A method for calculating the shear strength of the structural surface under the anchoring of shear-type anchor rods

Abstract

The present invention provides a method for calculating the shear strength of a structural surface anchored by a shear-type anchor, comprising the following steps: obtaining the initial shear force, installation angle, diameter, length of the bending section, and elastic modulus of the shear-type anchor; obtaining the compressive strength, normal stress, internal friction angle, cohesion, and reaction coefficient of the rock structure surface; calculating the rotation angle at the deformation point of the shear-type anchor; calculating the axial component of the force on the shear-type anchor; calculating the yield strength of the shear-type anchor, determining whether the anchor has yielded, calculating the shear force and the axial component of the force on the anchor when yielding, and calculating the shear strength of the structural surface anchored by the shear-type anchor. The present invention starts from the bedding rock slope anchored by the shear-type anchor, uses the initial shear force as the starting force, and can quantitatively calculate the shear strength of the structural surface under the shear-type anchor anchoring condition, and can accurately evaluate the anchoring effect of the shear-type anchor.

Description

Technical Field

[0001] The present invention relates to the technical field of geological disaster protection and reinforcement, and in particular to a method for calculating the shear strength of a structural surface anchored by a shear-type anchor rod. Background Art

[0002] In recent years, the frequent occurrence of slope disasters has seriously affected the safety of people's lives and activities. Exploring slope disaster prevention and control technologies has become an urgent problem to be solved. Among the cases of slope instability, the most common disaster is the instability of bedding rock slopes. After exploring the stability of the slope, the traditional reinforcement method is to strengthen the mechanical properties of the slope by setting prestressed anchor cables, prestressed anchor rods, anchor rods, anti-slip piles, etc. in the slope. However, the disadvantage of ordinary anchor rods is that when the rod body is subjected to shearing, it is prone to shear failure, and its service life is short, which can easily cause slope anchor failure.

[0003] As a new type of anchor, the shear bolt has an additional free section compared to conventional anchor bolts. Its design allows for inter-layer shifting, which helps the shear strength of the rock layers contribute to slope stability. Compared to conventional anchor bolts, the shear bolt is more effective at securing the slope and offers greater durability. However, the shear bolt is still in the research phase, and the shear strength of the structural surface when anchored in rock remains unknown.

[0004] Therefore, there is an urgent need for a method to calculate the shear strength of the structural surface under the anchoring of shear-type anchors, so as to quantitatively calculate and analyze the anchoring performance of shear-type anchors. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a method for calculating the shear strength of the structural surface under the anchoring of shear-type anchor rods, so as to solve the technical problems in the existing technology that there is no method for calculating the shear strength of the structural surface under the anchoring of shear-type anchor rods, and the anchoring performance of shear-type anchor rods cannot be quantitatively calculated and analyzed.

[0006] The technical solution adopted by the present invention is a method for calculating the shear strength of a structural surface anchored by a shear-type anchor rod, comprising the following steps:

[0007] Obtain the initial shear force, installation angle, diameter, length of the bending section, and elastic modulus of the shear anchor; obtain the compressive strength, normal stress, internal friction angle, cohesion, and reaction coefficient of the rock structure surface;

[0008] The rotation angle at the deformation point of the shear anchor is calculated based on the initial shear force, the length of the bending section, the elastic modulus, the moment of inertia of the anchor cross section, and the concentration of the reaction force of the rock mass along the length direction on the compression side of the anchor.

[0009] Calculate the axial component of the force on the shear anchor based on the rotation angle, initial shear force, diameter, and reaction concentration;

[0010] The calculated value of the tensile shear yield strength of the shear anchor is calculated based on the axial component, the cross-sectional area of ​​the shear anchor, and the initial shear force. The calculated value of the bending yield strength of the shear anchor is calculated based on the axial component, the bending moment value at the deformation point of the shear anchor, the cross-sectional area of ​​the shear anchor, and the bending cross-sectional modulus of the anchor.

[0011] The smaller of the calculated tensile shear yield strength and the calculated bending yield strength is used as the calculated yield strength of the shear anchor rod. Based on the calculated yield strength and the actual yield strength of the shear anchor rod, it is determined whether the anchor rod has yielded and failed. The shear force and the axial component of the force on the anchor rod are calculated when the anchor rod has yielded and failed.

