Constitutive Model for Shear Failure of Structural Plane under True Triaxial Stress-Seepage-Aging Coupling

Abstract

The present invention discloses a constitutive model for shear failure of structural planes under true three-dimensional stress-seepage-pressure-ageing coupling, comprising the following steps: conducting a true three-dimensional stress-seepage-pressure-ageing coupling multi-stage shear test on a rock mass structural plane to obtain the strength and deformation characteristics of the structural plane; based on the test results, determining the calculation method for the true three-dimensional stress loading shear damage D of the rock mass structural plane; determining the evolution functions of the Biot coefficient μ and the permeability coefficient k of the rock mass structural plane; establishing a constitutive model and a numerical method for shear rupture of the structural plane under true three-dimensional stress-seepage-pressure-ageing coupling; and conducting numerical simulation verification of the true three-dimensional stress-seepage-pressure-ageing coupling multi-stage shear test and analyzing the seepage catastrophe of the structural plane tunnel in the water-rich area. The present invention proposes a constitutive model for shear rupture of the structural plane under true three-dimensional stress-seepage-pressure-ageing coupling, which is of great significance for the stability analysis and engineering disaster prediction of the rock mass structural plane project in the water-rich underground area. s Calculation method; determining the evolution functions of the Biot coefficient μ and the permeability coefficient k of the rock mass structural plane; establishing a constitutive model and a numerical method for shear rupture of the structural plane under true three-dimensional stress-seepage-pressure-ageing coupling; and conducting numerical simulation verification of the true three-dimensional stress-seepage-pressure-ageing coupling multi-stage shear test and analyzing the seepage catastrophe of the structural plane tunnel in the water-rich area. The present invention proposes a constitutive model for shear rupture of the structural plane under true three-dimensional stress-seepage-pressure-ageing coupling, which is of great significance for the stability analysis and engineering disaster prediction of the rock mass structural plane project in the water-rich underground area.

Description

Technical Field

[0001] The present invention relates to the field of rock mechanics and rock engineering research, and particularly relates to a method for constructing a constitutive model of shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling. Background Art

[0002] Deep underground engineering is usually in an extremely complex environment, and many safety problems will be encountered during engineering construction, especially the long-term stability problem of rock mass structural planes in the multi-field coupling environment of true three-dimensional stress and osmotic pressure. Scholars at home and abroad have proposed many rock mass constitutive models considering factors such as osmotic pressure and aging for the stability analysis and disaster prediction of underground engineering. However, most of these models are compression models based on stress-seepage pressure coupling, and these models do not consider the changes in Biot coefficient and permeability coefficient during the rock mass rupture process. There are relatively few models suitable for the analysis of shear rupture of structural planes, lacking true three-dimensional stress-seepage pressure-aging coupling structural plane failure criteria and failure deterioration characterization. In addition, the existing structural plane aging models are usually composed of traditional elastic elements, plastic elements and viscous elements, and their characterization functions are relatively simple; there is a lack of fractional-order models considering nonlinear shear aging damage, true three-dimensional stress-seepage pressure-aging coupling effect and accelerated deformation stage.

[0003] In view of the above deficiencies, the present invention proposes a constitutive model of shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling. Considering the coupling effect of true three-dimensional stress loading, Biot coefficient change and aging deterioration on the shear rupture evolution, constructing a constitutive model and numerical method of shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling is of great significance for the stability analysis and engineering disaster prediction of rock mass structural plane projects in underground water-rich areas. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for constructing a constitutive model of shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling, analyze the shear rupture characteristics of rock mass under the action of true three-dimensional stress, osmotic pressure and aging, and provide a more scientific theoretical basis for the excavation design and disaster prevention of rock engineering.

[0005] In order to achieve the above technical objectives, the present invention provides a method for constructing a constitutive model of shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling, and its steps include:

[0006] Step 1: Conduct true three-dimensional shear aging tests under different stress levels and seepage pressures to obtain the strength, deformation and failure characteristics of the rock mass structural plane;

[0007] Step 2: Establish a constitutive model of shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling;

[0008] Step 3: Construct a numerical method for the constitutive model of shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling;

[0009] Step 4: Conduct numerical verification of the constitutive model of shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling and analyze the seepage catastrophe of tunnels with structural planes in water-rich areas.

