A rockburst prevention and control method for NPR anchor energy absorption support

Abstract

The present application relates to the technical field of electronic digital data processing, and relates to a method for preventing and controlling rock bursts using an NPR anchor rod energy absorption support, comprising the following steps: Step S1, obtaining the dynamic parameters of the NPR anchor rod through a drop hammer test; Step S2, determining the selected stress control parameters of the surrounding rock through a rock burst excavation compensation model; Step S3, obtaining the rock burst energy parameters through a uniaxial compression test and a true triaxial rock burst test; Step S4, obtaining the energy parameters of a single NPR anchor rod through a dynamic impact tensile test; Step S5, obtaining the strength and energy coupling control parameters of the NPR anchor rod. The method for preventing and controlling rock bursts using an NPR anchor rod energy absorption support proposed in the present application has important application value. This method can scientifically and rationally design the anchor rod configuration and optimize the support scheme based on specific geological conditions and stress states, thereby effectively preventing and controlling rock bursts and improving the safety and economy of tunnel construction.

Description

Technical Field

[0001] The present application relates to the field of electronic digital data processing technology, and in particular to a method for preventing and controlling rock bursts using NPR anchor energy absorption support. Background Art

[0002] In deep tunnel construction, rockburst is a nonlinear dynamic phenomenon caused by the instantaneous release of large amounts of energy from the rock mass along the excavation unloading surface under high geostress conditions. This phenomenon poses significant challenges to construction safety and tunnel stability. Its essence lies in the sudden release of energy accumulated in the surrounding rock. The key to effective rockburst control lies in utilizing support systems to absorb the released energy and reduce the degree of energy accumulation. Traditional rockburst control methods often struggle to cope with the complex geological environment of deep tunnels, especially under high stress conditions. As an emerging support technology, NPR (Negative Poisson's Ratio) anchors offer excellent mechanical and energy absorption properties, particularly for dynamic hazards caused by high geostress in deep tunnels. However, in practical applications, the scientific and rational design of NPR anchors to effectively control rockburst remains challenging.

[0003] Therefore, a rockburst prevention and control method using highly prestressed NPR anchors for energy absorption support has significant application value. This method can scientifically and rationally design anchor configurations and optimize support schemes based on specific geological conditions and stress states, effectively preventing and controlling rockbursts and improving the safety and economic efficiency of tunnel construction. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a high prestressed NPR anchor energy absorption support rock burst prevention and control method. On the basis of traditional strength support design, the influence of dynamic load rock burst on support design is considered, and a strength-energy coupling two-level optimization rock burst control support design method based on dynamic characteristics is established. It can effectively reduce the risk of dynamic disasters in deep tunnels, ensure construction safety, and carry out efficient prevention and control design of rock burst problems caused by dynamic loads.

[0005] The present application relates to a method for preventing and controlling rock bursts using an NPR anchor rod energy-absorbing support. The improvement lies in that the method is characterized in that the rock burst prevention and control method comprises the following steps:

[0006] Step S1, obtaining the dynamic parameters of the NPR anchor through a drop hammer test;

[0007] Step S2, determining candidate stress control parameters of surrounding rock through rockburst excavation compensation model;

[0008] Step S3, obtaining rock burst energy parameters of the rock mass through uniaxial compression test and true triaxial rock burst test;

[0009] Step S4, obtaining energy parameters of a single NPR anchor through a dynamic impact tensile test;

[0010] Step S5, obtaining NPR anchor strength and energy coupling control parameters;

[0011] Step S5-1, obtaining NPR anchor strength control parameters through selected surrounding rock stress control parameters;

[0012] Step S5-2, obtaining NPR anchor energy control parameters through the rock mass rockburst energy parameters and the energy parameters of the single NPR anchor;

[0013] Step S5-3, obtaining the NPR anchor strength and energy coupling control parameters through the NPR anchor strength control parameters and the NPR anchor energy control parameters.

[0014] Preferably, step S1 includes: obtaining the dynamic parameters of the NPR anchor rod through a drop hammer test, and determining the maximum impact stress σ of the NPR anchor rod. max , and the tensile capacity L parameter of the NPR anchor are shown as follows:

[0015] ;

[0016] ;

[0017] Among them, A r is the cross-sectional area of ​​the NPR anchor; L r is the length of the NPR anchor; H0 is the critical impact height; H is the drop distance; A t It is the sum of the cross-sectional areas of the fastening nut and the sleeve; is the lower limit constant resistance of stick-slip motion of NPR anchor under static load condition; M is the mass of the drop weight; C is the propagation velocity of stress wave in the rod body of NPR anchor; ρ is the material density of the NPR anchor rod; I A is the impact coefficient; g is the acceleration of gravity; E is the elastic modulus of the NPR anchor; P0 is the constant resistance value of the NPR anchor.