[0012] The shear strength of the structural surface under the shear anchor is calculated based on the shear force the anchor withstands when it yields, the axial component of the force on the anchor, the normal stress, internal friction angle, cohesion of the rock mass, as well as the anchor installation angle and the cross-sectional area of ​​the anchor.

[0013] Furthermore, the concentration of the reaction force of the rock mass on the compression side of the anchor along the length direction is calculated based on the diameter of the shear anchor and the reaction force coefficient and compressive strength of the rock mass, as follows:

[0014]

[0015] In the above formula: p u is the concentration of the reaction force of the rock mass along the length direction on the compression side of the anchor, k is the reaction coefficient of the rock mass, is the compressive strength of the rock mass, and D is the diameter of the anchor rod.

[0016] Furthermore, the axial component of the shear anchor force is calculated according to the following formula:

[0017]

[0018] In the above formula: N0 is the axial component of the shear anchor force, is the rotation angle at the deformation point of the anchor rod, Q0 is the initial shear force, D is the diameter of the anchor rod, and p u It is the concentration of reaction force of the rock mass on the compression side of the anchor along the length direction.

[0019] Furthermore, the tensile shear yield strength is calculated according to the following formula:

[0020]

[0021] In the above formula: To calculate the tensile shear yield strength of the shear anchor, N0 is the axial component of the anchor force, A m is the cross-sectional area of ​​the anchor rod, and Q0 is the initial shear force.

[0022] Furthermore, the bending yield strength is calculated according to the following formula:

[0023]

[0024] In the above formula: To calculate the bending yield strength of the shear anchor, N0 is the axial component of the anchor force, M A is the bending moment value of the anchor rod at the deformation point A, W is the bending cross-sectional modulus of the anchor rod; A m is the cross-sectional area of ​​the anchor rod.

[0025] Furthermore, the shear force and the axial component of the anchor force that the anchor rod bears when yielding failure are calculated, including:

[0026] If the calculated yield strength of the anchor rod is greater than the actual yield strength of the anchor rod, the anchor rod has yielded and failed. The shear force and the axial component of the force on the anchor rod when it is failed can be obtained.

[0027] If the calculated value of the anchor rod yield strength is less than the actual value of the anchor rod yield strength, the anchor rod has not yielded; add a shear force of △Q0 to the initial shear force, and then calculate the new calculated value of the anchor rod yield strength, and then re-compare it with the actual value of the anchor rod yield strength until the anchor rod yields; when the shear-type anchor rod is allowed to yield, the shear force that the anchor rod bears when it is destroyed and the axial component of the anchor rod force can be obtained.

[0028] Furthermore, the shear strength of the structural surface anchored by the shear anchor is calculated according to the following formula:

[0029]

[0030] In the above formula, τ t is the natural shear strength between structural surface layers, τ N The shear strength provided by the axial component of the anchor force, τ Q The shear strength provided for the shear force exerted on the anchor rod.

[0031] Furthermore, the shear strength provided by the axial component of the anchor force is calculated according to the following formula:

[0032]

[0033] In the above formula, τ Nis the shear strength provided by the axial component of the anchor rod force, N1 is the axial component of the anchor rod force when yield failure occurs, α is the anchor rod installation angle, is the internal friction angle of the rock mass structural surface, A m is the cross-sectional area of ​​the anchor rod.

[0034] Furthermore, the shear strength provided by the shear force on the anchor rod is calculated according to the following formula:

[0035]

[0036] In the above formula, τ Q is the shear strength provided by the anchor rod under the shear force, Q1 is the shear force borne by the anchor rod when yield failure occurs, α is the anchor rod installation angle, is the internal friction angle of the structural surface, A m is the cross-sectional area of ​​the anchor rod.

[0037] It can be seen from the above technical solution that the beneficial technical effects of the present invention are as follows:

[0038] 1. Starting from the bedding rock slope where the shear anchor is anchored, and taking the initial shear force as the starting force, the shear strength of the structural surface under the shear anchor condition can be quantitatively calculated, and the anchoring effect of the shear anchor can be accurately evaluated.