[0010] In the said Step 1, conduct true three-dimensional shear aging tests under different normal, lateral stresses and seepage pressures to obtain the strength, deformation and failure characteristics of rock mass structural planes;

[0011] In the said Step 2, based on the theories of elastoplastic mechanics, damage mechanics, effective stress principle and three-dimensional strength criterion, construct a constitutive model for shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling. The specific steps are as follows:

[0012] The true three-dimensional stress loading shear damage D of the rock mass structural plane s is expressed as:

[0013]

[0014] where: G0 is the initial shear stiffness of the rock mass structural plane, and G s is the damaged shear stiffness of the rock mass structural plane;

[0015]

[0016] where dτ and dγ are the multi-stage loading shear stress increment and shear strain increment of the rock mass structural plane respectively;

[0017] Calculate the effective stress by the effective stress principle:

[0018]

[0019] where: τ' is the effective shear stress, σ' n is the effective normal stress, and σ' p is the effective lateral stress, and μ and pw are the Biot coefficient and osmotic pressure respectively;

[0020] The Biot coefficient μ of the rock mass structural plane is a function related to the shear damage D s :

[0021] μ = f(D s ) + c s (4)

[0022] where c s is the curve constant;

[0023] Adopt the true three-dimensional stress loading shear damage D of the rock mass structural plane s to describe the evolution of the permeability coefficient k of the rock mass structural plane during the shear failure process:

[0024] k = g(D s ) (5)

[0025] The true three-dimensional stress-seepage-pressure-aging element model consists of four parts: the first part is an elastic element, the second part is a viscoelastic body composed of a parallel connection of an elastic element and a viscous element, the third part is a fractional-order element, and the fourth part is a fractional-order viscoplastic body composed of a parallel connection of a fractional-order element and a plastic element. The four-part model is used in series to describe the viscoelastic-plastic shear mechanical behavior of the rock mass structural plane;

[0026] The constitutive relation of the elastic model in the first part is:

[0027]

[0028] The constitutive relation of the elastic-viscous model in the second part is:

[0029]

[0030]

[0031] The constitutive relation of the fractional-order model in the third part is:

[0032]

[0033]

[0034] The constitutive relation of the fractional-order viscoplastic model in the fourth part is:

[0035]

[0036] Since the four-part model is connected in series, the constitutive relation of the true three-dimensional stress-seepage-pressure-aging model is:

[0037]

[0038]

[0039] Establish the true three-dimensional stress-seepage-pressure-aging coupling shear yield function F of the rock mass in three-dimensional space s :

[0040]

[0041] where: c jp is the cohesion of the structural plane, is the internal friction angle of the structural plane, P, σ ρ are the effective forces, and K is the coefficient related to the effective lateral stress;

[0042] When the effective shear stress τ' is less than the effective crack initiation stress τ' ci , only elastic deformation occurs on the rock mass structural plane; when τ' is greater than or equal to τ' ci , time-dependent deformation occurs on the rock mass structural plane;

[0043]

[0044] When the effective shear stress τ' is greater than the effective damage stress τ' cd , the rock mass structural plane enters the acceleration stage at this time, the deformation rate of the rock mass structural plane gradually increases, and the internal cracks continue to expand and ultimately lead to failure;

[0045]

[0046] In the said step 3, the numerical method of the constitutive model for shear failure of the structural plane under true three-dimensional stress-seepage-pressure-time coupling:

[0047] According to the elastic stress increment formula, we have:

[0048]

[0049] where G s and k n are the shear stiffness and the normal stiffness, and Δγ and Δε n are the shear and normal strain increments;

[0050] The model consists of an elastic body, a viscoelastic body, a fractional-order element, and a fractional-order viscoplastic body. The total strain ε is expressed as:

[0051] ε = ε e + ε ve + ε v + ε vp (18)

[0052] In the formula: ε e , ε ve , ε v , ε vp are the strain matrices of the elastic body, the viscoelastic body, the fractional-order element, and the fractional-order viscoplastic body respectively;

[0053] The stress-strain relationship of the elastic body:

[0054]

[0055]

[0056] where the superscripts N and O represent the updated stress and the stress before update;

[0057] The stress-strain relationship of the viscoelastic body:

[0058]

[0059]

[0060] Stress-strain relationship of fractional-order components:

[0061]

[0062]

[0063] Stress-strain relationship of fractional-order viscoplastic bodies:

[0064]

[0065]

[0066] True three-dimensional stress-seepage pressure-aging coupling shear yield function F of rock mass s and tensile yield function F t :

[0067]

[0068] F t = σ′ t - σ' n (28)

[0069] According to the shear yield function F s , tensile yield function F t and plastic flow rule to determine the shear plastic potential function g s and tensile plastic potential function g t :

[0070]

[0071] g t = σ′ t (30)

[0072] Combining equations (17)-(26), the updated stress is expressed as:

[0073]

[0074]

[0075]

[0076] B = G1G2((t + Δt) α - t α ) (34)

[0077]

[0078] Effective lateral stress vector σ' p Perpendicular to the effective shear stress vector τ' and the effective normal stress vector σ' n , the effective lateral stress vector σ' p is expressed as:

[0079] σ' p = τ' × σ' n (36)

[0080] The effective lateral stress σ' of the element on the structural plane p is the sum of the projection magnitudes of the principal stress vectors σ i '(i = 1, 2, 3) on the element in the direction of the vector σ' p :

[0081]

[0082] In step 4, numerical verification of the constitutive model of shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling and analysis of tunnel seepage catastrophes in water-rich areas of structural planes:

[0083] By numerically simulating the true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test, obtaining strength, deformation and failure results and comparing them with the test results;

[0084] Conducting seepage catastrophe analysis on tunnel projects in water-rich areas, establishing a three-dimensional numerical model of joint structural plane tunnels, applying the constitutive model of shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling to simulate tunnel excavation, and analyzing the mechanical response of the surrounding rock of the structural plane under true three-dimensional stress-seepage-pressure-aging coupling.

[0085] The beneficial effects of the present invention are:

[0086] 1. The present invention establishes a constitutive model of shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling and a numerical method, which can be used to simulate and analyze the changes in the mechanical properties of deep-buried rock masses under the coupling action of true three-dimensional stress, osmotic pressure and aging.

[0087] 2. After secondary development programming of the model established by the present invention, it can be applied to the excavation design and disaster prevention of underground rock mass projects in water-rich areas. Description of the Drawings

[0088] Figure 1 is the construction flow chart of the constitutive model of shear failure of structural planes under true three-dimensional stress-seepage-pressure-aging coupling of the present invention;

[0089] Figure 2 is the stress path of the true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test;

[0090] Figure 3 Shear strain-time curve of the true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test;

[0091] Figure 4 Evolution of Biot coefficient μ of rock mass under true three-dimensional stress-seepage-pressure-aging coupling;

[0092] Figure 5 Evolution of permeability coefficient k of rock mass under true three-dimensional stress-seepage-pressure-aging coupling;

[0093] Figure 6 True three-dimensional stress-seepage-pressure-aging element model;

[0094] Figure 7 Shear strain-time curve and simulation results of the true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test;

[0095] Figure 8 Surrounding rock plastic zone after tunnel excavation of structural plane under true three-dimensional stress-seepage-pressure-aging coupling;

[0096] Figure 9 Surrounding rock pore pressure nephogram after tunnel excavation of structural plane under true three-dimensional stress-seepage-pressure-aging coupling. Specific implementation manner

[0097] The following describes the specific implementation manner of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the specific implementation manner. It should be noted here that any creation based on the present invention or creation attached to the present invention is within the protection scope of the present invention.

[0098] This embodiment provides a constitutive model for shear failure of structural plane under true three-dimensional stress-seepage-pressure-aging coupling, using limestone as the rock mass specimen and conducting engineering applications to verify the rationality and reliability of the model.

[0099] Refer to Figure 1 , Figure 1 shows the construction flow chart of the constitutive model for shear failure of structural plane under true three-dimensional stress-seepage-pressure-aging coupling, and the method includes Step 1 and Step 4;

[0100] In Step 1, a true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test is carried out on the limestone specimen to obtain the aging deformation result of the limestone. The stress path of the true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test is as Figure 2 shown; Figure 3 shows the shear strain-time curve of the true three-dimensional stress-seepage-pressure-aging coupling multi-stage shear test;

[0101] In Step 2, based on the theories of elastoplastic mechanics, damage mechanics, effective stress principle, and three-dimensional strength criterion, a constitutive model for shear failure of structural planes under true three-dimensional stress-seepage pressure-aging coupling is constructed. The specific steps are as follows:

[0102] The true three-dimensional stress loading shear damage D of the rock mass structural plane s is expressed as:

[0103]

[0104] where: G0 is 10.9 GPa, and G s is the damage shear stiffness of the rock mass structural plane;

[0105]

[0106] where dτ and dγ are the multi-stage loading shear stress increment and shear strain increment of the rock mass structural plane;

[0107] The effective stress is calculated by the effective stress principle:

[0108]

[0109] where: τ' is the effective shear stress, σ' n is the effective normal stress, σ' p is the effective lateral stress, and μ and p w are the Biot coefficient and the osmotic pressure, respectively;

[0110] The Biot coefficient μ of the rock mass structural plane is a function related to the shear damage D s as follows:

[0111]

[0112] The normal stress σ n = 15 MPa, σ p = 10 MPa, and p w = 1 MPa, the evolution of the Biot coefficient μ under true three-dimensional stress-seepage pressure-aging coupling is as Figure 4 shown;

[0113] After the rock mass is subjected to engineering disturbances such as excavation unloading, the generation and expansion of its fissures will lead to an increase in the permeability coefficient, which gradually increases with damage accumulation until it stabilizes after the dominant fissures penetrate. Therefore, the permeability coefficient k of the rock mass structural plane can be described by D s as follows:

[0114]

[0115] The normal stress σ n = 15 MPa, σ p = 10 MPa, and p wThe evolution of the permeability coefficient k under a true three-dimensional stress-seepage pressure-aging coupling at 1 MPa is as follows Figure 5 shown;

[0116] The true three-dimensional stress-seepage pressure-aging element model consists of four parts: the first part is an elastic element, the second part is a viscoelastic body composed of a parallel connection of an elastic element and a viscous element, the third part is a fractional-order element, and the fourth part is a fractional-order viscoplastic body composed of a parallel connection of a fractional-order element and a plastic element. The four-part model is used in series to describe the viscoelastic-plastic shear mechanical behavior of the rock mass structural plane, as shown in Figure 6 shown;

[0117] The constitutive relationship of the elastic model in the first part is:

[0118]

[0119] The constitutive relationship of the elastic-viscous model in the second part is:

[0120]

[0121]

[0122] The constitutive relationship of the fractional-order model in the third part is:

[0123]

[0124]

[0125] The constitutive relationship of the fractional-order viscoplastic model in the fourth part is:

[0126]

[0127] Establish the true three-dimensional stress-seepage pressure-aging coupling shear yield function F of the rock mass in three-dimensional space:

[0128]

[0129] When the effective shear stress τ' is less than the effective initial cracking stress τ' ci = 8 MPa, only elastic deformation occurs on the rock mass structural plane; when the effective shear stress τ' is greater than or equal to τ' ci , time-dependent deformation occurs on the rock mass structural plane;

[0130]

[0131] When the effective shear stress τ' is greater than or equal to the effective damage stress τ' cd = 17 MPa, the rock mass structural plane enters the acceleration stage at this time;

[0132]

[0133] Since the four - part model is connected in series, the constitutive relation of the aging model is as follows:

[0134]

[0135]

[0136] In step 3, the numerical method of the constitutive model for shear failure of structural planes under true three - dimensional stress - seepage - aging coupling:

[0137] According to the elastic stress increment formula, we have:

[0138]

[0139] where G s and k n are the shear stiffness and normal stiffness, and Δγ and Δε n are the shear and normal strain increments;

[0140] The model consists of an elastic body, a visco - elastic body, a fractional - order element, and a fractional - order visco - plastic body. The total strain ε is expressed as:

[0141] ε = ε e + ε ve + ε v + ε vp

[0142] In the formula: ε e , ε ve , ε v , ε vp are the strain matrices of the elastic body, the visco - elastic body, the fractional - order element, and the fractional - order visco - plastic body, respectively;

[0143] The stress - strain relationship of the elastic body:

[0144]

[0145]

[0146] where the superscripts N and O represent the updated stress and the stress before update;

[0147] The stress - strain relationship of the visco - elastic body:

[0148]

[0149]

[0150] The stress - strain relationship of the fractional - order element:

[0151]

[0152]

[0153] Stress-strain relationship of fractional-order viscoplastic body:

[0154]

[0155]