[0018] Preferably, step S2, determining the selected stress control parameters of the surrounding rock using the rockburst excavation compensation model, includes the following steps:

[0019] Step S2-1, determining the first stress, second stress, and third stress of the rock mass to be tested in any direction at the engineering site by using a geostress testing method;

[0020] Step S2-2, determining the maximum principal stress, the intermediate principal stress, and the minimum principal stress of the rock mass to be measured based on the first stress, the second stress, and the third stress;

[0021] Step S2-3: Establishing a rockburst excavation compensation model based on the maximum principal stress, the intermediate principal stress, and the minimum principal stress, including: Q and the dynamic shear stress threshold τ of rockburst failure Q Obtain the strength curve of the rockburst excavation compensation model;

[0022] Among them, the dynamic normal stress threshold σ of rock burst damage Q As shown in the following formula:

[0023] ;

[0024] Among them, the dynamic shear stress threshold τ of rock burst damage Q As shown in the following formula:

[0025] ;

[0026] Among them, σ 1d is the maximum principal stress value at the time of rock burst, σ1 is the maximum principal stress, σ3 is the minimum principal stress, and σ p is the normal stress of rock mass static failure, τ p is the shear stress of static failure of rock mass.

[0027] Step S2-4: analyzing the relationship between the strength curve and the strength envelope in the rockburst excavation compensation model.

[0028] Preferably, step S2-4, analyzing the relationship between the strength curve and the strength envelope in the rockburst excavation compensation model, includes the following steps:

[0029] Step S2-4-1, setting different test stress control parameters according to different NPR anchor parameter groups;

[0030] Step S2-4-2: for each set of the test stress control parameters, input the test stress control parameters into the rock mass rockburst excavation compensation model to obtain a strength curve of the rock mass rockburst excavation compensation model;

[0031] Step S2-4-3, analyze the strength curve of the rock mass rock burst excavation compensation model corresponding to each set of the test stress control parameters; if the strength curve in the rock mass rock burst excavation compensation model does not exceed the strength envelope, the test stress control parameters are determined as the candidate stress control parameters for the surrounding rock.

[0032] Preferably, step S3, obtaining rockburst energy parameters of the rock mass through uniaxial compression test and true triaxial rockburst test, includes:

[0033] Step S3-1: preparing a first rock specimen from the rock mass to be tested, collected from the engineering site, and performing a uniaxial compression test on the first rock specimen to determine the uniaxial failure peak strength corresponding to the failure strain of the first rock specimen;

[0034] Step S3-2, plotting a uniaxial compression curve of the failure strain and uniaxial compression peak strength of the first rock mass specimen;

[0035] Step S3-3: preparing a second rock specimen from the rock mass to be tested collected from the engineering site, performing a true triaxial rockburst test on the second rock specimen, and obtaining the maximum principal stress of the second rock specimen at the time of rockburst occurrence;

[0036] Step S3-4: The peak strength corresponding to the failure strain of the first rock specimen and the maximum stress of the second rock specimen at the time of rockburst are brought into the rockburst excavation compensation model to determine the rockburst energy parameter E T , as shown below:

[0037] ;

[0038] Where r is the radius of the circular tunnel, ∆H is the maximum depth of the rockburst location from its free surface, σ c Uniaxial failure stress peak, ε c is the maximum strain value of uniaxial failure, σ 1c is the maximum principal stress of the second rock mass specimen at the moment of rockburst.

[0039] Preferably, step S4, obtaining energy parameters of a single NPR anchor through a dynamic impact tensile test, includes:

[0040] Step S4-1, determining the elastic deformation length, total deformation length, and impact load parameters of a single NPR anchor rod through a dynamic impact tensile test of the single NPR anchor rod;

[0041] Step S4-2, determining the total absorbed energy of the single NPR anchor rod by using the elastic deformation length, total deformation length, and impact load parameter value of the single NPR anchor rod;

[0042] The total absorbed energy of a single NPR anchor is determined by the following formula:

[0043] ;

[0044] ;

[0045] ;;

[0046] Where: P0 is the constant resistance value of NPR anchor; U cis the elastic deformation length of the NPR anchor rod; U0 is the total deformation length of the NPR anchor rod; k is the stiffness of a single NPR anchor rod; E Ⅰ is the elastic energy absorbed by a single NPR anchor; E Ⅱ is the energy absorbed by a single NPR anchor during the large deformation of the structure during yielding stage.

