Establishment method of high side wall aging deformation model considering bedding surrounding rock damage

Abstract

The invention discloses a method for establishing a high side wall aging deformation model considering bedding surrounding rock damage, and the method comprises the steps: obtaining a first coupling damage variable considering blasting damage and dry-wet cycle damage, and obtaining a second coupling damage variable comprehensively considering blasting damage, dry-wet cycle damage and continuous load damage; establishing an improved viscoelastic-plastic model considering blasting damage variables and dry-wet cycle damage; and completing the establishment of the high side wall aging deformation model considering the bedding surrounding rock damage. The model established by the invention not only can describe the rheological property of the bedding surrounding rock in the construction process, but also can describe the damage to the rheological property caused by blasting, dry-wet cycle and load in the construction process, and by improving the original viscoelastic plastic model, the rheological property of the bedding surrounding rock in the construction process can be described. The obtained improved viscoelastic-plastic model can better describe anisotropic characteristics of jointed slate, and has important guiding significance for long-term stability and safety of a high side wall in the blasting construction process of a subway.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a method for establishing a high side wall time-dependent deformation model taking into account damage to bedding surrounding rock. Background Art

[0002] During the excavation of the main body of the lower part of the subway station, partial excavation is required due to the large excavation section, and the side walls of the station are exposed for a long time. The surrounding rocks of the side walls on both sides of the station are frequently disturbed by blasting loads, with special stress states and significant cumulative damage effects. The side walls of the station have been exposed for a long time, and will be degraded by the dry-wet cycle of water on the surrounding rocks during construction. The dry-wet cycle is one of the most common water-rock interactions, and the deterioration of the surrounding rocks by the dry-wet cycle cannot be ignored. At the same time, jointed slate has certain rheological properties. When analyzing the structure of the lower side wall of the station, the long-term construction safety of the side wall is particularly prominent, and its time-varying behavior needs to be fully considered. However, the traditional creep model can only describe the rheological properties during construction, but cannot describe the damage caused by blasting, dry-wet cycles and loads on the rheological properties during construction. At the same time, it cannot describe the anisotropic characteristics of jointed slate. Summary of the invention

[0003] The invention discloses a method for establishing a high side wall time-dependent deformation model taking into account the damage of bedding surrounding rock, so as to overcome the above technical problems.

[0004] In order to achieve the above object, the technical solution of the present invention is:

[0005] A method for establishing a time-dependent deformation model of a high side wall considering damage to bedding surrounding rock comprises the following steps:

[0006] S1: Obtain the blasting damage variable D used to characterize the degree of weakening of the mechanical properties of the layered rock mass caused by blasting r , the dry-wet cycle damage variable D used to characterize the weakening degree of mechanical properties of layered rock mass caused by dry-wet cycles s and the continuous load damage variable D used to characterize the weakening degree of mechanical properties of layered rock mass caused by load c ;

[0007] S2: According to the blasting damage variable D r , dry-wet cycle damage variable D s , obtain the first coupled damage variable considering blasting damage and dry-wet cycle damage, and according to the continuous load damage variable D c , get the second coupling damage variable D z ; The second coupled damage variable is a damage variable that comprehensively considers blasting damage, dry-wet cycle damage, and continuous load damage;

[0008] S3: Based on the second coupled damage variable and the first coupled damage variable, an improved viscoelastic-plastic model considering blasting damage variables and dry-wet cycle damage is established to complete the establishment of a high side wall time-dependent deformation model considering bedding surrounding rock damage;

[0009] The improved viscoelastic-plastic model is to replace the plastic body in the original viscoelastic-plastic model with the plastic body in the improved ubiquitous joint model;

[0010] The elastic phase bulk modulus G0, the viscoelastic phase bulk modulus G1, the elastic phase viscosity coefficient η0, and the viscoelastic phase viscosity coefficient η1 in the improved viscoelastic-plastic model are all parameters related to the first coupled damage variable; the viscosity coefficient η2 of the viscoplastic body in the improved viscoelastic-plastic model is related to the second coupled damage variable D z Related parameters.

[0011] Beneficial effect: The method for establishing a time-dependent deformation model of a high side wall considering damage to the layered surrounding rock of the present invention establishes an improved viscoelastic-plastic model considering blasting damage variables and dry-wet cycle damage by obtaining a first coupled damage variable considering blasting damage and dry-wet cycle damage, and a second coupled damage variable comprehensively considering blasting damage, dry-wet cycle damage and continuous load damage; so as to complete the establishment of a time-dependent deformation model of a high side wall considering damage to the layered surrounding rock. The model established by the present invention can not only describe the rheological properties of the layered surrounding rock during the construction process, but also describe the damage to the rheological properties caused by blasting, dry-wet cycles and loads during the construction process. By improving the original viscoelastic-plastic model, the improved viscoelastic-plastic model obtained can better describe the anisotropic characteristics of jointed slate, which has important guiding significance for the long-term stability and safety of the high side wall during the blasting construction of the subway. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0013] Figure 1 A flow chart of a method for establishing a high side wall aging phenotype model taking into account bedding surrounding rock damage according to the present invention;