[0156] True three-dimensional stress-seepage pressure-aging coupling shear yield function F of rock mass s and tensile yield function F t :

[0157]

[0158] F t = σ t '- σ' n

[0159] According to the shear yield function F s , tensile yield function F t and plastic flow rule to determine the shear plastic potential function g s and tensile plastic potential function g t :

[0160]

[0161] g t = σ t '

[0162] Combining the above equations, the updated stress is expressed as:

[0163]

[0164]

[0165]

[0166] B = G1G2((t + Δt) α - t α )

[0167]

[0168] Effective lateral stress vector σ' p is perpendicular to the effective shear stress vector τ' and the effective normal stress vector σ' n :

[0169] σ' p = τ'×σ' n

[0170] The effective lateral stress σ' of the element on the structural plane p The magnitude is the principal stress vector σ on the element i '(i = 1, 2, 3) projected on the direction of the vector σ' p The sum of the projected magnitudes:

[0171]

[0172] In step 4, through numerical simulation and engineering application analysis of the true three-dimensional stress-seepage-pressure-ageing coupling multi-stage shear test, verify the constitutive model of shear failure of the structural plane under true three-dimensional stress-seepage-pressure-ageing coupling:

[0173] Conduct numerical simulation on the true three-dimensional stress-seepage-pressure-ageing coupling multi-stage shear test, Figure 7 Show the shear strain-time curve and simulation results of the true three-dimensional stress-seepage-pressure-ageing coupling multi-stage shear test;

[0174] Establish a three-dimensional tunnel numerical model of the joint structural plane. The size of the tunnel model is 60m×60m×30m, and the tunnel radius is 3.6m; two joints with an inclination angle of 60° are set at the crown of the tunnel model, and the tunnel grid elements are locally refined;

[0175] Table 1, Table 2 and Table 3 list the initial in-situ stress, mechanical parameters and model parameters respectively. The permeability coefficient is 1e-7m / s, and the initial pore water pressure is 1.2MPa;

[0176] Figure 8 and Figure 9 Are the plastic zone and pore pressure nephograms of the surrounding rock after tunnel excavation of the structural plane under true three-dimensional stress-seepage-pressure-ageing coupling.

[0177] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

[0178] Table 1 Initial in-situ stress of the surrounding rock

[0179]

[0180] Table 2 Mechanical parameters

[0181]

[0182] Table 3 Model parameters

[0183]

Claims

1. Establish a true three-dimensional stress-seepage-time coupling structural surface shear failure constitutive model, including the following steps: S1. Carry out true three-dimensional stress-seepage pressure-time-dependent coupled multi-stage shear tests on the rock mass structure surface at different stress levels and seepage pressures to obtain strength and deformation characteristics; S2. Determine the shear damage D of the rock mass structure surface under true three-dimensional stress s ; S3. Calculate the effective shear stress τ' and effective normal stress σ' by the effective stress principle n , effective lateral stress σ' p ; S4. Determine the Biot coefficient μ and permeability coefficient K of the rock mass structural surface and the shear damage D s The relationship function of Biot coefficient μ of rock mass structural surface and shear damage D s The relationship function: Where: a s , b s and c s is the Biot coefficient curve constant; The true three-dimensional stress loading shear damage D of the rock mass structural surface is used. s To describe the evolution of the permeability coefficient K of the rock mass structural surface during shear failure: Where: a k , b k and c k is the permeability curve constant; S5. Establish a true three-dimensional stress-permeability-time-dependent element model, which consists of four parts: the first part is the elastic element, the second part is an elastic-viscous body composed of elastic elements and viscous elements in parallel, the third part is a fractional-order element, and the fourth part is a fractional-order viscoplastic body composed of fractional-order elements and plastic elements in parallel. The four-part model is used in series to describe the viscoelastic-plastic shear mechanical behavior of the rock mass structural surface; The constitutive relation of the elastic model in the first part is: The constitutive relation of the viscoelastic model in the second part is: The constitutive relation of the fractional-order model in the third part is: The constitutive relation of the fractional-order viscoplastic model in the fourth part is: Since the four-part model is connected in series, the constitutive relation of the time-dependent model is: τ′=τ′1=τ′2=τ′3=τ′4 γ=γ1+γ2+γ3+γ4 Establish the true three-dimensional stress-permeability-time-dependent coupled shear yield function F of rock mass in three-dimensional space: Among them, c jp is the cohesion of the structural surface, is the internal friction angle of the structural surface, P, σ ρ is the effect strength, K p is the effective lateral stress coefficient; When the effective shear stress τ' is less than the effective crack initiation stress τ' ci When the effective shear stress τ' is greater than or equal to τ', the rock mass structural surface only undergoes elastic deformation; ci When , the rock mass structural surface undergoes time-dependent deformation; When the effective shear stress τ' is greater than or equal to the effective damage stress τ' cd At this time, the rock mass structural surface enters the acceleration stage, the deformation rate of the rock mass structural surface gradually increases, and its internal cracks continue to expand and eventually lead to destruction; S6. A numerical method for constructing a true three-dimensional stress-permeability-time-dependent coupled shear failure constitutive model of the structural surface; S7. Numerical verification of the shear failure constitutive model of structural surface under true three-dimensional stress-seepage pressure-time coupling and analysis of seepage disaster of structural surface tunnel in water-rich area.

