Rock mass structural surface three-dimensional failure criterion considering lateral stress effect and construction method

Abstract

The invention discloses a rock mass structural surface three-dimensional failure criterion considering a lateral stress effect and a construction method thereof. The construction process comprises the following steps: S1, carrying out a true triaxial shear test to determine peak strength of a rock mass structural surface under the combination of different normal stress sigma n and different lateral stress sigma p; s2, obtaining a shear peak strength change rule under the action of different normal stresses sigma n under true triaxial, and constructing a shear peak strength function F1 (sigma n) of the rock mass structural plane; s3, obtaining a shear peak strength change rule under the action of different lateral stresses sigma p under true triaxial, and constructing a shear peak strength function F2 (sigma p) of the rock mass structural plane; s4, constructing a shear peak intensity function F3 (sigma n, sigma p) in a three-dimensional stress state, and determining an envelope surface form of the shear peak intensity function; and S5, carrying out true triaxial shear tests on the rock mass structural surfaces with different lithology, verifying and perfecting a shear peak strength function F (sigma n, sigma p) in a three-dimensional stress state, and constructing a rock mass structural surface three-dimensional failure criterion considering the lateral stress effect.

Description

Technical Field

[0001] The invention relates to the field of rock mechanical properties and engineering research, and in particular to a three-dimensional failure criterion of a rock mass structural surface considering lateral stress effects and a construction method thereof. Background Art

[0002] Layered rock mass is a typical geological body widely distributed in rock engineering, which plays a key role in the disaster type and surrounding rock stability of rock engineering after excavation. In tunnel engineering, especially under deep burial conditions, the layered rock mass of the surrounding rock is in a true three-dimensional ground stress state. After excavation and unloading, the spandrel part of the tunnel surrounding rock is prone to shear failure.

[0003] At present, most scholars' research shows that structural surfaces have a significant impact on the mechanical behavior of rocks. However, most of the studies are about the mechanical behavior of layered rocks as a whole (combination of layers and matrix), not the mechanical behavior of rock bedding planes. In particular, the mechanical behavior of the layers of layered rocks under true three-dimensional stress has not been studied, and the Mohr-Coulomb criterion does not take lateral stress into account, and cannot be accurately used as a criterion for shear failure of rocks under true triaxial conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a three-dimensional failure criterion of rock structure surface considering the lateral stress effect and its construction method, to predict the shear mechanical properties and failure behavior of rock structure surface under true three-dimensional stress level, and to provide a theoretical basis for the prediction of shear failure disasters in high-stress deep engineering.

[0005] In order to achieve the above technical objectives, the present invention provides a three-dimensional failure criterion of a rock mass structural surface considering the lateral stress effect and a construction method thereof, which comprises:

[0006] S1. Conduct true triaxial perturbation shear tests to determine different normal stresses σ n and different lateral stresses σ p The peak strength of the rock mass structural surface under the combination; S2, obtain the same lateral stress σ under true triaxial p , different normal stress σ n The shear peak strength variation law under the action of the rock mass structure surface is constructed, and the shear peak strength function F1(σ n );

[0007] S3. Obtain the same normal stress σ under true triaxial n , different lateral stress σ p The shear peak strength variation law under the action of the rock mass structure surface is constructed, and the shear peak strength function F2(σ p );

[0008] S4, based on steps S2 and S3, construct the shear peak strength function F3 (σ p, σ n ), determine the envelope morphology of the shear peak intensity function;

[0009] S5. Conduct true triaxial shear tests on rock mass structural surfaces of different lithology and rock mass structural surface types to verify and improve the shear peak strength function under three-dimensional stress state, determine the reasonable range of model parameters and the influence of model parameters on the envelope of shear peak strength function, and construct a three-dimensional failure criterion F(σ n , σ p ).

[0010] In step S1, shear tests under the same lateral stress and different normal stresses, and under the same normal stress and different lateral stresses are carried out to determine the different normal stresses σ n and different lateral stresses σ p Peak strength of rock mass structural plane under the combination;

[0011] In step S2, the variation law of the shear peak strength under the same lateral stress and different normal stresses under true triaxial conditions is obtained, and the shear peak strength function F1 (σ n ) is:

[0012] A1. Based on the peak strength of the rock mass structural surface obtained in step S1, the variation law of the rock shear peak strength under the same lateral stress and different normal stress conditions in a three-dimensional stress state is constructed;

[0013] A2. Construct the shear peak strength function F1(σ n ):

[0014] Where a is a stress parameter related to cohesion and lateral stress, is the angle of internal friction.