[0039] 2. It can also evaluate the stability of layered rocks after anchoring, providing data reference to ensure the safety of slope anchoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0041] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of deformation of a rock mass structural surface according to an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of deformation of shear-type anchor rod according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following embodiments of the technical solution of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0045] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0046] Example

[0047] This embodiment provides a method for calculating the shear strength of the structural surface under the anchoring of shear-type anchor rods. Figure 1 As shown, the following steps are included:

[0048] S1. Obtain the initial shear force, installation angle, diameter, length of the bending section, and elastic modulus of the shear anchor; obtain the compressive strength, normal stress, internal friction angle, cohesion, and reaction coefficient of the rock structure surface

[0049] In this example, a rock slope along a road cutting in Chongqing was selected as the structural surface controlled slope. Due to the influence of toe excavation, the slope's stability decreased. Shear bolts were used to anchor the slope to enhance its stability. A landslide investigation was conducted on the structural surface controlled slope anchored by shear bolts.

[0050] During the landslide investigation of the slope, the slope deformation characteristic data and hydrological and geological engineering condition data were collected and summarized; the hydrological and geological engineering condition data include geological and geomorphological data, rock and soil physical and mechanical property data, ground stress data, meteorological and hydrological data, and construction data near the slope. After on-site investigation and comprehensive analysis, the bedding rock slope selected in this embodiment has the following characteristics: the initial shear force of the anchor is 40kN, the anchor installation angle α is 90°, the anchor diameter D is 25mm, the vertical load on a single anchor is 44kN, the elastic modulus E is 180GPa, and the actual yield strength σ of the anchor is 180GPa. e The compressive strength of the rock mass is 400 MPa. is 22MPa, internal friction angle The angle is 30° and the k reaction coefficient is 25. The normal stress σ and cohesion c of the rock mass structural surface are obtained through shear tests based on the soil samples of the rock mass.

[0051] S2. Calculate the rotation angle at the deformation point of the shear anchor according to the initial shear force of the shear anchor, the length of the bending section, the elastic modulus, the moment of inertia of the anchor cross section, and the concentration of the reaction force of the rock mass along the length direction on the compression side of the anchor.

[0052] In this embodiment, the shear strength calculation of the structural surface under the shear type anchor bolt needs to use the initial shear force as the starting force of the structural deformation and combine it with the angle at the anchor bolt deformation point to calculate. In order to calculate the angle at the anchor bolt deformation point, it is necessary to analyze the correlation between the anchor bolt deformation and the structural surface deformation. Figure 2 、 Figure 3As shown in the figure, a single anchored rock mass is selected for deformation and displacement analysis. The anchor deformation point is A. When the anchor installation angle α=90°, that is, the anchor is vertically fixed in the rock mass, the relationship between the anchor deformation and the structural surface deformation is: , , λ is the shear dilatancy angle of the structural surface, the unit is °; at this time, the axial deformation and lateral deformation of the anchor rod are consistent with the axial deformation and tangential deformation of the structural surface. According to the above analysis, the rotation angle at the deformation point A of the anchor rod is Calculate according to formula (1):

[0053] (1)

[0054] In the above formula (1): Q0 is the initial shear force, the unit is kN; l B is the length of the anchor rod bending section, in meters; E is the elastic modulus of the anchor rod; I is the moment of inertia of the anchor rod cross section; p u is the concentration of reaction force on the compression side of the anchor bolt in section AO along the length direction.

[0055] In a specific embodiment, the moment of inertia I of the cross section of the anchor is calculated based on the diameter D of the shear anchor, and the reaction coefficient k and compressive strength of the rock mass are calculated based on the diameter D of the shear anchor and the compressive strength of the rock mass. Calculate the concentration of reaction force of the rock mass along the length direction on the compression side of the anchor bolt; specifically, I, p u Calculate according to the following formulas (2) and (3):

[0056] (2)

[0057] (3)

[0058] In the above formulas (2) and (3): is the pi, D is the diameter of the anchor, the unit is m; k is the reaction coefficient of the rock mass, is the compressive strength of the rock mass, in kPa.

