A method for determining the bearing capacity of an anchor rod considering cement damage behavior

Abstract

This invention relates to a method for determining the load-bearing capacity of anchor bolts considering cementation damage behavior, belonging to the field of roadway surrounding rock control. The method includes calculating and determining the normal compressive stress at the anchorage interface between the anchor bolt and the anchoring agent; calculating the anchor bolt load-bearing capacity envelope, which is composed of the load-bearing capacity generated by the shear dilatation of the ribbed section of the anchor bolt and the load-bearing capacity generated by the cohesive force of the anchoring agent; dividing the anchor bolt loading process into two stages, including a pre-peak stage and a post-peak stage, defining the dynamic shear dilatation angle of the anchorage interface and the method for determining the cohesive force of the anchoring agent for the pre-peak and post-peak stages respectively; calculating the anchor bolt load-bearing capacity; and summarizing the calculated anchor bolt load-bearing capacity and the anchor bolt loading displacement results to plot the relationship curve between the anchor bolt load-bearing capacity and the anchor bolt loading displacement. Based on this invention, the load-bearing capacity of anchor bolts can be accurately calculated and the influence of cementation damage behavior on the load-bearing capacity of anchor bolts can be clarified, which is of great significance for revealing the anchoring mechanism of anchor bolt support.

Description

Technical Field

[0001] This invention belongs to the field of roadway surrounding rock control, and specifically relates to a method for determining the bearing capacity of anchor bolts considering cementation damage behavior. Background Technology

[0002] Rock bolt support is a commonly used anchoring technique in coal mine roadway surrounding rock control, playing a crucial role in ensuring the safe use of coal mine roadways. To clarify the load-bearing capacity of rock bolt support, previous researchers have conducted a series of indoor and field anchoring experiments. However, these experiments are often limited to clarifying the basic performance of rock bolt support from a macroscopic perspective, such as the maximum load-bearing capacity of the rock bolt. To further reveal the anchoring mechanism of rock bolt support, previous researchers have conducted theoretical analyses focusing on the load-bearing capacity of rock bolt support, establishing theoretical models that reflect this performance. Based on these theoretical models, researchers and engineers can study the influence of different parameters on the load-bearing capacity of rock bolt support under different working conditions, thereby predicting the load-bearing capacity of rock bolt support under different working conditions and providing a theoretical basis for the design of rock bolt support under complex working conditions.

[0003] However, previous theoretical analyses of the load-bearing capacity of anchor bolt supports still have certain problems, namely, neglecting the cementation damage behavior at the anchorage interface. Previous research results indicate that the load-bearing capacity of anchor bolt supports mainly comes from three aspects: cementation force, mechanical interlocking force, and frictional force. While previous theoretical analyses of the load-bearing capacity of anchor bolt supports considered mechanical interlocking force and frictional force, they generally neglected cementation force. Cementation force is reflected in the cohesive force within the mechanical parameters of the anchoring agent.

[0004] Previous studies generally overlooked the direct relationship between bonding force and the poor chemical bonding performance of early anchoring agents. However, with the rapid development of anchoring agent materials, the bonding performance of currently used anchoring agents has been significantly improved. Existing literature shows that the cohesion of modern silicate cement materials, measured based on conventional triaxial compression tests, can exceed 30 MPa. When the water-cement ratio is further changed, the cohesion of modern silicate cement materials can be further improved. Therefore, under these conditions, it is inappropriate to ignore the influence of bonding force on the anchor bolt's load-bearing capacity. Secondly, when bond failure occurs at the anchoring interface between the anchor bolt and the anchoring agent, due to the threaded structure on the anchor bolt surface, the shear-damaged anchoring agent adheres to the threads of the anchor bolt and, under normal confining pressure, interlocks into a whole, continuing to provide the anchor bolt's load-bearing capacity. Therefore, when bond failure occurs at the anchoring interface between the anchor bolt and the anchoring agent, there is bonding damage behavior at the anchoring interface. To date, few studies have considered bonding damage behavior in the process following bond failure at the anchoring interface between the anchor bolt and the anchoring agent. Therefore, existing research and technology have rarely addressed how to determine the load-bearing capacity of anchor bolts based on the cementation damage behavior.