[0047] Preferably, step S5-1, obtaining the NPR anchor strength control parameters through the selected surrounding rock stress control parameters, includes:

[0048] According to the formula ,get:

[0049] ;

[0050] ;

[0051] F is the impact force of the NPR anchor drop test, b1 is the spacing between single NPR anchors in the stress control parameters, s1 is the row spacing between single NPR anchors in the stress control parameters, and n1 is the number of NPR anchors in the stress control parameters; Control stress for NPR anchors;

[0052] Step S5-2, obtaining NPR anchor energy control parameters based on the rockburst energy parameters and the energy parameters of the single NPR anchor, includes:

[0053] ;

[0054] in accordance with ,but ;

[0055] b2 is the spacing between single NPR anchor rods in the energy control parameters, s2 is the row spacing between single NPR anchor rods in the energy control parameters, and n2 is the number of NPR anchor rods in the energy control parameters;

[0056] Step S5-3, obtaining the NPR anchor strength and energy coupling control parameters through the NPR anchor strength control parameters and the NPR anchor energy control parameters, includes:

[0057] ;

[0058] ;

[0059] Where n is the number of NPR anchors for coupling control, taking the maximum value of n1 and n2; Pick and The minimum value in .

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] This method uses geostress testing to determine the stress state of the rock mass to be tested at the construction site, establishes a rockburst excavation compensation model, and determines candidate stress control parameters for the surrounding rock. This method also combines an NPR anchor drop hammer test to determine the NPR anchor strength control. Based on a surrounding rock energy theoretical model, this method determines the excess energy in the rock mass after a rockburst. Furthermore, it combines an NPR anchor dynamic impact tensile test to determine the energy the NPR anchor can absorb. Based on the NPR anchor strength and energy control, this method determines the rock mass strength and energy coupling for secondary optimization of NPR anchor parameters. This method effectively reduces the risk of rockbursts and ensures construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is one of the flow charts of the NPR anchor energy absorption support rockburst prevention and control method involved in the present invention;

[0063] Figure 2 This is the second flow chart of the NPR anchor energy absorption support rock burst prevention and control method involved in the present invention;

[0064] Figure 3 This is a schematic diagram of the ground stress test involved in the present invention;

[0065] Figure 4-1 A schematic diagram of simulating the original rock stress state during the rockburst loading process involved in the present invention;

[0066] Figure 4-2 A schematic diagram of the rockburst excavation compensation effect 1 according to the present invention;

[0067] Figure 4-3 A schematic diagram of the rockburst excavation compensation effect 2 according to the present invention;

[0068] Figure 5-1 A schematic diagram of a uniaxial compression curve according to the present invention;

[0069] Figure 5-2 A schematic diagram of a rockburst curve according to the present invention;

[0070] Figure 6 This is a schematic diagram of rock burst control in a deep tunnel according to the present invention;

[0071] Among them, 1. Tunnel; 2. Rock burst location; 3. Rock burst control area; 4. Surrounding rock. DETAILED DESCRIPTION

[0072] In order to better understand the present invention, the present invention is further described below with reference to the accompanying drawings and examples.

[0073] like Figure 1 and Figure 2As shown, the present application relates to a rockburst prevention and control method for NPR anchor energy absorption support, the improvement of which is that the rockburst prevention and control method includes the following steps:

[0074] Step S1: obtaining the dynamic parameters of the NPR anchor bolt through a drop hammer test.

[0075] Step S2: determining candidate stress control parameters of surrounding rock through a rockburst excavation compensation model.

[0076] Step S3: obtaining rock burst energy parameters of the rock mass through uniaxial compression test and true triaxial rock burst test.

[0077] Step S4: obtaining energy parameters of a single NPR anchor rod through a dynamic impact tensile test.

[0078] Step S5: Obtain NPR anchor strength and energy coupling control parameters.

[0079] The drop hammer test involved in step S1 is used to evaluate a material's impact resistance under dynamic loads. The drop hammer release mechanism is activated, causing the hammer to freely fall from a predetermined height, impacting the specimen. The instant the drop hammer impacts the specimen, it generates a significant impact force, causing the specimen to deform, crack, or break. After the impact test, parameters related to the material's impact resistance, such as impact absorption energy and fracture toughness, can be measured based on the test objectives and requirements.

[0080] Specifically, step S1 obtains the dynamic parameters of the NPR anchor rod through a drop hammer test and determines the maximum impact stress σ of the NPR anchor rod. max , that is, the dynamic parameter σ of the drop hammer test of a single NPR anchor max ; and the tensile capacity L parameter of the NPR anchor, as shown below:

[0081] ;

[0082] ;

[0083] Among them, A r and L r are the cross-sectional area and length of the NPR anchor respectively; H0 is the critical impact height; H is the drop distance; A t It is the sum of the cross-sectional areas of the fastening nut and the sleeve; is the lower limit constant resistance of stick-slip motion of NPR anchor under static load condition; M is the mass of the drop weight; C is the propagation velocity of stress wave in the rod body of NPR anchor; ρ is the material density of the NPR anchor rod; I A is the impact coefficient; g is the acceleration of gravity; E is the elastic modulus of the NPR anchor.