[0015] In step S3, the same normal stress σ under true triaxial pressure is obtained. n , different lateral stress σ p The shear peak strength variation law under the action of the rock mass structure surface is constructed, and the shear peak strength function F2(σ p ) is:

[0016] B1. Based on the peak strength of the rock mass structural surface obtained in step S1, the variation law of the rock shear peak strength under the same lateral stress and different normal stress conditions in a three-dimensional stress state is constructed;

[0017] B2. Construct the shear peak strength function F2(σ p ):

[0018] Where b is the stress parameter related to cohesion and normal stress, c is the lateral stress effect, and σ ρ is the lateral stress corresponding to the maximum shear stress of the layered rock, and K is the equivalent lateral stress with the same strength as when the lateral stress is 0.

[0019] In step S4, the rock mass structural surface failure function F3 (σ n , σ p ), the method for determining the envelope morphology of the shear peak intensity function is:

[0020] C1. Based on the shear peak strength law of rock under the same lateral stress condition and different normal conditions, and under the same normal stress condition and different lateral stress conditions, the three-dimensional failure law of rock structure surface under three-dimensional stress state is obtained;

[0021] C2. Construct the rock mass structural surface failure function F3 (σ p , σ n ):

[0022] Where d is a stress parameter related to cohesion and other factors;

[0023] In step S5, true triaxial shear tests are carried out on rock mass structural surfaces of different lithologies to verify and improve the shear peak strength function F(σ n , σ p ), determine the range of values ​​of the three-dimensional failure model parameters of different lithologies and the influence of the model parameters on the envelope of the shear peak strength function, and construct the three-dimensional failure criterion of the rock mass structural surface considering the lateral stress effect as follows:

[0024] D1. Conduct true triaxial shear tests on rock mass structural surfaces of different lithologies to obtain the shear peak strength of rock masses of different lithologies;

[0025] D2. Substitute the shear peak strength of the rock mass structure surface of different lithologies into the shear peak strength function of the rock mass structure surface under three-dimensional stress F3 (σ n , σ p ), to obtain the range of model parameter values ​​for rock mass structural surfaces of different lithologies;

[0026] D3. Single changes are made to the obtained rock mass structural surface model parameters of different lithologies to determine the influence of the model parameters on the envelope of the shear peak strength function, thereby constructing the three-dimensional failure criterion F(σ n , σ p ):

[0027] in, is the internal friction angle, P is the lateral stress effect, σ ρ is the lateral stress corresponding to the maximum shear stress on the rock mass structural surface, K is the lateral stress with the same shear peak strength when the lateral stress is 0, and D is a stress parameter related to cohesion and other factors.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention constructs a shear peak strength function that takes into account the effect of lateral stress through a true triaxial shear test. The physical meaning of the parameters is clear and can be used as a criterion for the shear failure of rocks caused by the cyclic operation of tunnel excavation construction.

[0030] 2. Based on the shear failure morphology of rock structural surfaces under three-dimensional stress state, the present invention constructs a three-dimensional failure criterion of rock structural surfaces under the combined action of normal stress and lateral stress, and fully characterizes the peak strength law of rock under shear action under three-dimensional stress.

[0031] 3. After secondary development, the three-dimensional failure criterion of rock mass structural surface considering lateral stress effect constructed by the present invention can be used as a criterion for shear failure of surrounding rock mass in underground rock engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of the construction of the three-dimensional failure criterion of the rock mass structural surface considering the lateral stress effect and the construction method thereof according to the present invention;

[0033] Figure 2 The stress-deformation law of granite under the same normal stress and different lateral stress conditions;

[0034] Figure 3 The stress-deformation law of granite under the same lateral stress and different normal stress conditions;

[0035] Figure 4 The variation law of peak strength of granite with normal stress under the same lateral stress and different normal stress conditions;

[0036] Figure 5 The peak strength of granite varies with lateral stress under the same normal stress and different lateral stress conditions;

[0037] Figure 6 The three-dimensional failure criterion and envelope surface of granite structure surface considering the lateral stress effect;

[0038] Figure 7 The influence of the three-dimensional failure criterion model parameter P of the granite structural surface on the envelope surface morphology;

[0039] Figure 8 is the parameter σ of the three-dimensional failure criterion model of granite structural surface ρ Impact on the envelope morphology;

[0040] Fig. 9 The influence of the parameter K of the three-dimensional failure criterion model of granite structural surface on the envelope surface morphology;

[0041] Fig.10 The three-dimensional failure criterion and envelope surface of limestone structure considering the lateral stress effect;

[0042] Fig.11 The three-dimensional failure criterion and envelope surface of the limestone structural surface considering the lateral stress effect. DETAILED DESCRIPTION

[0043] The specific implementation of the present invention is described below in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the specific implementation. It should be noted that all creations based on or dependent on the present invention are within the protection scope of the present invention.

[0044] Embodiment 1:

[0045] This embodiment provides a method for constructing and verifying the accuracy and rationality of a three-dimensional failure criterion of a rock structure surface taking into account the lateral stress effect and a construction method thereof using granite as a rock sample.