[0005] To address the aforementioned problems, this invention proposes a method for determining the load-bearing capacity of anchor bolts that considers cementation damage behavior. This invention is of great significance for elucidating the cementation damage process following adhesion failure at the anchorage interface between the anchor bolt and the anchoring agent, and for revealing the anchoring mechanism of anchor bolt support. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the load-bearing capacity of anchor bolts that considers cementation damage behavior. This method overcomes the deficiency of previous methods in effectively considering cementation damage behavior at the anchorage interface when calculating the load-bearing capacity of anchor bolts. Therefore, users can effectively calculate and determine the load-bearing capacity of anchor bolts when using this invention.

[0007] This invention provides a method for determining the load-bearing capacity of anchor bolts that considers cementation damage behavior, comprising the following steps:

[0008] S1: Calculate and determine the normal compressive stress at the anchorage interface between the anchor bolt and the anchoring agent using the following formula: , in the formula, This refers to the normal compressive stress at the anchoring interface between the anchor bolt and the anchoring agent. The Poisson's ratio of the anchoring agent; The radius of the outer ring of the anchoring agent; The normal compressive stress at the anchoring interface between the anchoring agent and the surrounding rock; Where is the anchor bolt radius;

[0009] S2: Calculate the anchor bolt bearing capacity envelope using the following formula: , in the formula, This is the envelope of the anchor bolt's bearing capacity. This refers to the bearing capacity generated by the shear expansion of the ribbed section of the anchor bolt. This is the bearing capacity generated by the cohesive force of the anchoring agent;

[0010] The bearing capacity of the ribbed section of the anchor bolt due to shear dilatation is calculated using the following formula: , in the formula, This refers to the length of the anchorage section of the anchor bolt. The width of a single transverse rib on the anchor bolt surface; The width between two adjacent transverse ribs on the anchor bolt surface; The internal friction angle of the anchoring agent; For the dynamic shear dilatation angle of the anchoring interface;

[0011] The bearing capacity generated by the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, For the cohesive force of the anchoring agent;

[0012] S3: The anchor bolt loading process is divided into two stages, including the pre-peak stage and the post-peak stage;

[0013] During the pre-peak stage, the dynamic shear dilatation angle of the anchorage interface is calculated using the following formula: , in the formula, The inclination angle of the transverse ribs on the anchor bolt surface; Apply displacement to the anchor bolt;

[0014] During the pre-peak stage, the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, For the cohesive force of the anchoring agent;

[0015] In the post-peak stage, the dynamic shear dilatation angle of the anchorage interface is calculated using the following formula: , in the formula, This refers to the dynamic shear dilatation angle of the anchorage interface when the anchor bolt's bearing capacity reaches its maximum. This represents the anchor rod loading displacement corresponding to the maximum bearing capacity of the anchor rod in the physical experiment data.

[0016] In the post-peak stage, the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, The coefficient representing the influence of the cohesive force of the anchoring agent; The cohesive shrinkage coefficient of the anchoring agent;

[0017] S4: Calculate the anchor bolt bearing capacity using the following formula: , in the formula, For the first The bearing capacity of each anchor bolt; For the first The bearing capacity of each anchor bolt; The bonding stiffness of the anchoring interface between the anchor bolt and the anchoring agent; Apply displacement increments to the anchor bolts;

[0018] S5: Summarize the calculated anchor bearing capacity and anchor loading displacement results, and plot the anchor bearing capacity versus anchor loading displacement curve with the anchor bearing capacity as the vertical axis and the anchor loading displacement as the horizontal axis.

[0019] As a further description of the above technical solution:

[0020] During the pre-peak stage, when the anchor bolt bearing capacity reaches its maximum, the dynamic shear dilatation angle at the anchorage interface is calculated using the following formula: .