[0014] Figure 2 Schematic diagram of the spatial relationship between the local coordinates of the layered weak plane and the layer and the reference plane in an embodiment of the present invention;

[0015] Figure 3Schematic diagram of an improved viscoelastic-plastic model in an embodiment of the present invention;

[0016] Figure 4a Schematic diagram of a slate model at a 30° layered weak plane angle in an embodiment of the present invention

[0017] Figure 4b It is a schematic diagram comparing the creep curve test value and the calculated value of slate at a 30° layered weak plane angle in an embodiment of the present invention;

[0018] Figure 5 It is a schematic diagram of a calculation model for station excavation under blasting in an embodiment of the present invention;

[0019] Figure 6 Schematic diagram of a three-dimensional numerical calculation model of a station in an embodiment of the present invention;

[0020] Figure 7 It is a schematic diagram of the horizontal displacement curve of the side wall under different blasting times in an embodiment of the present invention;

[0021] Figure 8 It is a schematic diagram of the variation of the displacement of the side wall with the number of dry-wet cycles in an embodiment of the present invention;

[0022] Fig. 9 Schematic diagram of creep deformation curve of side wall at different creep times in an embodiment of the present invention;

[0023] Fig.10 It is a schematic diagram comparing the long-term monitoring result of the side wall displacement and the simulation result in the embodiment of the present invention;

[0024] Fig.11 It is a schematic diagram for comparing the calculation results of the models using different damage variables in the embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] This embodiment introduces a method for establishing a high side wall time-dependent deformation model considering the damage of bedding surrounding rock. Figure 1 As shown, the following steps are included:

[0027] S1: Obtain the blasting damage variable D used to characterize the degree of weakening of the mechanical properties of the layered rock mass caused by blasting r, the dry-wet cycle damage variable D used to characterize the weakening degree of mechanical properties of layered rock mass caused by dry-wet cycles s and the continuous load damage variable D used to characterize the weakening degree of mechanical properties of layered rock mass caused by load c ;

[0028] Preferably, the blasting damage variable D r Get as follows:

[0029] Specifically, in the related research on rock mass acoustic wave testing, the change of sound velocity is usually used to characterize the damage value of the rock mass. Within a certain blasting range, based on the change of rock mass sound velocity, the relationship between the rock mass damage degree and the sound velocity reduction rate η can be established, and then the blasting damage variable D can be obtained. r :

[0030]

[0031] Where v0 is the acoustic wave velocity of the rock mass before blasting; v is the acoustic wave velocity of the rock mass after blasting; η is the rate of decrease of acoustic velocity. r is the blasting damage variable;

[0032] Specifically, in one embodiment of the present invention, based on the actual blasting monitoring data of the station, the blasting damage function is determined as:

[0033]

[0034] Where N is the number of blasting times;

[0035] Preferably, the dry-wet cycle damage variable D s Get as follows:

[0036] Specifically, this embodiment considers the damage caused by dry-wet cycles to jointed slate, and obtains the following through the porosity and longitudinal wave velocity of the layered rock mass:

[0037]

[0038] Where: D s is the dry-wet cycle damage variable; n is the porosity of the stratified rock mass before the dry-wet cycle; n0 is the porosity after the dry-wet cycle; v s represents the longitudinal wave velocity before the dry-wet cycle; v s ′ represents the longitudinal wave velocity after the dry-wet cycle;

[0039] Specifically, in one embodiment of the present invention, the dry-wet cycle damage is determined based on the indoor test results as:

[0040] D S =0.11429(0.16827 n' ) Where n' represents the number of dry-wet cycles. Preferably, the continuous damage variable D c The acquisition method is as follows:

[0041] Specifically, when the applied load reaches or exceeds a certain stress level, damage will occur inside the stratified rock mass. The damage degree in the deceleration creep stage and the stable creep stage is relatively small. This embodiment only considers the damage caused by the stress in the accelerated creep stage, and obtains the damage D of the stratified rock mass in the accelerated creep process. c The negative exponential function relationship with time is as follows:

[0042] D c =1-e -λt (3)

[0043] Where: λ is the aging creep parameter; t is time; D c is the continuous load damage variable of the layered rock mass during the accelerated creep process.

[0044] S2: According to the blasting damage variable D r , dry-wet cycle damage variable D s , continuous load damage variable D c , get the coupling damage variable D z ;

[0045] Specifically, during the excavation process, the high side wall of the station will be exposed for a long time due to the long excavation period. The rock mass will be damaged by the aforementioned dry-wet cycle, cyclic blasting and load damage under the long-term action of the load. This embodiment couples multiple damages to analyze the stability of the rock mass under the influence of multiple factors.