[0059] For the rock slope of a certain road cutting in Chongqing and the shear anchor selected in this embodiment, the rotation angle at the deformation point of the shear anchor can be calculated through this step. It is 18.9°.

[0060] S3. Calculate the axial component of the shear anchor force based on the rotation angle at the deformation point of the shear anchor, the initial shear force of the shear anchor, the diameter of the shear anchor, and the concentration of the reaction force of the rock mass along the length direction on the compression side of the anchor.

[0061] The axial component N0 of the anchor force is calculated according to formula (4):

[0062] (4)

[0063] In the above formula (4): is the rotation angle at the deformation point of the anchor rod, in degrees; Q0 is the initial shear force, in kN; D is the diameter of the anchor rod, in m; p u It is the concentration of reaction force of the rock mass on the compression side of the anchor along the length direction.

[0064] For a certain rock slope in a cutting in Chongqing and a shear anchor selected in this embodiment, the axial component N0 of the force on the shear anchor can be calculated to be 8.2 kN through this step.

[0065] S4. Calculate the tensile shear yield strength of the shear anchor based on the axial component of the force on the shear anchor, the cross-sectional area of ​​the shear anchor, and the initial shear force;

[0066] The bending yield strength of the shear anchor is calculated based on the axial component of the shear anchor force, the bending moment value at the deformation point of the shear anchor, the cross-sectional area of ​​the shear anchor, and the bending cross-sectional modulus of the anchor.

[0067] In a specific embodiment, the shearing yield strength calculation value of the shear anchor is

[0068] Calculate according to formula (5):

[0069] (5)

[0070] In the above formula (5), N0 is the axial component of the anchor force, the unit is kN; A m is the cross-sectional area of ​​the anchor rod, in m 2 ; Q0 is the initial shear force, unit is kN.

[0071] Calculated value of bending yield strength when shear anchor is bent and yielded Calculate according to formula (6):

[0072] (6)

[0073] In the above formula (6), N0 is the axial component of the anchor force, the unit is kN; M A is the bending moment value of the anchor rod at the deformation point A, the unit is kN·m; W is the bending cross-sectional modulus of the anchor rod; A m is the cross-sectional area of ​​the anchor rod, in m 2 .

[0074] In a specific embodiment, the bending cross-sectional modulus W of the anchor rod is calculated according to the following formula (7):

[0075] (7)

[0076] In the above formula (7), is pi, D is the diameter of the anchor rod, and the unit is m.

[0077] S5. The smaller of the calculated yield strength of the shear anchor and the calculated yield strength of the bending anchor is used as the calculated yield strength of the shear anchor. Based on the calculated yield strength and the actual yield strength, determine whether the anchor has yielded and failed. Calculate the shear force and the axial component of the force on the anchor when the anchor has yielded and failed.

[0078] In a specific embodiment, the tensile shear yield strength calculation value of the shear anchor is , Calculated value of bending yield strength Compare the two and take the smaller value as the yield strength calculation value σ of the shear anchor. el。

[0079] Determine whether the shear anchor has yielded. If the calculated yield strength of the anchor is σ el Greater than the actual value of anchor yield strength σ e , the anchor rod has yielded and failed; the shear force Q1 and the axial component N1 of the anchor rod force at this time can be obtained. el Less than the actual value of anchor yield strength σ e , then the anchor rod has not yielded. In this case, it is necessary to add a shear force of △Q0 to the initial shear force. According to formulas (5) and (6), the new anchor rod yield strength calculation value σ is obtained. el , and then compared with the actual value of anchor yield strength σ e The comparison is repeated until the anchor bolt yields and fails. When the shear anchor bolt yields and fails, the shear force Q1 and the axial component N1 of the anchor bolt force at the time of failure can be obtained.

[0080] For the rock slope of a certain road cutting in Chongqing and the shear anchor selected in this embodiment, the yield strength calculation value σ el After calculation and comparison of the values, it is 135.3MPa. The actual value of the anchor yield strength σ obtained in step S1 e The initial shear force is 400 MPa, and the anchor bolt does not yield in this case. Add △Q0 to the initial shear force and recalculate until the anchor bolt yields. When the shear anchor bolt yields, the shear force Q1 is 43.1 kN, and the axial component N1 of the anchor bolt force is 8.9 kN.