[0084] Step S2, determining candidate stress control parameters of surrounding rock using a rockburst excavation compensation model, includes the following steps:

[0085] Step S2-1: Determine the first stress, second stress, and third stress in any direction of the rock mass to be tested at the engineering site using a geostress testing method. Specifically, the geostress testing method is used to determine the first stress, second stress, and third stress in any direction of the rock mass to be tested at the engineering site. Typically, the three stresses in the X, Y, and Z directions are measured to perform a stress analysis in a three-dimensional rectangular coordinate system. A specific measurement method may be: perform a stress analysis based on external load conditions, calculate the magnitude and direction of the internal force on the rock mass to be tested, and then obtain the corresponding stresses in the three directions in the Cartesian coordinate system.

[0086] Step S2-2, based on the first stress, the second stress, and the third stress, the maximum principal stress, the intermediate principal stress, and the minimum principal stress of the rock mass to be measured are determined. Specifically, in implementation, the maximum principal stress, the intermediate principal stress, and the minimum principal stress of the rock mass to be measured can be determined based on the first stress, the second stress, and the third stress. The specific calculation method is: using the general stress in the Cartesian coordinate system, the normal stress and the tangential stress on the inclined surface are calculated. In the rock mass to be measured, the area of ​​the inclined surface is assumed to be dA, and the angle θ is an arbitrary angle (inclination angle of the inclined surface). The force analysis of the inclined surface is performed. Since stress multiplied by the corresponding area equals force, based on the equilibrium relationship, the resultant force in each direction is 0, and then the position of the principal plane is determined, and the maximum principal stress, the intermediate principal stress, and the minimum principal stress can be determined.

[0087] Specifically, such as Figure 3 As shown, OB is the plane in the Y direction; OA is the plane in the X direction; AB is the plane formed by the inclined plane AB, and the area of ​​the inclined plane SAB is dA, and the angle θ is the inclination angle of the inclined plane.

[0088] From the force analysis we can know that:

[0089] OB plane area S OB for: ;

[0090] OA plane area S OA for: ;

[0091] F on the oblique section x for: ;

[0092] Oblique section F y for: ;

[0093] F on the oblique section x The generated stress P x for: ;

[0094] F on the oblique section y The generated stress P y for: ;

[0095] Normal stress σ generated on the inclined section θ for: ;

[0096] Shear stress τ generated on the inclined section θ for: .

[0097] Among them, σ y is the normal stress in the y direction; σ x is the normal stress in the x direction; τ x is the shear stress in the x direction; τ y is the shear stress in the y direction; τ is the shear stress, τ x =τ y =τ.

[0098] Compare the normal stress σ generated on the above inclined section θ 、F on the inclined section x The generated stress P x , and F on the oblique section y The generated stress P y According to the size of , the maximum principal stress σ1, the intermediate principal stress σ2 and the minimum principal stress σ3 are selected.

[0099] Step S2-3: establishing a rockburst excavation compensation model based on the maximum principal stress, the intermediate principal stress, and the minimum principal stress.

[0100] Specifically, the establishment of rockburst excavation compensation model includes: based on the dynamic normal stress threshold σ of rockburst damage Q and the dynamic shear stress threshold τ of rockburst failure Q Obtain strength curves in rockburst excavation compensation models.

[0101] Among them, the dynamic normal stress (normal stress) threshold σ of rock burst failure Q As shown in the following formula:

[0102] ;

[0103] Dynamic shear stress threshold τ of rockburst failure Q As shown in the following formula:

[0104] ;

[0105] Among them, σ 1d is the maximum principal stress value at the time of rock burst, σ1 is the maximum principal stress, σ3 is the minimum principal stress, and σ pis the normal stress of rock mass static failure, τ p is the shear stress of static failure of rock mass.

[0106] Step S2-4, analyzing the relationship between the strength curve and the strength envelope in the rockburst excavation compensation model, includes the following steps:

[0107] Step S2-4-1, set several groups of test stress control parameters according to different NPR anchor parameters. Specifically, in the specific implementation, the NPR anchor parameters may include the spacing, row spacing and number of NPR anchors. The technician sets several groups of NPR anchor parameters to be tested according to different support stresses. Table 1 is an example table of support parameters to be tested provided in the embodiment of the present application, as shown in Table 1:

[0108]

[0109] Table 1

[0110] The test stress control parameters are shown in the following formula:

[0111] ;

[0112] F is the impact force of the NPR anchor drop test, b1 is the spacing of a single NPR anchor in the stress control parameter, s1 is the row spacing of a single NPR anchor in the stress control parameter, and n1 is the number of NPR anchors in the stress control parameter; NPR anchor control stress .

[0113] Step S2-4-2, for each set of test stress control parameters, the test stress control parameters are input into the rock mass rock burst excavation compensation model. Specifically, in the implementation, for each set of support parameters to be tested, the technicians input the support parameters to be tested into the rock mass rock burst excavation compensation model, and obtain the following: Figure 4-2 、 4-3 The rockburst excavation compensation model shown.