[0046] Preferably, the coupling damage variable D z The acquisition method is as follows:

[0047] First, consider the blasting damage variable D r and dry-wet cycle damage variable D s The first coupled damage variable under is as follows:

[0048] D r / s =D r +D s -D r D s (4)

[0049] Where: D r / s It is the first coupled damage variable considering blasting damage variable and dry-wet cycle damage variable;

[0050] Then the second coupling damage variable that comprehensively considers the first coupling damage variable and the continuous load damage variable is obtained as:

[0051]

[0052] Specifically, in this embodiment, according to the theory of continuous damage mechanics, the expression of the relationship between the real stress and the effective stress of the damaged material is:

[0053]

[0054] Where: is the effective stress; σ is the true stress; D z The damage factor.

[0055] According to the Lemaitre strain equivalence principle, the strain generated in the effective stress space is:

[0056]

[0057] Where: ε is the strain tensor; E0 is the initial elastic modulus.

[0058] Substituting equation (7) into equation (6), we can obtain the stress-strain relationship represented by the coupled damage function:

[0059] σ=(1-D z )E0ε (8)

[0060] S3: According to the second coupling damage variable D z and the first coupled damage variable, to establish an improved viscoelastic-plastic model considering blasting damage variables and dry-wet cycle damage;

[0061] The improved viscoelastic-plastic model is to replace the plastic body in the original viscoelastic-plastic model with the plastic body in the improved ubiquitous joint model;

[0062] The elastic phase bulk modulus G0, the viscoelastic phase bulk modulus G1, the elastic phase viscosity coefficient η0, and the viscoelastic phase viscosity coefficient η1 in the improved viscoelastic-plastic model are all parameters related to the first coupled damage variable; the viscosity coefficient η2 of the viscoplastic body in the improved viscoelastic-plastic model is related to the second coupled damage variable D z Related parameters;

[0063] Specifically, the improved viscoelastic-plastic model of this embodiment takes into account the influence of the damage variables of blasting-wet-dry-load coupling on the creep parameters, and replaces the plastic body in the original viscoelastic-plastic model with the plastic body of the joint model. Therefore, the improved viscoelastic-plastic model can not only express the creep characteristics of the matrix of the stratified rock mass, but also consider the influence of the weak surface of the stratification on the rock. At the same time, since the influence of coupled damage is taken into account, it can also reflect the influence of the combined effects of blasting, wet-dry cycles and loads on the stratified rock mass.

[0064] Specifically, this embodiment takes into account the anisotropic characteristics of jointed slate, introduces a transversely isotropic body in the elastic stage, adopts a diffuse joint model in the plastic stage, and establishes an improved diffuse joint elastic-plastic model.

[0065] Preferably, the improved ubiquitous joint model is established as follows:

[0066] Specifically, layered anisotropic rock mass is isotropic in the x'y' plane parallel to the plane, while the z' direction perpendicular to the plane is an elastic direction different from the plane. According to engineering geological practices, the strike, dip and inclination of the plane are usually used to describe the attitude of the plane. Therefore, the local coordinate system Ox'y'z' is defined as: z' is the normal direction of the plane, and the x' axis and y' axis are respectively along the dip and strike of the plane. At the same time, the overall coordinate system is a rectangular coordinate system Oxyz, and the x-axis, y-axis and z-axis are respectively the dip, strike and normal directions of the plane in the overall coordinate system.

[0067] S31: Based on the elastic theory, the relationship between stress and strain in the plane parallel to the layered anisotropic rock mass and the relationship between stress and strain in the plane perpendicular to the layered anisotropic rock mass are established as follows:

[0068]

[0069] Where: ε′ x represents the x-direction strain in the global coordinate system; ε′ y represents the y-direction strain in the global coordinate system; ε′ z represents the z-direction strain in the global coordinate system; σ′ x represents the stress in the x direction in the global coordinate system; σ′ y represents the stress in the y direction in the global coordinate system; σ′ z represents the stress in the z direction in the global coordinate system; γ′ xy represents the shear strain in the xy direction in the global coordinate system; γ′ yz represents the shear strain in the yz direction in the global coordinate system; γ′ xz represents the shear strain in the xz direction in the global coordinate system; τ xy represents the shear stress in the xy direction in the global coordinate system; τ yz represents the shear stress in the yz direction in the global coordinate system; τ xz represents the shear stress in the xz direction in the global coordinate system; E1, μ1, G1 represent the elastic modulus, Poisson's ratio and shear modulus parallel to the layer of the layered anisotropic rock mass, respectively; E2, μ2, G2 represent the elastic modulus, Poisson's ratio and shear modulus normal to the layer of the layered anisotropic rock mass, respectively;