[0021] As a further description of the above technical solution:

[0022] The influence coefficient of anchoring agent cohesion ranges from [0, 1]; the reference value of the influence coefficient of anchoring agent cohesion can be calculated using the following formula: , in the formula, This is a reference value for the influence coefficient of the cohesive force of the anchoring agent; This refers to the anchor bearing capacity corresponding to the maximum value of the anchor load displacement in the physical experiment data. This represents the maximum bearing capacity of the anchor bolt in the physical experiment data;

[0023] When using it, the cohesive force influence coefficient of the anchoring agent can be dynamically corrected within the range of [0, 1] based on the reference value of the cohesive force influence coefficient of the anchoring agent until the theoretical calculation results are consistent with the physical experimental results.

[0024] As a further description of the above technical solution:

[0025] The lower limit of the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent can be calculated using the following formula: , in the formula, This is the lower limit of the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent. In use, after calculating the lower limit of the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent, the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent can be dynamically increased until the peak pre-curve obtained by theoretical calculation is consistent with the peak pre-curve in physical experiment.

[0026] As a further description of the above technical solution:

[0027] In the pre-peak stage, the initial value of the anchor bolt bearing capacity is 0; in the post-peak stage, the initial value of the anchor bolt bearing capacity is the bearing capacity of the last anchor bolt in the pre-peak stage.

[0028] Beneficial effects

[0029] The main beneficial effects of this invention include:

[0030] (1) To address the bonding failure process at the anchorage interface between the anchor bolt and the anchoring agent, this invention proposes a formulaic equation that reflects the bonding damage behavior at the anchorage interface. This formulaic equation effectively considers the contribution of bonding force to the anchor bolt's bearing capacity. Furthermore, it effectively simulates the gradual disappearance of bonding force after bonding failure at the anchorage interface between the anchor bolt and the anchoring agent, thereby accurately simulating the post-peak bearing capacity of the anchor bolt support.

[0031] (2) The proposed formulaic equation is an exponential equation. Therefore, when using this invention to calculate the anchor bearing capacity, for the post-peak stage, considering the cementation damage behavior, the anchor bearing capacity reduction process can be simulated in a nonlinear manner. This method overcomes the defect of previous methods using bilinear or trilinear bond-slip models to simulate anchor bearing capacity, where the anchor bearing capacity only decreases linearly in the post-peak stage.

[0032] (3) This invention proposes two parameters: the cohesive force influence coefficient of the anchoring agent and the cohesive force shrinkage coefficient of the anchoring agent. By adjusting these two parameters, the anchor bearing capacity can decrease nonlinearly at different degrees. Therefore, the anchor bearing capacity calculation method proposed in this invention has flexible degrees of freedom. By adjusting these two parameters, the theoretical calculation results can be better matched with the physical experimental results.

[0033] (4) This invention provides the range of values ​​for the anchoring agent cohesion influence coefficient and a reference value for the anchoring agent cohesion influence coefficient. Therefore, based on the reference value of the anchoring agent cohesion influence coefficient, users can dynamically adjust the anchoring agent cohesion influence coefficient within the range of values. This overcomes the problem of the inability to effectively determine the input parameter value.

[0034] (5) This invention provides a lower limit for the bonding stiffness of the anchorage interface between the anchor bolt and the anchoring agent. Therefore, when using this invention, users can dynamically increase the bonding stiffness of the anchorage interface between the anchor bolt and the anchoring agent based on this lower limit, thus ensuring that the theoretical calculation results and physical experimental results match in the pre-peak stage. This reduces the range of values ​​for the bonding stiffness of the anchorage interface between the anchor bolt and the anchoring agent, overcoming the problem that the range of values ​​for the bonding stiffness of the anchorage interface between the anchor bolt and the anchoring agent is too large and cannot be effectively determined. Attached Figure Description

[0035] The accompanying drawings, which constitute a part of this application, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 This is a flowchart illustrating the calculation process for determining the bearing capacity of an anchor bolt that considers cementation damage behavior, as proposed in this invention.