2. The true three-dimensional stress-osmotic pressure-time-dependent coupled structural surface shear failure constitutive model according to claim 1 is characterized in that: In step S2, the true three-dimensional stress loading shear damage D of the rock mass structural surface is determined. s : Where: G0 is the initial shear stiffness of the rock mass structural surface, G s is the damage shear stiffness of the rock mass structural surface; Where: dτ and dγ are the shear stress increment and shear strain increment of the rock mass structural surface under multi-level loading.

3. The true three-dimensional stress-osmotic pressure-time-dependent coupled structural surface shear failure constitutive model according to claim 1 is characterized in that: In step S3, the effective stress is calculated according to the effective stress principle: Where τ' is the effective shear stress, σ' n is the effective normal stress, σ' p is the effective lateral stress, μ and p w are the Biot coefficient and osmotic pressure, respectively.

4. The true three-dimensional stress-osmotic pressure-time-dependent coupled structural surface shear failure constitutive model according to claim 1 is characterized in that: In the step S6, a numerical method for constructing a shear failure constitutive model of a structural surface under true three-dimensional stress-seepage-time coupling is implemented; According to the elastic stress increment formula: Δτ'=G s Dg Ds' n =k n No n Among them, G s and k n are the shear stiffness and normal stiffness, Δγ and Δε n are the shear and normal strain increments; The model consists of elastic bodies, viscoelastic bodies, fractional-order elements and fractional-order viscoplastic bodies. The total strain ε is expressed as: e=e e +e ve +e v +e vp Where: ε e , ε ve , ε v , ε vp are the strain matrices of elastic body, viscoelastic body, fractional element and fractional viscoplastic body respectively; Stress-strain relationship of elastic body: Among them, the superscripts N and O represent the stress after and before the update; Stress-strain relationship of viscoelastic body: Stress-strain relationship of fractional-order elements: The stress-strain relationship of fractional viscoplastic body: True three-dimensional stress-seepage-pressure-time coupled shear yield function F of rock mass s and the tensile yield function F t : F t =σ′ t -s′ n According to the shear yield function F s , tensile yield function F t and plastic flow law to determine the shear plastic potential function g s and the tensile plastic potential function g t : g t =σ′ t The updated stress is expressed as: B=G1G2((t+Δt) α -t α ) Effective lateral stress vector Perpendicular to the effective shear stress vector and the effective normal stress vector but: The effective lateral stress σ' of the unit on the structural surface p The magnitude is the principal stress vector on the element In vector The sum of the projection sizes in the direction of :

5. The true three-dimensional stress-osmotic pressure-time-dependent coupled structural surface shear failure constitutive model according to claim 1 is characterized in that: In the step S7, the numerical verification of the structural surface shear failure constitutive model under true three-dimensional stress-seepage pressure-time coupling and the seepage disaster analysis of the structural surface tunnel in the water-rich area are carried out; By numerically simulating true three-dimensional stress-seepage pressure-time-effect coupled multi-stage shear tests at different stress levels and seepage pressures, the deformation and failure results are obtained and compared with the test results. A three-dimensional tunnel numerical model of joint structural surfaces is established, and the tunnel excavation simulation is carried out using the shear failure constitutive model of the structural surface under true three-dimensional stress-seepage pressure-time-effect coupling, and the seepage disaster analysis of tunnel projects in water-rich areas is carried out.

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