[0070] S32: The relationship between stress and strain in the plane parallel to the layered anisotropic rock mass and the relationship between stress and strain in the plane perpendicular to the layered anisotropic rock mass are expressed by a matrix as follows:

[0071] {σ'}=[M e ']{ε'} (10)

[0072] Where: [M e '] is the elastic matrix of the layered anisotropic medium in the layered normal coordinate system; {σ′} represents the stress in the local coordinate system; {ε′} represents the strain in the local coordinate system;

[0073] According to the stress {σ'} and {ε'} strain relationship of the layer and its normal, the elastic matrix of the layered anisotropy in the local coordinate system Ox'y'z' can be obtained as follows:

[0074]

[0075] Where:

[0076] A1, A2, and A3 are all intermediate calculation parameters; p represents the ratio of the elastic modulus E1 of the plane parallel to the layered anisotropic rock mass to the elastic modulus E2 of the plane normal to the layered anisotropic rock mass; m represents the ratio of the Poisson's ratio μ1 of the plane parallel to the layered anisotropic rock mass to the Poisson's ratio μ2 of the plane normal to the layered anisotropic rock mass;

[0077] Specifically, in the calculation process, for the convenience of calculation, the elastic matrix [M e ']Convert to the global coordinate system.

[0078] S33: Set the global coordinate system to the rectangular coordinate system Oxyz, convert the global coordinate system into the local coordinate system Ox'y'z', set a i ,b i ,c i (i=1,2,3) are the direction cosines of x',y',z' axes respectively, and the coordinate transformation matrix [Q] is expressed as:

[0079]

[0080] Where: [Q] represents the coordinate transformation matrix; a1 represents the direction cosines between the x' axis and the x axis; a2 represents the direction cosines between the y' axis and the x axis; a3 represents the direction cosines between the z' axis and the x axis; b1 represents the direction cosines between the x' axis and the y axis; b2 represents the direction cosines between the y' axis and the y axis; b3 represents the direction cosines between the z' axis and the y axis; c1 represents the direction cosines between the x' axis and the z axis; c2 represents the direction cosines between the y' axis and the z axis; c3 represents the direction cosines between the z' axis and the z axis;

[0081] The direction cosines in the coordinate transformation matrix [Q] are expressed by the azimuth of the rock layer, and the inclination and dip angle of the layer are α and β respectively. The spatial relationship between the layer and the reference plane is as follows: Figure 2 shown.

[0082] From this we can get:

[0083]

[0084] Where: α represents the inclination of the layer; β represents the dip angle of the layer;

[0085] S35: The stress transformation matrix from the global coordinate system to the local coordinate system is:

[0086]

[0087] Where: [L] represents the stress transformation matrix from the global coordinate system to the local coordinate system;

[0088] Then the conversion relationship between the stress {σ} in the global coordinate system and the stress {σ'} in the local coordinate system is as follows:

[0089] {σ′}=[L]{σ}

[0090] The transformation relationship between the strain {ε} in the global coordinate system and the strain {ε'} in the local coordinate system is as follows:

[0091] {ε′}=[L]{ε} (15)

[0092] S36: After sorting, the stress in the overall coordinate system is obtained as follows:

[0093] {σ}=[L] T [M' e ][L]{ε} (16)

[0094] Where: [L] T represents the transpose of [L];

[0095] Then, by comparing the stress expressions in the global coordinate system and the local coordinate system, the elastic matrix in the global coordinate system is obtained as follows:

[0096] [M e ]=[L] T [M′ e ][L] (17)

[0097] Among them, the elastic matrix in the global coordinate system obtained by the stress transformation matrix [L] is expressed as:

[0098]

[0099] Where: M 11 、M 16 、M 61 、M 66 are all intermediate calculation parameters, indicating [M e ];

[0100] Specifically, considering that the jointed slate rock has certain anisotropy (transverse isotropy) and creep characteristics, this embodiment combines the viscoelastic-plastic model with the improved diffuse joint model to establish an improved viscoelastic-plastic model, and converts the improved viscoelastic-plastic model into a differential form to achieve software implementation of the improved viscoelastic-plastic model, as follows:

[0101] Specifically, this embodiment derives the differential form of the improved viscoelastic-plastic model for establishing the first coupled damage variable considering the blasting damage variable and the dry-wet cycle damage variable, and carries out secondary development to realize the software implementation of the improved viscoelastic-plastic model, and obtain the calculation results of the model, including the displacement and stress of the station side wall during the construction process. This can realize the evaluation of the long-term construction safety of the station side wall, and can assist on-site construction personnel in establishing a long-term stability support structure for the large-span station side wall.

[0102] Specifically, the three-dimensional creep model considering damage can simulate the viscoelastic-plastic mechanical properties of the stratified rock mass, that is, creep occurs on the matrix of the stratified weak surface stratified rock mass, and the plasticity follows the yield criterion of the stratified weak surface. The model is developed based on the viscoelastic-plastic model and the improved stratified weak surface model. On the basis of the viscoelastic-plastic model, the model considers the yield effect of the joint weak surface, and the yield can occur in the matrix or stratified weak surface of the stratified rock mass.