[0037] Figure 2 This is a comparison chart of the calculation results and physical experiment results of this invention.

[0038] Figure 3 This is a graph showing the effect of the anchoring agent cohesion influence coefficient on the anchor bolt bearing capacity, calculated based on this invention.

[0039] Figure 4 This is a graph showing the effect of the cohesive shrinkage coefficient of the anchoring agent on the bearing capacity of the anchor bolt, calculated based on this invention. Detailed Implementation

[0040] like Figure 1 As shown, the present invention provides a method for determining the load-bearing capacity of an anchor bolt considering cementation damage behavior, comprising the following steps:

[0041] S1: Calculate and determine the normal compressive stress at the anchorage interface between the anchor bolt and the anchoring agent using the following formula: , in the formula, This refers to the normal compressive stress at the anchoring interface between the anchor bolt and the anchoring agent. The Poisson's ratio of the anchoring agent; The radius of the outer ring of the anchoring agent; The normal compressive stress at the anchoring interface between the anchoring agent and the surrounding rock; Where is the anchor bolt radius;

[0042] S2: Calculate the anchor bolt bearing capacity envelope using the following formula: , in the formula, This is the envelope of the anchor bolt's bearing capacity. This refers to the bearing capacity generated by the shear expansion of the ribbed section of the anchor bolt. This is the bearing capacity generated by the cohesive force of the anchoring agent;

[0043] The bearing capacity of the ribbed section of the anchor bolt due to shear dilatation is calculated using the following formula: , in the formula, This refers to the length of the anchorage section of the anchor bolt. The width of a single transverse rib on the anchor bolt surface; The width between two adjacent transverse ribs on the anchor bolt surface; The internal friction angle of the anchoring agent; For the dynamic shear dilatation angle of the anchoring interface;

[0044] The bearing capacity generated by the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, For the cohesive force of the anchoring agent;

[0045] S3: The anchor bolt loading process is divided into two stages, including the pre-peak stage and the post-peak stage;

[0046] During the pre-peak stage, the dynamic shear dilatation angle of the anchorage interface is calculated using the following formula: , in the formula, The inclination angle of the transverse ribs on the anchor bolt surface; Apply displacement to the anchor bolt;

[0047] During the pre-peak stage, the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, For the cohesive force of the anchoring agent;

[0048] In the post-peak stage, the dynamic shear dilatation angle of the anchorage interface is calculated using the following formula: , in the formula, This refers to the dynamic shear dilatation angle of the anchorage interface when the anchor bolt's bearing capacity reaches its maximum. This represents the anchor rod loading displacement corresponding to the maximum bearing capacity of the anchor rod in the physical experiment data.

[0049] In the post-peak stage, the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, The coefficient representing the influence of the cohesive force of the anchoring agent; The cohesive shrinkage coefficient of the anchoring agent;

[0050] S4: Calculate the anchor bolt bearing capacity using the following formula: , in the formula, For the first The bearing capacity of each anchor bolt; For the first The bearing capacity of each anchor bolt; The bonding stiffness of the anchoring interface between the anchor bolt and the anchoring agent; Apply displacement increments to the anchor bolts;

[0051] S5: Summarize the calculated anchor bearing capacity and anchor loading displacement results, and plot the anchor bearing capacity versus anchor loading displacement curve with the anchor bearing capacity as the vertical axis and the anchor loading displacement as the horizontal axis.

[0052] In one specific embodiment:

[0053] During the pre-peak stage, when the anchor bolt bearing capacity reaches its maximum, the dynamic shear dilatation angle at the anchorage interface is calculated using the following formula: .

[0054] In one specific embodiment:

[0055] The influence coefficient of anchoring agent cohesion ranges from [0, 1]; the reference value of the influence coefficient of anchoring agent cohesion can be calculated using the following formula: , in the formula, This is a reference value for the influence coefficient of the cohesive force of the anchoring agent; This refers to the anchor bearing capacity corresponding to the maximum value of the anchor load displacement in the physical experiment data. This represents the maximum bearing capacity of the anchor bolt in the physical experiment data;

[0056] When using it, the cohesive force influence coefficient of the anchoring agent can be dynamically corrected within the range of [0, 1] based on the reference value of the cohesive force influence coefficient of the anchoring agent until the theoretical calculation results are consistent with the physical experimental results.