[0046] refer to Figure 1 , Figure 1 A flowchart of the construction of a three-dimensional failure criterion of a rock mass structural surface considering the lateral stress effect and a construction method thereof is shown, the method comprising steps S1 to S5:

[0047] In step S1, a true triaxial shear test is performed to determine the different normal stresses σ n and different lateral stresses σ p The peak strength of the structural surface of granite under the combination is shown in Table 1; and the stress-displacement curves under different normal stress and different lateral stress conditions are obtained, as shown in Table 1. Figure 2 and 3 shown.

[0048] In step S2, the same lateral stress σ under true triaxial pressure is obtained p , different normal stress σ n The variation law of shear peak strength under the action of Figure 4 As shown, the corresponding parameters a=26.33MPa, and the peak shear strength function F1(σ n ): F1(σ n )=σn tan(59.57°)+26.33

[0049] In step S3, the normal stress σ under true triaxial pressure is obtained. n , different lateral stress σ p The variation law of shear peak strength under the action of Figure 5 As shown, the corresponding parameters b = 29.87MPa, c = 5.24MPa, σ ρ =23.15MPa, K = 29.87MPa, and the peak shear strength function F2 (σ p ):

[0050] In step S4, based on the corresponding parameters obtained in steps S2 and S3 under the three-dimensional stress state, the rock mass structural surface failure function F3 (σ p , σ n ),in, c=5.24MPa、σ ρ =23.15MPa, K=29MPa, d=22.84MPa:

[0051] In step S5, a true triaxial shear test is performed on the granite to verify and improve the shear peak strength function F(σ n , σ p ) The three-dimensional failure criterion of granite structural surface considering the lateral stress effect and the envelope surface such as Figure 6 As shown; verify and improve the shear peak strength function, determine the value range of the three-dimensional failure model parameters of different lithologies and the influence of the model parameters on the envelope of the shear peak strength function, such as Figure 7 , 8 , as shown in Figure 9. Table 1 Peak shear strength of granite structure surface under three-dimensional stress state

[0052] Embodiment 2:

[0053] This embodiment provides a method for constructing and verifying the accuracy and rationality of a three-dimensional failure criterion of a rock structure surface taking into account the lateral stress effect and a construction method thereof using limestone as a rock sample.

[0054] refer to Figure 1 , Figure 1 A flowchart of the construction of a three-dimensional failure criterion of a rock mass structural surface considering the lateral stress effect and a construction method thereof is shown, the method comprising steps S1 to S5:

[0055] In step S1, a true triaxial shear test is performed to determine the different normal stresses σ n and different lateral stresses σ p The peak strength of the structural surface of limestone under the combination is shown in Table 1; and the stress-displacement curves under different normal stress and different lateral stress conditions are obtained.

[0056] In step S2, the same lateral stress σ under true triaxial pressure is obtained p , different normal stress σ n The variation law of shear peak strength under the action of a=13.77MPa, and the peak shear strength function F1(σ n ): F1(σ n )=σ n tan(56.7°)+13.77

[0057] In step S3, the normal stress σ under true triaxial pressure is obtained. n , different lateral stress σ p The shear peak strength variation law under the action of the load is obtained, and the corresponding parameters are b = 12.63MPa, c = 10.92MPa, σ ρ =3.5MPa, K = 2.73MPa, and the peak shear strength function F2 (σ p ):

[0058]

[0059] In step S4, based on the corresponding parameters obtained in steps S2 and S3 under the three-dimensional stress state, the limestone structural surface failure function F3 (σ p , σ n ),in c=10.92MPa、σ ρ =3.5MPa, K = 2.73MPa, d = 12.63MPa, determine the shear peak strength function F3 (σ p , σ n ):

[0060]

[0061] In step S5, a true triaxial shear test is performed on the limestone to verify and improve the shear peak strength function F(σ n , σ p ), the three-dimensional failure criterion of limestone structural surface considering the lateral stress effect and the envelope surface such as Fig.10 shown. Table 2 Peak shear strength of limestone structural surface under three-dimensional stress state

[0062] Embodiment 3:

[0063] This embodiment provides a method for constructing and verifying the accuracy and rationality of a three-dimensional failure criterion of a rock structure surface taking into account the lateral stress effect and a construction method thereof using slate as a rock sample.

[0064] refer to Figure 1 , Figure 1 A flowchart of the construction of a three-dimensional failure criterion of a rock mass structural surface considering the lateral stress effect and a construction method thereof is shown, the method comprising steps S1 to S5:

[0065] In step S1, a true triaxial shear test is performed to determine the different normal stresses σ n and different lateral stresses σ p The peak strength of the structural surface of the slate under the combination is shown in Table 3; and the stress-displacement curves under different normal stress and different lateral stress conditions are obtained.