[0114] Step S2-4-3 analyzes the strength curve in the rockburst excavation compensation model corresponding to each set of the tested stress control parameters. If the strength curve in the rockburst excavation compensation model does not exceed the strength envelope, the tested stress control parameters are determined as candidate stress control parameters for the surrounding rock. Specifically, the strength envelope (Mohr-Coulomb failure envelope) is a line used in rock mechanics to describe the strength characteristics of rock. It is formed by connecting the failure points obtained in stress space through a series of strength tests (such as triaxial compression tests) under different stress states. The strength envelope represents the failure conditions of the rock material under different stress combinations. Specifically, when the stress state of the rock reaches a certain point on the strength envelope, the rock will fail. Different rocks have different strength envelopes, and their shape and position reflect the rock's inherent strength characteristics and its response to different stress states.

[0115] In the in-situ rock stress state diagram for rockburst loading simulation, the strength envelope can be used to determine the stability of the rock under a given in-situ stress state. If the in-situ stress state point lies within the strength envelope, the rock is stable and has not yet reached failure conditions. However, if the in-situ stress state point falls within or exceeds the strength envelope, it indicates that the rock may fail, posing a risk of instability such as rockburst.

[0116] In implementation, the rockburst excavation compensation model can simulate the stress changes of the rock mass to be tested, such as Figure 4-1 As shown in the figure, the rock mass to be tested is in a state of stress stability. There is a strength curve between every two stresses. The strength curve corresponding to the largest arc does not exceed the strength envelope (the oblique line in the figure), indicating that the stress is stable. If no support is provided after excavation, such as Figure 4-2 As shown in , the strength curve may move to the left and exceed the strength envelope above. After inputting the support parameters to be tested, it is equivalent to adding support components to the excavation surface of the rock mass to be tested, such as Figure 4-3 As shown, the strength curve will shift to the right and return to below the strength envelope, thus returning to a stress stable state.

[0117] Specifically, such as Figure 4-1 As shown in the figure, the stress state of the original rock before the rock burst occurs is simulated by stress loading. At this time, the rock burst loading stress curve does not exceed the upper strength envelope and is in a stress stable state. Figure 4-2 As shown in the figure, after the excavation of the chamber, the stress on the free surface is unloaded, and the minimum principal stress σ at the time of rock burst on the free surface is 3dReduced to 0, this process is the excavation unloading effect 1. The stress curve of the rock mass to be tested exceeds the strength envelope, which may lead to rock burst. However, if high prestress is applied to the free surface in time after excavation (such as setting support components to perform NPR support on the free surface to avoid rock burst), step S2-4 can be implemented, and the corresponding test stress control parameters are set according to different NPR support settings; and the test stress control parameters are input into the rock mass rock burst excavation compensation model, the free surface obtains stress compensation, and the minimum principal stress σ3 increases from 0 to σ 3d , get from 0 to σ 3d The minimum principal stress compensation in the direction of the excavation is called the excavation compensation effect1. Figure 4-3 As shown in the figure, after the excavation of the chamber, the stress on the free surface is unloaded, and the maximum principal stress σ at the time of rock burst on the free surface is 1d Increase to σ 1b This process is the excavation unloading effect 2. The stress curve of the rock mass to be tested exceeds the strength envelope, which may lead to rock burst. However, if high prestress is applied to the free surface in time after excavation (such as setting support components to perform NPR support on the free surface), that is, the corresponding test stress control parameters are set according to different NPR support settings; and the stress control parameters are input into the rock mass rock burst excavation compensation model, the free surface obtains stress compensation, and the maximum principal stress σ1 changes from σ 1b to σ 1d , obtained from σ 1b to σ 1d The maximum principal stress in the direction of the excavation is compensated. This process is called excavation compensation effect 2. The rock mass to be tested returns to a stress-stable state. At this point, the strength curve in the rockburst excavation compensation model does not exceed the strength envelope. The experimental stress control parameters used at this time are determined as the candidate stress control parameters for the surrounding rock.

[0118] Step S3, obtaining rock burst energy parameters through uniaxial compression test and true triaxial rock burst test, including:

[0119] In step S3-1, the rock mass to be tested collected from the engineering site is made into a first rock mass specimen, and a uniaxial compression test is performed on the first rock mass specimen to determine the uniaxial failure peak strength corresponding to the failure strain of the first rock mass specimen. Specifically, in the implementation, the technicians collect the rock mass to be tested from the engineering site and make the first rock mass specimen. For the uniaxial compression test, the first rock mass specimen can be made into a cylindrical specimen with a diameter of 100 mm and a height of 200 mm. The uniaxial compression test is to apply axial pressure to the first rock mass specimen and calculate the uniaxial failure stress peak σ according to the uniaxial compression formula of elastic mechanics. c and the maximum uniaxial failure strain ε c .

[0120] Step S3-2: draw a uniaxial compression curve of the failure strain and uniaxial compression peak strength of the first rock mass specimen.