[0103] Based on the viscoelastic-plastic model, this embodiment introduces the layered weak plane model and considers the influence of blasting and dry-wet cycle damage, and establishes a layered weak plane creep model considering blasting-dry-wet cycle damage. Figure 2 As shown. Dr / s and Dz are used as coefficients related to the bulk modulus G0 of the elastic stage, the bulk modulus G1 of the viscoelastic stage, the viscosity coefficient η0 of the elastic stage, the viscosity coefficient η1 of the viscoelastic stage, and the viscosity coefficient η2 of the viscoplastic body in the improved viscoelastic-plastic model, as shown in Figure 3As shown, F in the figure represents the improved diffuse joint model established in this embodiment.

[0104] Preferably, the improved viscoelastic-plastic model is converted into a differential form as follows:

[0105] Total strain e of creep damage model ij It consists of three parts, namely the strain of the damaged elastic element Damage strain of viscoelastic body Damage strain of viscoplastic body The expression is:

[0106]

[0107] Where: e ij is the total strain of the creep damage model; is the strain that damages the elastic element; is the strain that damages the viscoelastic body; is the strain that damages the viscoplastic body;

[0108] First, for the damaged elastic element, it can be obtained:

[0109]

[0110] Where: S ij represents the stress deviator; G0 represents the bulk modulus; D r / s It is the first coupled damage variable considering blasting damage variable and dry-wet cycle damage variable;

[0111] The above equation can be written as:

[0112]

[0113] in:

[0114]

[0115] In the formula, represents the updated deviatoric stress tensor; Δt represents the time increment; represents the updated strain deviator; represents the old value of the stress deviator in one time increment; represents the new value of the stress deviator in one time increment; is the old value of the strain deviator; is the new value of the strain deviator.

[0116] At the same time, for the damaged viscoelastic body, the deviatoric stress of the damaged viscoelastic body is composed of two parts: the spring and the viscoelastic pot, namely:

[0117]

[0118] Where: It represents the strain difference of the damaged viscoelastic body; represents the strain that damages the viscoelastic body;

[0119] Substituting equation (20) and equation (21) into equation (23), we can obtain:

[0120]

[0121] in,

[0122]

[0123] Combining equation (20) and equation (21), we can obtain:

[0124]

[0125]

[0126]

[0127] Where: represents the strain of the initial damaged viscoelastic body; Δe ij It represents the variation value; Represents the strain difference of the damaged viscoplastic body; represents the strain difference in the viscoelastic stage; represents the old value of the stress deviator in a time increment; A, B, a, b are all intermediate calculation parameters; η1 represents the viscosity coefficient in the viscoelastic stage; G1 represents the bulk modulus in the viscoelastic stage;

[0128] The characteristic expression of volume is:

[0129]

[0130] Where: represents the new value of the viscoelastic body stress; represents the old value of viscoelastic stress; K0 represents the bulk modulus; Δe vol represents the total strain rate; represents the volumetric strain rate of a viscoplastic body; represents the volumetric strain rate of the elastic body;

[0131] Therefore, the spherical strain of the viscoelastic body is obtained as follows:

[0132]

[0133]

[0134] Where: represents the spherical strain of the damaged viscoelastic body; C and F are both intermediate calculation parameters; K1 represents the bulk modulus of the viscoelastic body; The strain representing the initial strain of the damaged viscoelastic body;

[0135] Finally, for a viscoplastic body, the viscoplastic strain rate deviator is:

[0136]

[0137] Where: g ∞ is the long-term yield potential function; is the deviator of the volumetric strain rate of the viscoplastic body, that is:

[0138]

[0139] <F ∞ > is the switch function, which is expressed as follows:

[0140]

[0141] In the formula, represents the strain of the damaged viscoplastic body; express The first derivative of ; <F ∞ > is the switching function; σ ij represents the total stress; η2 represents the viscosity coefficient of the viscoplastic body; is the deviator of the volumetric strain rate of the viscoplastic body; g ∞ is the long-term yield potential function; σ 11 represents the first principal stress; σ 22 represents the second principal stress; σ 33 represents the third principal stress;

[0142] Specifically, in the embodiment of the present invention, the long-term stability of the high side wall of the station is analyzed to verify the rationality of the development model built, and the data of σ, ε(t) and t are obtained based on the creep test results of the layered weak shale under different bedding angles and different dry-wet cycles. Then, the creep model parameters are identified to obtain the initial parameter values ​​of the model, and the matrix and layered weak plane parameters of the layered rock mass refer to the data in Table 1. The values ​​of some creep parameters are shown in Table 2 below.