[0057] In one specific embodiment:

[0058] The lower limit of the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent can be calculated using the following formula: , in the formula, This is the lower limit of the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent. In use, after calculating the lower limit of the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent, the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent can be dynamically increased until the peak pre-curve obtained by theoretical calculation is consistent with the peak pre-curve in physical experiment.

[0059] In one specific embodiment:

[0060] In the pre-peak stage, the initial value of the anchor bolt bearing capacity is 0; in the post-peak stage, the initial value of the anchor bolt bearing capacity is the bearing capacity of the last anchor bolt in the pre-peak stage.

[0061] To verify the effectiveness of this invention, an anchoring experiment was conducted in the laboratory, and the results were used to verify the calculation results of this invention. The anchor rod radius was 12.5 mm, and the outer radius of the anchoring agent ring was 25 mm. Measurements of the anchor rod surface revealed that the width of a single transverse rib was 2.5 mm, the width between two adjacent transverse ribs was 7.5 mm, the transverse rib inclination angle was 25°, and the anchoring section length was 140 mm. In the anchoring experiment, a normal compressive stress of 1 MPa was applied to the anchor rod and anchoring agent using a pressure chamber. The anchor rod bearing capacity and the anchor rod loading displacement were recorded during the anchoring experiment, obtaining the anchor rod bearing capacity as a function of the anchor rod loading displacement.

[0062] This invention is used to calculate the relationship curve between the anchor bolt bearing capacity and the anchor bolt loading displacement. Referring to the basic mechanical properties of anchoring agents in existing literature, the Poisson's ratio of the anchoring agent is set to 0.21 in this calculation. Therefore, the normal compressive stress at the anchoring interface between the anchor bolt and the anchoring agent is calculated and determined to be 1.32 MPa.

[0063] Calculate the anchor bolt bearing capacity envelope. When calculating the anchor bolt bearing capacity envelope, the internal friction angle of the anchoring agent is set to 15.1°.

[0064] The anchor bolt loading process is divided into two stages: the pre-peak stage and the post-peak stage. In the pre-peak stage, the anchoring agent cohesion is set at 31.4 MPa. The anchor bolt loading displacement is set to 1.48 mm when the anchor bolt bearing capacity reaches its maximum. Therefore, the range of anchor bolt loading displacement in the pre-peak stage is [0, 1.48]. In the post-peak stage, the dynamic shear dilatation angle of the anchoring interface is calculated to be 24.96° when the anchor bolt bearing capacity reaches its maximum. The range of the anchoring agent cohesion influence coefficient is defined as [0, 1]. The reference value for the anchoring agent cohesion influence coefficient is calculated to be 0.28. Based on this reference value, the anchoring agent cohesion influence coefficient is dynamically adjusted to 0.22 when comparing theoretical calculation results and physical experimental results. The anchoring agent cohesion shrinkage coefficient is set to 80.

[0065] Calculate the anchor bolt bearing capacity. The lower limit of the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent is calculated to be 108.5 kN / mm. Based on this lower limit, when comparing the pre-peak curve in theoretical analysis with the pre-peak curve in physical experiments, the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent is gradually increased to 145 kN / mm. In the pre-peak stage, the initial anchor bolt bearing capacity is 0; in the post-peak stage, the initial anchor bolt bearing capacity is the bearing capacity of the last anchor bolt in the pre-peak stage, i.e., 160.2 kN. The anchor bolt loading displacement increment is set to 1.48 μm.