[0121] Specifically, such as Figure 5-1 As shown in Figure 2, the abscissa is the strain value of the first rock specimen during the uniaxial compression test, and the ordinate is the stress value.

[0122] Step S3-3: Prepare a second rock specimen from the rock mass to be tested collected from the engineering site, conduct a true triaxial rockburst test on the second rock specimen, and obtain the maximum stress σ of the second rock specimen at the time of rockburst. 1c Specifically, during the implementation, technicians collected the rock mass to be tested from the project site and made a rectangular specimen with a side length of 100mm×100mm×200mm as the second rock mass specimen to conduct a true triaxial rockburst test. The second rock mass specimen was placed in the first stress, second stress and third stress states in order to simulate the excavation effect of the rock mass in the actual project and the excavation compensation effect after the addition of support components.

[0123] like Figure 5-2 As shown in Figure 2, the abscissa is the strain of the second rock specimen during the true triaxial rockburst test, and the ordinate is the stress.

[0124] In practice, since the failure strain of the uniaxial compression test is easy to measure, the rockburst strain in the true triaxial rockburst test is affected by the strains in the three stress directions, so the determined stress-strain curve cannot be expressed in a plane coordinate system. Therefore, in the embodiment of the present application, assuming that the failure strain of the first rock specimen is equal to the rockburst strain of the second rock specimen, the rockburst strain value of the second rock specimen can be obtained. At the same time, based on the maximum stress value of the second rock specimen at the time of rockburst occurrence obtained in the true triaxial rockburst test, the following can be obtained: Figure 5-2 The rockburst curve passing through the coordinate origin is shown in FIG. , wherein the abscissa is the rockburst strain value of the second rock mass specimen, that is, the failure strain value of the first rock mass specimen; and the ordinate is the maximum stress value obtained by the second rock mass specimen during the true triaxial rockburst test.

[0125] Step S3-4, the peak strength corresponding to the failure strain of the first rock specimen and the maximum stress of the second rock specimen at the time of rockburst are brought into the rockburst excavation compensation model to determine the rockburst energy parameters.

[0126] Specifically, such as Figure 6 As shown in the schematic diagram of rockburst control in a deep tunnel, assume that the radius of tunnel 1 is r, and the distance between rockburst location 2 and the tunnel wall is ∆H, which is the maximum depth from the rockburst location to the free surface. The depth of rockburst control zone 3 is 1.5 times the maximum depth from the rockburst location to the free surface. Surrounding rock 4 is outside rockburst control zone 3.

[0127] The rockburst energy parameters are:

[0128] ;

[0129] Where r is the radius of the circular tunnel, ∆H is the maximum depth of the rockburst location from the free surface, σ c Uniaxial failure stress peak, ε c is the maximum strain value of uniaxial failure, σ 1c is the maximum principal stress of the second rock mass specimen at the moment of rockburst.

[0130] Step S4, obtaining energy parameters of a single NPR anchor through a dynamic impact tensile test, including:

[0131] Step S4-1, determining the elastic deformation length, total deformation length, and impact load parameters of a single NPR anchor rod through a dynamic impact tensile test of the single NPR anchor rod;

[0132] Step S4-2, determining the total absorbed energy of the single NPR anchor rod by using the elastic deformation length, total deformation length, and impact load parameter value of the single NPR anchor rod;

[0133] The total absorbed energy of a single NPR anchor is determined by the following formula:

[0134] ;

[0135] ;

[0136] ;

[0137] Where: P0 is the constant resistance value of NPR anchor; U c is the elastic deformation length of the NPR anchor rod; U0 is the total deformation length of the NPR anchor rod; k is the stiffness of the NPR anchor rod; E Ⅰ is the elastic energy absorbed by the NPR anchor; E Ⅱ is the energy absorbed by the large deformation of the NPR anchor during the structural yield stage.

[0138] Preferably, in the above steps, steps S1 to S4 can be regarded as a first-level optimization, specifically referring to the initial selection of strength control parameters and energy control parameters in controlling rock burst in NPR anchor bolts.

[0139] Step S5, obtaining NPR anchor strength and energy coupling control parameters, including:

[0140] Step S5-1, obtaining NPR anchor strength control parameters through the selected surrounding rock stress control parameters, including:

[0141] According to the formula ,get:

[0142] ;

[0143] ;

[0144] F is the impact force of the NPR anchor drop test, b1 is the spacing between single NPR anchors in the stress control parameters, s1 is the row spacing between single NPR anchors in the stress control parameters, and n1 is the number of NPR anchors in the stress control parameters;

[0145] Step S5-2, obtaining NPR anchor energy control parameters based on the rockburst energy parameters and the energy parameters of the single NPR anchor, includes:

[0146] ;

[0147] in accordance with ,but ;

[0148] b2 is the spacing between single NPR anchor rods in the energy control parameters, s2 is the row spacing between single NPR anchor rods in the energy control parameters, and n2 is the number of NPR anchor rods in the energy control parameters;

[0149] Preferably, steps S5-1 and S5-2 can be considered as secondary optimization, specifically referring to the optimization of the NPR anchor strength and energy coupling control parameters. Step S5-3, obtaining the NPR anchor strength and energy coupling control parameters using the NPR anchor strength control parameters obtained in step S5-1 and the NPR anchor energy control parameters obtained in step S5-2, includes:

[0150] ;

[0151] ;

[0152] Where n is the number of NPR anchors for coupling control, taking the maximum value of n1 and n2; Pick and The minimum value in .