[0143] Table 1 Numerical test parameters of slate rock

[0144]

[0145] Table 2 Basic creep parameters of slate with 30° laminar weak plane angle

[0146]

[0147] The creep curve test value of slate at 30° layered weak plane angle is compared with the calculated value. The results are as follows: Figure 4a and Figure 4b As shown in the figure, it can be seen that the model curve is basically consistent with the test curve in the deceleration section, stable section and acceleration section. Although there is a certain deviation, the overall law and trend of the calculated value and the test value are similar and the difference is not large. The simulation results prove the rationality of the creep damage constitutive model developed in this paper.

[0148] In order to further verify the feasibility of the model, the long-term stability of the high side walls of the station was analyzed. For example, the Qingniwaqiao Station is mainly excavated by drilling and blasting. Frequent blasting operations will reduce the quality of the surrounding rock. Therefore, it is necessary to study the excavation stability of the station under the action of blasting damage. Based on the on-site drilling survey and the acoustic wave monitoring data of the station site, the size of the blasting affected area is set as Figure 5 The station calculation model is shown in Figure 6 shown.

[0149] from Figure 7 It can be seen that the horizontal displacement of the side wall increases with the increase in the number of blasting. Without considering the influence of blasting, the maximum horizontal displacement of the side wall is 2.89mm. When the cumulative number of blasting reaches eight times, the maximum horizontal displacement of the side wall reaches 4.94mm, and the displacement increases by 70.93%. It can be seen that the horizontal displacement of the side wall under the influence of blasting has increased significantly. It can be seen that with the increase in the number of blasting, the damage to the surrounding rock caused by blasting gradually increases, causing the station to further move the side wall. Therefore, during the construction process, attention should still be paid to the control of surrounding rock damage.

[0150] During the construction of the high side wall of the station, the blasting construction of the station broke the relative balance of the natural stress of the rock mass, causing secondary cracks in the surrounding rock. Considering the unfavorable factors, the blasting impact area is also set as the dry-wet cycle impact area. The surrounding rock within the blasting area will be affected by the dry-wet cycle of groundwater during the long-term construction process.

[0151] Figure 8 The variation law of the horizontal displacement of the surrounding rock of the station side wall with the number of dry-wet cycles after eight blastings is given. It can be seen from the figure that after the high side wall of the station is formed, the displacement of the side wall changes to a certain extent with the increase of the number of dry-wet cycles in the later period. Taking the maximum horizontal displacement of the side wall as an example, when n'=0, 1, 5, 10, 15 and 20, the maximum displacement values ​​of the side wall are 4.62mm, 5.26mm, 5.62mm, 5.85mm, 6.01mm and 6.03mm respectively. With the increase of the number of dry-wet cycles, the horizontal displacement of the side wall increases further, but the amplitude of its growth rate gradually decreases.

[0152] Considering 8 cycles of blasting and 20 dry-wet cycles, the creep deformation of stations with creep times of 30d, 60d, 90d, 120d, 150d, 180d, and 210d is analyzed. Fig. 9 As shown in the figure, with the increase of creep time, the horizontal displacement of the side wall gradually increases, the initial creep deformation rate is large, and the creep deformation rate gradually decreases in the later period, indicating that the creep time will also aggravate the long-term deformation of the side wall under the action of long-term load.

[0153] Fig.10 The comparison between the long-term monitoring data of the horizontal displacement of the side wall on site and the numerical calculation simulation results of the model in this embodiment is given. It can be seen from the figure that the change trends of the two are basically consistent and the data are relatively close. The comparison can show the accuracy of the model established in this embodiment. At the same time, it can be proved that the support scheme selected by using the calculation results of the model has strong practical significance.

[0154] Fig.11 Schematic diagram of the comparison of calculation results of models using different damage variables. It can be seen from the figure that in the actual numerical simulation process, the calculation results considering blasting, dry-wet cycles and load damage are closer to the on-site monitoring results, and the calculation results without considering the above factors have large errors.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for establishing a high side wall time-dependent deformation model considering bedding surrounding rock damage, characterized in that: The following steps are involved: S1: Obtain the blasting damage variable D used to characterize the degree of weakening of the mechanical properties of the layered rock mass caused by blasting r , the dry-wet cycle damage variable D used to characterize the weakening degree of mechanical properties of layered rock mass caused by dry-wet cycles s and the continuous load damage variable D used to characterize the weakening degree of mechanical properties of layered rock mass caused by load c ; S2: According to the blasting damage variable D r , dry-wet cycle damage variable D s , obtain the first coupled damage variable considering blasting damage and dry-wet cycle damage, and according to the continuous load damage variable D c , get the second coupling damage variable D z ; The second coupled damage variable is a damage variable that comprehensively considers blasting damage, dry-wet cycle damage, and continuous load damage; S3: Based on the second coupled damage variable and the first coupled damage variable, an improved viscoelastic-plastic model considering blasting damage variables and dry-wet cycle damage is established to complete the establishment of a high side wall time-dependent deformation model considering bedding surrounding rock damage; The improved viscoelastic-plastic model is to replace the plastic body in the original viscoelastic-plastic model with the plastic body in the improved ubiquitous joint model; The elastic phase bulk modulus G0, the viscoelastic phase bulk modulus G1, the elastic phase viscosity coefficient η0, and the viscoelastic phase viscosity coefficient η1 in the improved viscoelastic-plastic model are all parameters related to the first coupled damage variable; the viscosity coefficient η2 of the viscoplastic body in the improved viscoelastic-plastic model is related to the second coupled damage variable D z Related parameters.