[0081] S6. Calculate the shear strength of the structural surface under the shear anchor according to the shear force, axial component of the anchor force, normal stress, internal friction angle, cohesion of the rock structure surface, anchor installation angle, and cross-sectional area of ​​the anchor.

[0082] In a specific embodiment, the shear strength of the structural surface under the shear anchor is calculated according to the following formula (8):

[0083] (8)

[0084] In the above formula (8), τ t is the natural shear strength between structural surface layers, unit is kPa; τ N The shear strength provided by the axial component of the anchor force, the unit is kPa; τ Q The shear strength provided by the anchor rod for the shear force, the unit is kPa.

[0085] Natural shear strength τ between structural surface layers t Calculate according to the following formula (9):

[0086] (9)

[0087] In the above formula (9), σ is the normal stress of the structural surface, and the unit is kN; is the internal friction angle of the structural surface, the unit is °; c is the cohesion of the structural surface, the unit is MPa.

[0088] Shear strength τ provided by the axial component of the anchor force N Calculate according to the following formula (10):

[0089] (10)

[0090] In the above formula (10), N1 is the axial component of the anchor force when yield failure occurs, the unit is kN; α is the anchor installation angle, the unit is °; is the internal friction angle of the structural surface, in degrees; A m is the cross-sectional area of ​​the anchor rod, in m 2 .

[0091] Shear strength τ provided by the shear force on the anchor Q Calculate according to the following formula (11):

[0092] (11)

[0093] In the above formula (11), Q1 is the shear force borne by the anchor when yield failure occurs, the unit is kN; α is the anchor installation angle, the unit is °; is the internal friction angle of the structural surface, in degrees; A m is the cross-sectional area of ​​the anchor rod, in m 2 .

[0094] For the rock slope along the bedding layer of a road cut in Chongqing and the shear anchor selected in this example, substituting the parameters in the previous steps into equations (8) to (11) for calculation, the shear strength of the structural surface anchored by the shear anchor was calculated to be 268.2 MPa. Based on actual engineering field tests, the shear strength of the structural surface anchored by the shear anchor was approximately 285.6 MPa, which is relatively close to the theoretical calculated value, with an error of only 6.3%. The theoretical calculated value has considerable reference value.

[0095] Through the technical solution of this embodiment, starting from the bedding rock slope where the shear type anchor is anchored, with the initial shear force as the starting force, the shear strength of the structural surface under the anchoring condition of the shear type anchor can be quantitatively calculated, and the anchoring effect of the shear type anchor can be accurately evaluated; the stability of the layered rock after anchoring can also be evaluated, providing data reference for ensuring the safety of slope anchoring.

[0096] 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 make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A method for calculating the shear strength of a structural surface anchored by a shear-type anchor, characterized in that: The following steps are involved: Obtain the initial shear force, installation angle, diameter, length of the bending section, and elastic modulus of the shear anchor; obtain the compressive strength, normal stress, internal friction angle, cohesion, and reaction coefficient of the rock structure surface; The rotation angle at the deformation point of the shear anchor is calculated based on the initial shear force, the length of the bending section, the elastic modulus, the moment of inertia of the anchor cross section, and the concentration of the reaction force of the rock mass on the compression side of the anchor along the length direction. The rotation angle is calculated according to the following formula: In the above formula: Q0 is the initial shear force, l B is the length of the anchor bolt bending section, E is the elastic modulus of the anchor bolt, I is the moment of inertia of the anchor bolt cross section, and p u is the concentration of reaction force along the length direction of the rock mass on the compression side of the anchor in the deformation section; Calculating the axial component of the force on the shear anchor according to the rotation angle, the initial shear force, the diameter, and the concentration of the reaction force; Calculate the calculated value of the tensile shear yield strength of the shear anchor according to the axial component, the cross-sectional area of ​​the shear anchor, and the initial shear force; calculate the calculated value of the bending yield strength of the shear anchor according to the axial component, the bending moment value at the deformation point of the shear anchor, the cross-sectional area of ​​the shear anchor, and the bending cross-sectional modulus of the anchor; The smaller of the calculated value of the tensile shear yield strength and the calculated value of the bending yield strength is used as the calculated yield strength value of the shear anchor rod, and whether the anchor rod has yielded is determined based on the calculated yield strength value and the actual yield strength value of the shear anchor rod, and the shear force and the axial component of the force on the anchor rod are calculated when the anchor rod has yielded; The shear strength of the structural surface under the shear anchor is calculated based on the shear force the anchor withstands when it yields, the axial component of the force on the anchor, the normal stress, internal friction angle, cohesion of the rock mass, as well as the anchor installation angle and the cross-sectional area of ​​the anchor.