[0066] Summarizing the calculation results, a curve was plotted showing the relationship between anchor bolt bearing capacity and anchor bolt loading displacement, with anchor bolt bearing capacity as the ordinate and anchor bolt loading displacement as the abscissa. The theoretical calculation results were then compared with the physical experimental results. Figure 2 As shown in the figure, the maximum bearing capacity of the anchor bolt in the physical experiment was 160.3 kN, while the maximum bearing capacity of the anchor bolt calculated by this invention was 160.2 kN, which is highly consistent with the physical experiment results. Furthermore, in both the pre-peak and post-peak stages, the relationship curve between the anchor bolt bearing capacity and the anchor bolt loading displacement calculated by this invention is highly consistent with the law shown in the physical experiment results, fully verifying the effectiveness of this invention.

[0067] based on Figure 2 It can be seen that the formulaic equation proposed in this invention, which reflects the bonding damage behavior at the anchorage interface between the anchor bolt and the anchoring agent, can effectively simulate the gradual disappearance of the bonding force after the anchorage interface between the anchor bolt and the anchoring agent fails, thus accurately simulating the post-peak load-bearing performance of the anchor bolt support. Furthermore, for the post-peak stage, the anchor bolt bearing capacity calculated by this invention decreases in a non-linear manner, overcoming the deficiency of traditional bilinear or trilinear models that can only simulate the decrease in anchor bolt bearing capacity in a linear manner.

[0068] To clarify the applicability of this invention, based on the above parameters, the cohesive force influence coefficients of the anchoring agent were set to 0.1, 0.2, and 0.3, respectively, and the relationship curves between the anchor bolt bearing capacity and the anchor bolt loading displacement were obtained, as shown below. Figure 3 As shown, the cohesive force influence coefficient of the anchoring agent has a significant impact on the anchor bolt bearing capacity in the post-peak stage. When the cohesive force influence coefficient is small, the anchor bolt bearing capacity decreases rapidly in the post-peak stage; when the cohesive force influence coefficient is large, the anchor bolt bearing capacity decreases slowly in the post-peak stage. Therefore, as the cohesive force influence coefficient of the anchoring agent increases, the rate of decrease in anchor bolt bearing capacity gradually slows down in the post-peak stage. Figure 3 This indicates that when calculating the anchor bolt bearing capacity using this invention, the anchor bolt bearing capacity has flexible degrees of freedom in the post-peak stage, and can decrease at different rates within a certain range. Taking this case as an example, in the post-peak stage, if the anchor bolt bearing capacity falls below a certain threshold in the physical experiment... Figure 3Between the bottommost and topmost curves, the cohesive force influence coefficient of the anchoring agent can be adjusted to ensure that the theoretical calculation results match the physical experimental results.

[0069] Furthermore, based on the above parameters, the cohesive shrinkage coefficients of the anchoring agent were set to 100, 300, and 1000, respectively, to obtain the relationship curves between the anchor bolt bearing capacity and the anchor bolt loading displacement, as shown below. Figure 4 As shown, the cohesive shrinkage coefficient of the anchoring agent also affects the anchor bolt bearing capacity in the post-peak stage. With the increase of the cohesive shrinkage coefficient of the anchoring agent, the decrease in anchor bolt bearing capacity gradually increases in the post-peak stage. Figure 4 This also shows that, in the post-peak stage, when calculating the anchor bolt bearing capacity using this invention, the anchor bolt anchoring force can decrease within a certain range at different rates. Taking this case as an example, if the anchor bolt bearing capacity falls within a certain range during the physical experiment... Figure 4 Between the bottom and top curves, the cohesive shrinkage coefficient of the anchoring agent can be adjusted to ensure that the theoretical calculation results match the physical experimental results.

[0070] Combination Figure 3 and Figure 4 As can be seen, when using this invention to calculate the anchor bolt bearing capacity, the user can adjust the two parameters: the anchoring agent cohesion influence coefficient and the anchoring agent cohesion shrinkage coefficient. This allows the anchor bolt bearing capacity to decrease at different rates after the peak. Therefore, the anchor bolt bearing capacity determination method proposed in this invention has flexible degrees of freedom and can be matched with physical experimental results relatively more easily.