2. The method for establishing a high side wall time-dependent deformation model considering bedding surrounding rock damage according to claim 1 is characterized in that: The second coupling damage variable D z The acquisition method is as follows: First, consider the blasting damage variable D r and dry-wet cycle damage variable D s The first coupled damage variable under is as follows: D r / s =D r +D s -D r D s Where: D r / s It is the first coupled damage variable considering blasting damage variable and dry-wet cycle damage variable; Then the second coupling damage variable that comprehensively considers the first coupling damage variable and the continuous load damage variable is obtained as: D z =D r / s +D c -D r D c -D c D s +D r D s D c =D r +D s +D c -D r D s -D r D c -D c D s +D r D s D c Where: D r / s is the first coupling damage variable; D r is the blasting damage variable; D s D is the dry-wet cycle damage variable; c is the continuous load damage variable of the layered rock mass during the accelerated creep process; D z is the second coupling damage variable.

3. The method for establishing a high side wall time-dependent deformation model considering bedding surrounding rock damage according to claim 1 is characterized in that: The improved diffuse joint model is established as follows: S31: Based on the elastic theory, the relationship between stress and strain in the plane parallel to the layered anisotropic rock mass and the relationship between stress and strain in the plane perpendicular to the layered anisotropic rock mass are established as follows: Where: ε′ x represents the x-direction strain in the global coordinate system; ε′ y represents the y-direction strain in the global coordinate system; ε′ z represents the z-direction strain in the global coordinate system; σ′ x represents the stress in the x direction in the global coordinate system; σ′ y represents the stress in the y direction in the global coordinate system; σ′ z represents the stress in the z direction in the global coordinate system; γ′ xy represents the shear strain in the xy direction in the global coordinate system; γ′ yz represents the shear strain in the yz direction in the global coordinate system; γ′ xz represents the shear strain in the xz direction in the global coordinate system; τ xy represents the shear stress in the xy direction in the global coordinate system; τ yz represents the shear stress in the yz direction in the global coordinate system; τ xz represents the shear stress in the xz direction in the global coordinate system; E1, μ1, G1 represent the elastic modulus, Poisson's ratio and shear modulus parallel to the layer of the layered anisotropic rock mass, respectively; E2, μ2, G2 represent the elastic modulus, Poisson's ratio and shear modulus normal to the layer of the layered anisotropic rock mass, respectively; S32: The relationship between stress and strain in the plane parallel to the layered anisotropic rock mass and the relationship between stress and strain in the plane perpendicular to the layered anisotropic rock mass are expressed by a matrix as follows: {s'}=[M e ']{e'} Where: [M′ e ] is the elastic matrix of the layered anisotropic medium in the layered normal coordinate system; {σ′} represents the stress in the local coordinate system; {ε′} represents the strain in the local coordinate system; The elastic matrix of the layered anisotropy in the local coordinate system Ox'y'z' is obtained as follows: Where: A3=E1μ2(1+μ1), A1, A2, and A3 are all intermediate calculation parameters; p represents the ratio of the elastic modulus E1 of the plane parallel to the layered anisotropic rock mass to the elastic modulus E2 of the plane normal to the layered anisotropic rock mass; m represents the ratio of the Poisson's ratio μ1 of the plane parallel to the layered anisotropic rock mass to the Poisson's ratio μ2 of the plane normal to the layered anisotropic rock mass; S33: The coordinate transformation matrix [Q] for transforming the global coordinate system into the local coordinate system is expressed as: Where: [Q] represents the coordinate transformation matrix; a1 represents the direction cosines between the x' axis and the x axis; a2 represents the direction cosines between the y' axis and the x axis; a3 represents the direction cosines between the z' axis and the x axis; b1 represents the direction cosines between the x' axis and the y axis; b2 represents the direction cosines between the y' axis and the y axis; b3 represents the direction cosines between the z' axis and the y axis; c1 represents the direction cosines between the x' axis and the z axis; c2 represents the direction cosines between the y' axis and the z axis; c3 represents the direction cosines between the z' axis and the z axis; The direction cosines in the coordinate transformation matrix [Q] are expressed in terms of the azimuth of the rock mass layer as follows; Where: α represents the inclination of the layer; β represents the dip angle of the layer; S35: The stress transformation matrix from the global coordinate system to the local coordinate system is: Where: [L] represents the stress transformation matrix from the global coordinate system to the local coordinate system; Then the conversion relationship between the stress {σ} in the global coordinate system and the stress {σ'} in the local coordinate system is as follows: {σ′}=[L]{σ} The transformation relationship between the strain {ε} in the global coordinate system and the strain {ε'} in the local coordinate system is as follows: {ε′}=[L]{ε} S36: Get the stress in the global coordinate system as: {σ}=[L] T [M' e ][L]{e} Where: [L] T represents the transpose of [L]; Then the elastic matrix in the global coordinate system is: [M e ]=[L] T [M e '][L] Among them, the elastic matrix in the global coordinate system obtained by the stress transformation matrix [L] is expressed as: Where: M 11 、M 16 、M 61 、M 66 are all intermediate calculation parameters, indicating [M e ] in the .