[0153] After the design is completed, a rockburst prevention and control design plan for deep tunnel projects is formulated and applied on-site. After implementation, monitoring and evaluation feedback is provided on the project site. This monitoring and evaluation feedback includes evaluation of surrounding rock deformation, structural stress, energy change, and blast pit depth.

[0154] The evaluation of surrounding rock deformation is to divide the surrounding rock into zones of crushing conditions through drilling and radar detection, and to measure the range of the surrounding rock loosening zone after the support is completed.

[0155] The structural stress evaluation is to install anchor dynamometers on the NPR anchors used for support, monitor the stress of the NPR anchors during and after construction, and compare and evaluate them with the ultimate load of the anchors.

[0156] Energy change evaluation is to evaluate the on-site energy change of NPR anchor control through microseismic monitoring equipment during tunnel excavation.

[0157] The blast pit depth evaluation is based on the area of ​​the cave wall damaged by the rockburst and the volume of the exploded rock mass to assess the scale of the rockburst disaster and thus evaluate the prevention and control effect of the NPR anchor.

[0158] This embodiment provides feedback optimization for the rockburst prevention and control design method for deep tunnel engineering through various monitoring and evaluation results.

[0159] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0160] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0161] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0162] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0163] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A method for preventing and controlling rock bursts by using an NPR anchor energy absorption support, characterized in that: The rockburst prevention and control method comprises the following steps: Step S1, obtaining the dynamic parameters of the NPR anchor through a drop hammer test; Step S2, determining candidate stress control parameters of surrounding rock through rockburst excavation compensation model; Step S3, obtaining rock burst energy parameters of the rock mass through uniaxial compression test and true triaxial rock burst test; Step S4, obtaining energy parameters of a single NPR anchor through a dynamic impact tensile test; Step S5, obtaining NPR anchor strength and energy coupling control parameters; Step S5-1, obtaining NPR anchor strength control parameters through selected surrounding rock stress control parameters; Step S5-2, obtaining NPR anchor energy control parameters through the rock mass rockburst energy parameters and the energy parameters of the single NPR anchor; Step S5-3, obtaining NPR anchor strength and energy coupling control parameters through NPR anchor strength control parameters and NPR anchor energy control parameters; Step S5-1, obtaining NPR anchor strength control parameters through the selected surrounding rock stress control parameters, including: According to the formula ,get: ； ； F is the impact force of the NPR anchor drop test, b1 is the spacing between single NPR anchors in the stress control parameters, s1 is the row spacing between single NPR anchors in the stress control parameters, and n1 is the number of NPR anchors in the stress control parameters; Control stress for NPR anchors; Step S5-2, obtaining NPR anchor energy control parameters based on the rockburst energy parameters and the energy parameters of the single NPR anchor, includes: ； in accordance with ,but ; b2 is the spacing between single NPR anchor rods in the energy control parameter, s2 is the row spacing between single NPR anchor rods in the energy control parameter, n2 is the number of NPR anchor rods in the energy control parameter; L is the stretching amount of NPR anchor rod; E T is the rockburst energy parameter; r is the radius of the circular tunnel; is the maximum depth of the rockburst location from its free surface; σ c Uniaxial failure stress peak; ε c is the maximum strain value of uniaxial failure; σ 1c is the maximum principal stress of the second rock mass specimen at the moment of rockburst; E s is the total absorbed energy of a single NPR anchor; P0 is the constant resistance value of the NPR anchor; U c is the elastic deformation length of the NPR anchor rod; U0 is the total deformation length of the NPR anchor rod; Step S5-3, obtaining the NPR anchor strength and energy coupling control parameters through the NPR anchor strength control parameters and the NPR anchor energy control parameters, includes: ； ； Where n is the number of NPR anchors for coupling control, taking the maximum value of n1 and n2; Pick and The minimum value in .