2. The method for calculating the shear strength of the lower structural surface of the shear type anchor bolt according to claim 1 is characterized in that: The concentration of the reaction force of the rock mass on the compression side of the anchor rod along the length direction is calculated based on the diameter of the shear anchor rod and the reaction force coefficient and compressive strength of the rock mass, as follows: In the above formula: p u is the concentration of the reaction force of the rock mass along the length direction on the compression side of the anchor, k is the reaction coefficient of the rock mass, is the compressive strength of the rock mass, and D is the diameter of the anchor rod.

3. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 1 is characterized in that: The axial component of the shear anchor force is calculated according to the following formula: In the above formula: N0 is the axial component of the shear anchor force, is the rotation angle at the deformation point of the anchor rod, Q0 is the initial shear force, D is the diameter of the anchor rod, and p u It is the concentration of reaction force of the rock mass on the compression side of the anchor along the length direction.

4. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 1 is characterized in that: The tensile shear yield strength is calculated according to the following formula: In the above formula: To calculate the tensile shear yield strength of the shear anchor, N0 is the axial component of the anchor force, A m is the cross-sectional area of ​​the anchor rod, and Q0 is the initial shear force.

5. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 1 is characterized in that: The bending yield strength calculation value is calculated according to the following formula: In the above formula: To calculate the bending yield strength of the shear anchor, N0 is the axial component of the anchor force, M A is the bending moment value of the anchor rod at the deformation point A, W is the bending cross-sectional modulus of the anchor rod; A m is the cross-sectional area of ​​the anchor rod.

6. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 1 is characterized in that: Calculation of the shear force and axial component of the anchor force when the anchor yields, including: If the calculated yield strength of the anchor rod is greater than the actual yield strength of the anchor rod, the anchor rod has yielded and failed. The shear force and the axial component of the force on the anchor rod when it is failed can be obtained. If the calculated value of the anchor rod yield strength is less than the actual value of the anchor rod yield strength, the anchor rod has not yielded; a shear force with a value of △Q0 is added to the initial shear force, and then a new calculated value of the anchor rod yield strength is calculated, and then compared with the actual value of the anchor rod yield strength again until the anchor rod yields; when the shear-type anchor rod is allowed to yield, the shear force that the anchor rod bears when it is destroyed and the axial component of the anchor rod force can be obtained.

7. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 1 is characterized in that: The shear strength of the structural surface under the shear anchor is calculated according to the following formula: In the above formula, τ t is the natural shear strength between structural surface layers, τ N The shear strength provided by the axial component of the anchor force, τ Q The shear strength provided for the shear force exerted on the anchor rod.

8. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 7 is characterized in that: The shear strength provided by the axial component of the anchor force is calculated according to the following formula: In the above formula, τ N is the shear strength provided by the axial component of the anchor rod force, N1 is the axial component of the anchor rod force when yield failure occurs, α is the anchor rod installation angle, is the internal friction angle of the rock mass structural surface, A m is the cross-sectional area of ​​the anchor rod.

9. The method for calculating the shear strength of a structural surface anchored by a shear-type anchor according to claim 7, characterized in that: The shear strength provided by the shear force on the anchor rod is calculated according to the following formula: In the above formula, τ Q is the shear strength provided by the anchor rod under the shear force, Q1 is the shear force borne by the anchor rod when yield failure occurs, α is the anchor rod installation angle, is the internal friction angle of the structural surface, A m is the cross-sectional area of ​​the anchor rod.

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