity of rock, ρ is the density of rock, t is time, is the gradient operator, is the partial derivative of the rock relative temperature with respect to time. Specifically, the rock relative temperature can be obtained by formula (3).

[0114] In one embodiment, when the temperature and humidity within the rock change, the rock expands under the influence of humidity and temperature. The total strain of the rock can be decomposed into three components: elastic strain increment, humidity-induced strain increment, and thermal expansion strain. The determination of rock strain in step S203 based on the relative humidity increment corresponding to the relative humidity of the rock at different times, the relative temperature increment corresponding to the relative temperature of the rock at different times, and the rock mechanical state is achieved using the following expression:

[0115] (4)

[0116] (5)

[0117] , (6)

[0118] (7)

[0119] in, is the hygroscopic expansion coefficient, H RH is the relative humidity, L is the rock expansion rate during the water absorption expansion test, is the expansion strain caused by moisture absorption of rock, is the increase in relative humidity, is the Kronecker function, is the thermal expansion strain, is the coefficient of thermal expansion, is the temperature increment, is the initial thermal expansion coefficient, D is the damage variable, is the critical damage value, is a constant value; is the strain caused by mechanical load, For rock strain.

[0120] In one embodiment, when the thermal expansion and hygroscopic expansion properties of rock are isotropic, the determination of rock stress according to the rock strain in step S204 is achieved by the following expression:

[0121] , i=1,2,3, j=1,2,3 (8)

[0122] = , i=j(9)

[0123] in, is the rock stress, which is a tensor; is the rock strain, is the volumetric strain, is the Lame elastic constant; G is the shear modulus, G=E / 2(1+ ), E is the elastic modulus, , and E are the elastic moduli of the undamaged material and the damaged material respectively, D is the damage variable, Refers to Poisson's ratio; is the Kronecker function; is the coefficient of hygroscopic expansion; is the relative humidity increment; H RH is the relative humidity of the rock; is the relative temperature increment, T is the relative temperature of the rock, is the coefficient of thermal expansion.

[0124] In one embodiment, the determining of the tensile damage threshold according to the uniaxial tensile strength and the maximum principal stress component in the rock stress in step S301; and the determining of the shear damage threshold according to the compressive strength and the minimum principal stress component, the maximum principal stress component, and the internal friction angle in the rock stress in step S302 are achieved by the following expressions:

[0125] (10)

[0126] (11)

[0127] in, is the tensile damage threshold; is the shear damage threshold; is the maximum principal stress component of rock stress; is the minimum principal stress component of rock stress; Uniaxial tensile strength; Compressive strength; is the internal friction angle;

[0128] The damage variable is determined according to the magnitude of the tensile damage threshold and the shear damage threshold by the following expression:

[0129] (12)

[0130] Where D is the damage variable; is the maximum tensile strain; is the compressive principal strain; is the maximum principal strain; is the minimum principal strain.

[0131] The acquisition of the body force and the total support strength in step 50 and the determination of the first relationship curve in combination with the rock strain and rock stress are achieved by the following expression:

[0132] (13)

[0133] (14)

[0134] , i=1,2,3, j=1,2,3 (15)

[0135] = , i=j(16)

[0136] In order to simulate the common tunnel support conditions in actual mining projects, the model further introduces the support force term as a component of the external force field to participate in the stress balance equation. Considering the support provided by the support system (such as anchors, spraying layers, steel frames, etc.) to the surrounding rock, its influence can be regarded as an equivalent external force density. The modified stress balance control equation is formula (14), is the rock stress, which is a tensor; is the rock strain, is the volumetric strain, is the Lame elastic constant; G is the shear modulus, G=E / 2(1+ ), E is the elastic modulus, , and E are the elastic moduli of the undamaged material and the damaged material respectively, D is the damage variable, Refers to Poisson's ratio; is the Kronecker function; is the coefficient of hygroscopic expansion; is the relative humidity increment; H RH is the relative humidity of the rock; is the relative temperature increment, T is the relative temperature of the rock, is the coefficient of thermal expansion; is the displacement component in the i direction, is the displacement component in the j direction, x i and is the spatial coordinate, is the gradient operator, is the rock stress, f is the body force, is the total support strength. The deformation of the expansive rock tunnel under the action of the rock was solved, and the time-dependent convergence deformation curve of the surrounding rock under different total support strengths was drawn. That is, the following equations can be obtained through formulas (13)-(16): Figure 5 The multiple first relationship curves shown are relationship curves between the horizontal displacement convergence deformation of rock and the total support strength P.