2. The NPR anchor energy absorption support rockburst prevention and control method according to claim 1, characterized in that: Step S1 includes: obtaining the dynamic parameters of the NPR anchor rod through a drop hammer test, and determining the maximum impact stress σ of the NPR anchor rod. max , and the tensile capacity L parameter of the NPR anchor are shown as follows: ； ； Among them, A r is the cross-sectional area of ​​the NPR anchor; L r is the length of the NPR anchor; H0 is the critical impact height; H is the drop distance; A t It is the sum of the cross-sectional areas of the fastening nut and the sleeve; is the lower limit constant resistance of stick-slip motion of NPR anchor under static load; M is the mass of the drop weight; C is the propagation velocity of stress wave in the NPR anchor rod; ρ is the material density of NPR anchor rod; I A is the impact coefficient; g is the acceleration of gravity; E is the elastic modulus of the NPR anchor; P0 is the constant resistance value of the NPR anchor.

3. The NPR anchor energy absorption support rockburst prevention and control method according to claim 1, characterized in that: Step S2, determining candidate stress control parameters of surrounding rock using a rockburst excavation compensation model, includes the following steps: Step S2-1, determining the first stress, second stress, and third stress of the rock mass to be tested in any direction at the engineering site by using a geostress testing method; Step S2-2, determining the maximum principal stress, the intermediate principal stress, and the minimum principal stress of the rock mass to be measured based on the first stress, the second stress, and the third stress; Step S2-3: Establishing a rockburst excavation compensation model based on the maximum principal stress, the intermediate principal stress, and the minimum principal stress, including: Q and the dynamic shear stress threshold τ of rockburst failure Q Obtain the strength curve of the rockburst excavation compensation model; Among them, the dynamic normal stress threshold σ of rock burst damage Q As shown in the following formula: ； Among them, the dynamic shear stress threshold τ of rock burst damage Q As shown in the following formula: ； Among them, σ 1d is the maximum principal stress value at the time of rock burst, σ1 is the maximum principal stress, σ3 is the minimum principal stress, and σ p is the normal stress of rock mass static failure, τ p is the shear stress of rock mass static failure; Step S2-4: analyzing the relationship between the strength curve and the strength envelope in the rockburst excavation compensation model.

4. The NPR anchor energy absorption support rockburst prevention and control method according to claim 3, characterized in that: Step S2-4, analyzing the relationship between the strength curve and the strength envelope in the rockburst excavation compensation model, includes the following steps: Step S2-4-1, setting different test stress control parameters according to different NPR anchor parameter groups; Step S2-4-2: for each set of the test stress control parameters, input the test stress control parameters into the rock mass rockburst excavation compensation model to obtain a strength curve of the rock mass rockburst excavation compensation model; Step S2-4-3, analyze the strength curve of the rock mass rock burst excavation compensation model corresponding to each set of the test stress control parameters; if the strength curve in the rock mass rock burst excavation compensation model does not exceed the strength envelope, the test stress control parameters are determined as the candidate stress control parameters for the surrounding rock.

5. The NPR anchor energy absorption support rockburst prevention and control method according to claim 1, characterized in that: Step S3, obtaining rock burst energy parameters through uniaxial compression test and true triaxial rock burst test, including: Step S3-1: preparing a first rock specimen from the rock mass to be tested, collected from the engineering site, and performing a uniaxial compression test on the first rock specimen to determine the uniaxial failure peak strength corresponding to the failure strain of the first rock specimen; Step S3-2, plotting a uniaxial compression curve of the failure strain and uniaxial compression peak strength of the first rock mass specimen; Step S3-3: preparing a second rock specimen from the rock mass to be tested collected from the engineering site, performing a true triaxial rockburst test on the second rock specimen, and obtaining the maximum principal stress of the second rock specimen at the time of rockburst occurrence; Step S3-4: The peak strength corresponding to the failure strain of the first rock specimen and the maximum stress of the second rock specimen at the time of rockburst are brought into the rockburst excavation compensation model to determine the rockburst energy parameter E T , as shown below: ； Where: r is the radius of the circular tunnel, is the maximum depth of the rockburst location from its free surface, σ c Uniaxial failure stress peak, ε c is the maximum strain value of uniaxial failure, σ 1c is the maximum principal stress of the second rock mass specimen at the moment of rockburst.

6. The NPR anchor energy absorption support rockburst prevention and control method according to claim 1, characterized in that: Step S4, obtaining energy parameters of a single NPR anchor through a dynamic impact tensile test, including: Step S4-1, determining the elastic deformation length, total deformation length, and impact load parameters of a single NPR anchor rod through a dynamic impact tensile test of the single NPR anchor rod; Step S4-2, determining the total absorbed energy of the single NPR anchor rod by using the elastic deformation length, total deformation length, and impact load parameter value of the single NPR anchor rod; The total absorbed energy E of a single NPR anchor s Determine using the following formula: ； ； ； Where: P0 is the constant resistance value of NPR anchor; U c is the elastic deformation length of the NPR anchor rod; U0 is the total deformation length of the NPR anchor rod; k is the stiffness of a single NPR anchor rod; E Ⅰ is the elastic energy absorbed by a single NPR anchor; E Ⅱ is the energy absorbed by a single NPR anchor during the large deformation of the structure during yielding stage.

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