[0066] In step S2, the same lateral stress σ under true triaxial pressure is obtained p , different normal stress σ n The variation law of shear peak strength under the action of a=6.97MPa, and the peak shear strength function F1(σ n ): F1(σ n )=σ n tan(34.7°)+6.97

[0067] In step S3, the normal stress σ under true triaxial pressure is obtained. n , different lateral stress σ p The shear peak strength variation law under the action of the load is obtained, and the corresponding parameters are b = 10.70MPa, c = 14.58MPa, σ ρ =7.00MPa, K = 1.79MPa, and the peak shear strength function F2 (σ p ):

[0068]

[0069] In step S4, based on the corresponding parameters obtained in steps S2 and S3 under the three-dimensional stress state, the slate structural surface failure function F3 (σ p , σ n ),in c=14.583MPa、σ ρ =7.0MPa, K = 1.79MPa, d = 6.20MPa, determine the shear peak strength function F3 (σ p , σ n ):

[0070]

[0071] In step S5, a true triaxial shear test is performed on the slate to verify and improve the shear peak strength function F(σ n ,σ p ), the three-dimensional failure criterion of slate structure surface considering lateral stress effect and the envelope surface such as Fig.11 shown. Table 3 Structural surface shear peak strength of slate under three-dimensional stress state

[0072] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. The three-dimensional failure criterion of rock mass structural surface considering lateral stress effect and its construction method include the following steps: S1. Conduct true triaxial shear tests to determine different normal stresses σ n and different lateral stresses σ p Peak strength of rock mass structural plane under the combination; S2. Obtain the same lateral stress σ under true triaxial p , different normal stress σ n The shear peak strength variation law under the action of the rock mass structure surface is constructed, and the shear peak strength function F1(σ n ), construct the shear failure function F1(σ n ) is: A1. Based on the shear peak strength obtained in step S1 and the Mohr-Coulomb criterion, the shear peak strength law of the rock mass structural surface under the same lateral stress and different normal stress conditions in the three-dimensional stress state is established; A2. Construct the shear peak strength function F1(σ n ): Where a is a stress parameter related to cohesion and lateral stress, is the internal friction angle; S3. Obtain the same normal stress σ under true triaxial n , different lateral stress σ p The shear peak strength variation law under the action of the rock mass structure surface is constructed, and the shear peak strength function F2(σ p ), construct the shear failure function F2(σ p ) is: B1. Based on the shear peak strength obtained in step S1, the shear peak strength law of the rock mass structural surface under the same normal stress and different lateral stress conditions in the three-dimensional stress state is constructed; B2. Construct the shear peak strength function F2(σ p ): Where b is the stress parameter related to cohesion and normal stress, c is the lateral stress effect, and σ ρ is the lateral stress corresponding to the maximum shear stress on the structural surface of the rock mass, and K is the lateral stress with the same strength as the peak shear strength when the lateral stress is 0; S4, based on steps S2 and S3, construct the shear peak strength function F3 (σ n， σ p ), determine the envelope morphology of the shear peak strength function, and construct the shear peak strength function F3 (σ p， σ n ) is: C1. The shear peak strength law of rock mass structural surface under the conditions of the same normal stress and different lateral stresses and the same lateral stress and different normal stresses in three-dimensional stress state, and the shear peak strength law of rock mass structural surface under three-dimensional stress state are constructed; C2. Construct the shear peak strength function F3(σ n， σ p ): Where d is a stress parameter related to cohesion and other factors; S5. Conduct true triaxial shear tests on rock mass structural surfaces of different lithology and rock mass structural surface types to verify and improve the shear peak strength function F(σ n， σ p ), determine the reasonable range of model parameters and the influence of model parameters on the envelope of shear peak strength function, and construct a three-dimensional failure criterion for rock mass structural surface considering the lateral stress effect.

2. The three-dimensional failure criterion of rock mass structural surface considering lateral stress effect and its construction method as claimed in claim 1 are characterized in that: In the step S1, true triaxial shear tests are carried out on the rock mass structural surface under different normal stresses and the same lateral stress conditions and under different lateral stresses and the same normal stress conditions to obtain corresponding peak strengths.

3. The three-dimensional failure criterion of rock mass structural surface considering lateral stress effect and its construction method as claimed in claim 1 are characterized in that: In step S5, true triaxial shear tests are carried out on rock mass structural surfaces of different lithologies to verify and improve the rock mass structural surface failure function F(σ n , σ p ), determine the range of three-dimensional failure model parameters for different lithologies and the influence of model parameters on the envelope of shear peak strength function, and construct a three-dimensional failure criterion for rock mass structural surfaces considering the lateral stress effect.

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