[0137] Based on the rock temperature-humidity-stress-damage multi-field coupled numerical model, the following Figure 3 The numerical model shown in Figure 1 is 30m × 30m in size and has a discrete grid of 17,472 cells. A vertical stress of 13.36MPa (equivalent to a burial depth of 509m) is applied to the top boundary to represent the deadweight of the overburden, and the support pressure is applied to the tunnel surface. The mechanical parameters of the model are the elastic modulus E of 0.3GPa and the compressive strength f c0 Take 24 MPa, internal friction angle 33°, Poisson's ratio v 0.3, homogeneity index m 4, and density ρ 2680 kg / m 3 , humidity diffusion coefficient K h(T,D) is 2×10 -10 m 2 / s, is the temperature sensitivity coefficient is 0.05 / K, specific heat capacity c is 950J / (kg·K), thermal conductivity k is 0.6W / (m·K), initial thermal expansion coefficient 9×10 -6 K -1 Determining the Hygroscopic Expansion Coefficient of Rock by Experiment The relationship with moisture content w is as follows Figure 4 As shown. Different support strengths are determined to be 0MPa, 0.3MPa, 0.6MPa, 0.9MPa, 1.2MPa, and 1.5MPa. Through numerical simulation, the deformation of the tunnel under different support strengths is obtained ( Figure 5 The curve in the figure shows that in the absence of support, the horizontal convergence deformation of the tunnel is 2.29 meters; while under higher support strength (such as 1.5MPa), the horizontal convergence deformation of the tunnel is effectively limited to below 1.27 meters.

[0138] For expansive rock tunnels, due to the obvious plastic expansion characteristics of the surrounding rock, sudden damage such as roof falls and spalling is usually not likely to occur. Large deformation of the surrounding rock becomes the most common and most engineering-impactful form of ground pressure. Therefore, when evaluating the stability of the tunnel, the tunnel convergence deformation can be used as an indicator to judge whether the tunnel function has failed. The tunnel cross-section is mainly composed of the mine car passage width, the pedestrian passage width and the non-pedestrian side width. In order to ensure that the operation function of the tunnel is not affected during long-term service, the "limit width of tunnel function failure" can be defined as On this basis, by introducing the safety factor F s , the maximum deformation allowed by the roadway can be calculated, that is, the roadway limit convergence deformation standard The determination of the tunnel limit convergence deformation standard value according to the tunnel function failure limit width, non-pedestrian side width, mine car width, and pedestrian side width in step S301 is achieved by the following expression:

[0139]

[0140] in, is the standard value of the tunnel's ultimate convergence deformation; F is the limit width of the tunnel function failure; s Is the safety factor, the commonly used range is 1.5<F s <2.0; a is the width on the non-pedestrian side; A1 is the width of the mine car; c is the width on the pedestrian side; Figure 5 As shown in the figure, the functional failure rebellion standard is the tunnel limit convergence deformation standard value ; By combining formula (17) and formula (14), the maximum safe service life of the roadway is determined , through the longest safe service life of the tunnel The total support strength P is obtained, and the longest safe service life of the known tunnel is t d Under the condition of , determine the total support strength P; the non-ferrous metal mine shaft engineering design code GB 50915-2013 requires that the width of the non-pedestrian side of the tunnel should not be less than 0.3m, and the width of the pedestrian side should not be less than 0.8m. The width of the mine car currently used in the mine is 1.1m, so the minimum width required for the passage of the mine car is 2.2m. The tunnel section width is 3.3m. When the shrinkage deformation on both sides of the tunnel reaches 1.1m, the tunnel function fails. Taking into account the safety factor F s is 1.5, and the criterion for determining tunnel function failure is determined to be 0.73m.

[0141] The obtained time-dependent convergence deformation curve is compared with the roadway limit convergence deformation standard. When the convergence deformation value of the roadway calculated by the numerical model is equal to the roadway limit convergence deformation standard, the corresponding time is the service life of the roadway. The time-dependent convergence deformation curve under different support strengths is compared with the roadway limit convergence deformation standard. Figure 6 As shown, the functional relationship between the total support strength and the maximum safe service life of the tunnel is established as follows:

[0142] (18)

[0143] Among them, t d is the maximum safe service life of the tunnel; P is the total support strength, The specific value is 23.80, The specific value is 3.23, The specific value is 0.41.

[0144] In one embodiment, the determination of the support parameter according to the total support strength in step S80 is implemented by the following expression:

[0145] (19)

[0146] (20)

[0147] (twenty one)

[0148] Among them, P is the total support strength; P b is the anchor support strength; P m is the anchor net support strength; P s is the support strength of shotcrete; is the initial compressive strength of shotcrete; R is the excavation radius of the circular roadway tunnel; is the thickness of shotcrete; d is the diameter of anchor rod; is the tensile strength of the anchor rod; L b,x is the anchor spacing; L b,y Anchor rod spacing.