4. The method for establishing a high side wall time-dependent deformation model considering bedding surrounding rock damage according to claim 1 is characterized in that: The improved viscoelastic-plastic model is converted into differential form as follows: Total strain e of creep damage model ij It consists of three parts, and the expression is: Where: e ij is the total strain of the creep damage model; is the strain that damages the elastic element; is the strain that damages the viscoelastic body; is the strain that damages the viscoplastic body; First, for the damaged elastic element, it can be obtained: Where: S ij represents the stress deviator; G0 represents the bulk modulus; D r / s It is the first coupled damage variable considering blasting damage variable and dry-wet cycle damage variable; The above equation can be written as: in: In the formula, represents the updated deviatoric stress tensor; Δt represents the time increment; represents the updated strain deviator; represents the old value of the stress deviator in one time increment; represents the new value of the stress deviator in one time increment; is the old value of the strain deviator; is the new value of the strain deviator; At the same time, for the damaged viscoelastic body, the deviatoric stress of the damaged viscoelastic body is composed of two parts: the spring and the viscoelastic pot, namely: Where: It represents the strain difference of the damaged viscoelastic body; represents the strain that damages the viscoelastic body; So we can get: in, Combining equation (20) and equation (21), we can obtain: Where: represents the strain of the initial damaged viscoelastic body; Δe ij It represents the variation value; Represents the strain difference of the damaged viscoplastic body; represents the strain difference in the viscoelastic stage; represents the old value of the stress deviator in a time increment; A, B, a, b are all intermediate calculation parameters; η1 represents the viscosity coefficient in the viscoelastic stage; G1 represents the bulk modulus in the viscoelastic stage; The characteristic expression of volume is: Where: represents the new value of the viscoelastic body stress; represents the old value of viscoelastic stress; K0 represents the bulk modulus; Δe vol represents the total strain rate; represents the volumetric strain rate of a viscoplastic body; represents the volumetric strain rate of the elastic body; Therefore, the spherical strain of the viscoelastic body is obtained as follows: Where: represents the spherical strain of the damaged viscoelastic body; C and F are both intermediate calculation parameters; K1 represents the bulk modulus of the viscoelastic body; The strain representing the initial strain of the damaged viscoelastic body; Finally, for a viscoplastic body, the viscoplastic strain rate deviator is: Where: g ∞ is the long-term yield potential function; is the deviator of the volumetric strain rate of the viscoplastic body, that is: <F ∞ > is the switch function, which is expressed as follows: In the formula, represents the strain of the damaged viscoplastic body; express The first derivative of ; <F ∞ > is the switching function; σ ij represents the total stress; η2 represents the viscosity coefficient of the viscoplastic body; is the deviator of the volumetric strain rate of the viscoplastic body; g ∞ is the long-term yield potential function; σ 11 represents the first principal stress; σ 22 represents the second principal stress; σ 33 represents the third principal stress.

5. The method for establishing a high side wall time-dependent deformation model considering bedding surrounding rock damage according to claim 2 is characterized in that: The blasting damage variable D r Get as follows: Where, v0 is the acoustic wave velocity of the rock mass before blasting; v is the acoustic wave velocity of the rock mass after blasting; η is the rate of decrease of the speed of sound; D r is the blasting damage variable; The dry-wet cycle damage variable D s Get as follows: Where: D s is the dry-wet cycle damage variable; n is the porosity of the stratified rock mass before the dry-wet cycle; n0 is the porosity after the dry-wet cycle; v s represents the longitudinal wave velocity before the dry-wet cycle; v s ′ represents the longitudinal wave velocity after the dry-wet cycle; a continuous load damage variable of the layered rock mass during accelerated creep; D c =1-e -λt Where: λ is the aging creep parameter; t is time; D c is the continuous load damage variable of the layered rock mass during the accelerated creep process.

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