[0149] Specifically, when the support strength provided by the anchor rod, anchor net and shotcrete is greater than or equal to the optimal support strength, the tunnel service time meets the design requirements. The calculation formula for the total support strength is as shown in formula (19). According to existing research, the anchor net support strength P provided by the anchor net is m The anchor support strength P provided by the anchor is fixed at 0.01 MPa. b It accounts for 60% of the total support strength, and the remaining support strength is provided by shotcrete.

[0150] In one embodiment, the anchor rod diameter used in the -480 horizontal expansive rock tunnel is 32 mm, the anchor rod tensile strength is 490 MPa, and the initial compressive strength of C20 shotcrete is 10 MPa. According to the above formula, the final support parameters are: anchor rod spacing 810 mm, row spacing 810 mm, and shotcrete thickness 75 mm.

[0151] Figure 7 FIG1 shows an internal structure diagram of a computer device in an embodiment. The computer device can be a terminal or a server. Figure 7 As shown, the computer device includes a processor, a memory and a network interface connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor may implement a method for designing support parameters for expansion rock tunnels in metal mines that takes into account service time. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor may implement a method for designing support parameters for expansion rock tunnels in metal mines that takes into account service time. It will be understood by those skilled in the art that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0152] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0153] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0154] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for designing support parameters for expansive rock tunnels in metal mines taking service time into consideration, characterized in that: The method comprises: Establish the relative humidity distribution equation and relative temperature distribution equation inside the rock; determining rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation; Obtaining uniaxial tensile strength and compressive strength, and determining a tensile damage threshold and a shear damage threshold based on the uniaxial tensile strength, compressive strength, and the rock stress; determining a damage variable according to the tensile damage threshold and the shear damage threshold, and updating the rock strain according to the damage variable until a time limit expires; Obtaining body force and total support strength, and determining a first relationship curve in combination with the rock strain and rock stress, wherein the first relationship curve is a relationship curve between rock horizontal displacement convergence deformation and the total support strength; Obtaining a maximum width of a tunnel at which a function fails, a width on a non-pedestrian side, a width of a mine car, and a width on a pedestrian side, and determining a standard value of a maximum convergence deformation of the tunnel based on the maximum width of a tunnel at which a function fails, the width on a non-pedestrian side, the width of a mine car, and the width on a pedestrian side; Establishing a functional relationship between the total support strength and the maximum safe service life of the roadway based on the first relationship curve and the roadway limit convergence deformation standard value; determining the total support strength when the maximum safe service life of the roadway is known; The support parameters are determined according to the total support strength, and the support parameters include: anchor bolt spacing, anchor bolt row spacing and shotcrete thickness.

2. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 1 is characterized in that: Determining rock strain and rock stress according to the relative humidity distribution equation and the relative temperature distribution equation includes: determining the relative humidity of the rock according to the relative humidity distribution equation; Determining the relative temperature of the rock according to the relative temperature distribution equation; determining rock strain according to the relative humidity increments corresponding to the relative humidity of the rock at different times, the relative temperature increments corresponding to the relative temperature of the rock at different times, and the rock mechanical state; determining rock stress based on the rock strain; Determining the tensile damage threshold and the shear damage threshold according to the uniaxial tensile strength, the compressive strength and the rock stress includes: determining a tensile damage threshold based on the uniaxial tensile strength and the maximum principal stress component in the rock stress; The shear damage threshold is determined according to the compressive strength and the minimum principal stress component, the maximum principal stress component and the internal friction angle in the rock stress.

3. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 1 is characterized in that: Determining the support parameters according to the total support strength includes: Determining the anchor support strength according to the total support strength; Obtaining the tensile strength and diameter of the anchor rods, and determining the anchor rod spacing and the anchor rod row spacing according to the anchor rod support strength, the tensile strength and the diameter of the anchor rods; Obtaining the anchor net support strength, and determining the shotcrete support strength according to the total support strength, the anchor rod support strength, and the anchor net support strength; The excavation radius of the circular roadway tunnel and the initial compressive strength of the shotcrete are obtained; and the thickness of the shotcrete is determined according to the excavation radius of the circular roadway tunnel and the initial compressive strength of the shotcrete.

4. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 1 is characterized in that: The relative humidity distribution equation is as follows: （1） Among them, H RH is the relative humidity of the rock; Is the gradient operator, which represents the vector composed of the partial derivatives of the multivariate function in each coordinate direction; K h (T,D) is the humidity diffusion coefficient, which is a function of temperature and damage, is the initial humidity diffusion coefficient. In the initial state, D is 0; is a constant; is the critical damage value, that is, when the damage is equal to or greater than The humidity diffusion coefficient suddenly increases to a constant value when ; t is time; x, y and z are the coordinates of each point in the rock; T is the rock temperature; T0 is the reference temperature; is the temperature sensitivity coefficient; is the partial derivative of rock relative humidity with respect to time; The relative temperature distribution equation is as follows: Among them, T is the relative temperature of rock, c is the specific heat capacity of rock, k is the thermal conductivity of rock, ρ is the density of rock, t is time, is the gradient operator, is the partial derivative of the rock relative temperature with respect to time.

5. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 2, characterized in that: The rock strain is determined according to the relative humidity increment corresponding to the relative humidity of the rock at different times, the relative temperature increment corresponding to the relative temperature of the rock at different times, and the rock mechanical state by the following expression: , in, is the hygroscopic expansion coefficient, H RH is the relative humidity, L is the rock expansion rate during the water absorption expansion test, is the expansion strain caused by moisture absorption of rock, is the increase in relative humidity, is the Kronecker function, is the thermal expansion strain, is the coefficient of thermal expansion, is the temperature increment, is the initial thermal expansion coefficient, D is the damage variable, is the critical damage value, is a constant value; is the strain caused by mechanical load, For rock strain.

6. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 5, characterized in that: The rock stress is determined according to the rock strain by the following expression: ,i=1,2,3,j=1,2,3 = ,i=j in, is the rock stress, which is a tensor; is the rock strain, is the volumetric strain, is the Lame elastic constant; G is the shear modulus, G=E / 2(1+ ), E is the elastic modulus, , and E are the elastic moduli of the undamaged material and the damaged material respectively, D is the damage variable, Refers to Poisson's ratio; is the Kronecker function; is the coefficient of hygroscopic expansion; is the relative humidity increment; H RH is the relative humidity of the rock; is the relative temperature increment, T is the relative temperature of the rock, is the coefficient of thermal expansion.

7. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 2, characterized in that: The tensile damage threshold is determined based on the uniaxial tensile strength and the maximum principal stress component in the rock stress; and the shear damage threshold is determined based on the compressive strength and the minimum principal stress component, the maximum principal stress component, and the internal friction angle in the rock stress by the following expressions: in, is the tensile damage threshold; is the shear damage threshold; is the maximum principal stress component of rock stress; is the minimum principal stress component of rock stress; Uniaxial tensile strength; Compressive strength; is the internal friction angle; The damage variable is determined according to the magnitude of the tensile damage threshold and the shear damage threshold by the following expression: Where D is the damage variable; is the maximum tensile strain; is the compressive principal strain; is the maximum principal strain; is the minimum principal strain.

8. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 7, characterized in that: The acquisition of the volume force and the total support strength and the determination of the first relationship curve in combination with the rock strain and rock stress are achieved through the following expression: ,i=1,2,3,j=1,2,3 = ,i=j in, is the rock stress, which is a tensor; is the rock strain, is the volumetric strain, is the Lame elastic constant; G is the shear modulus, G=E / 2(1+ ), E is the elastic modulus, , and E are the elastic moduli of the undamaged material and the damaged material respectively, D is the damage variable, Refers to Poisson's ratio; is the Kronecker function; is the coefficient of hygroscopic expansion; is the relative humidity increment; H RH is the relative humidity of the rock; is the relative temperature increment, T is the relative temperature of the rock, is the coefficient of thermal expansion; is the displacement component in the i direction, is the displacement component in the j direction, x i and is the spatial coordinate, is the gradient operator, is the rock stress, f is the body force, is the total support strength.

9. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 1, characterized in that: The determination of the tunnel limit convergence deformation standard value based on the tunnel function failure limit width, non-pedestrian side width, mine car width, and pedestrian side width is achieved by the following expression: in, is the standard value of the tunnel's ultimate convergence deformation; F is the limit width of the tunnel function failure; s is the safety factor; a is the width on the non-pedestrian side; A1 is the width of the mine car; c is the width on the pedestrian side; The functional relationship between the total support strength and the maximum safe service life of the tunnel is expressed as follows: Among them, T d is the maximum safe service life of the tunnel; P is the total support strength, 、 、 is a constant coefficient.

10. The method for designing support parameters of expansive rock tunnels in metal mines considering service time according to claim 3, characterized in that: The support parameter is determined according to the total support strength by the following expression: Among them, P is the total support strength; P b is the anchor support strength; P m is the anchor net support strength; P s is the support strength of shotcrete; is the initial compressive strength of shotcrete; R is the excavation radius of the circular roadway tunnel; is the thickness of shotcrete; d is the diameter of anchor rod; is the tensile strength of the anchor rod; L b,x is the anchor spacing; L b,y Anchor rod spacing.

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