[0071] Furthermore, based on this invention, a reference value for the cohesive force influence coefficient of the anchoring agent can be calculated. Using this as a basis, the cohesive force influence coefficient can be adjusted within its range to ensure that the theoretical calculation results match the physical results. This overcomes the problem of not being able to effectively determine the values ​​of the input parameters.

[0072] Finally, when using this invention to calculate the load-bearing capacity of anchor bolts, the lower limit of the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent can be calculated. Based on this, the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent is dynamically increased until the theoretical calculation results match the physical experimental results in the pre-peak stage. This overcomes the problem that the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent has an excessively large range and cannot be effectively determined.

[0073] This invention is not limited to the preferred embodiments described above. Anyone can derive other forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for determining the load bearing performance of an anchor rod taking into account the behavior of cement damage, characterized in that, Includes the following steps: S1: Calculate and determine the normal compressive stress at the anchorage interface between the anchor bolt and the anchoring agent using the following formula: , in the formula, This refers to the normal compressive stress at the anchoring interface between the anchor bolt and the anchoring agent. The Poisson's ratio of the anchoring agent; The radius of the outer ring of the anchoring agent; The normal compressive stress at the anchoring interface between the anchoring agent and the surrounding rock; Where is the anchor bolt radius; S2: Calculate the anchor bolt bearing capacity envelope using the following formula: , in the formula, This is the envelope of the anchor bolt's bearing capacity. This refers to the bearing capacity generated by the shear expansion of the ribbed section of the anchor bolt. This is the bearing capacity generated by the cohesive force of the anchoring agent; The bearing capacity of the ribbed section of the anchor bolt due to shear dilatation is calculated using the following formula: , in the formula, This refers to the length of the anchorage section of the anchor bolt. The width of a single transverse rib on the anchor bolt surface; The width between two adjacent transverse ribs on the anchor bolt surface; The internal friction angle of the anchoring agent; For the dynamic shear dilatation angle of the anchoring interface; The bearing capacity generated by the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, For the cohesive force of the anchoring agent; S3: The anchor bolt loading process is divided into two stages, including the pre-peak stage and the post-peak stage; During the pre-peak stage, the dynamic shear dilatation angle of the anchorage interface is calculated using the following formula: , in the formula, The inclination angle of the transverse ribs on the anchor bolt surface; Apply displacement to the anchor bolt; During the pre-peak stage, the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, For the cohesive force of the anchoring agent; In the post-peak stage, the dynamic shear dilatation angle of the anchorage interface is calculated using the following formula: , in the formula, This refers to the dynamic shear dilatation angle of the anchorage interface when the anchor bolt's bearing capacity reaches its maximum. This represents the anchor rod loading displacement corresponding to the maximum bearing capacity of the anchor rod in the physical experiment data. In the post-peak stage, the cohesive force of the anchoring agent is calculated using the following formula: , in the formula, The coefficient representing the influence of the cohesive force of the anchoring agent; The cohesive shrinkage coefficient of the anchoring agent; S4: Calculate the anchor bolt bearing capacity using the following formula: , in the formula, For the first The bearing capacity of each anchor bolt; For the first The bearing capacity of each anchor bolt; The bonding stiffness of the anchoring interface between the anchor bolt and the anchoring agent; Apply displacement increments to the anchor bolts; S5: Summarize the calculated anchor bearing capacity and anchor loading displacement results, and plot the anchor bearing capacity versus anchor loading displacement curve with the anchor bearing capacity as the vertical axis and the anchor loading displacement as the horizontal axis.

2. The method for determining the bearing capacity of an anchor bolt considering cementation damage behavior according to claim 1, characterized in that, During the pre-peak stage, when the anchor bolt bearing capacity reaches its maximum, the dynamic shear dilatation angle at the anchorage interface is calculated using the following formula: .

3. The method for determining the bearing capacity of an anchor bolt considering cementation damage behavior according to claim 1, characterized in that, The influence coefficient of anchoring agent cohesion ranges from [0, 1]; the reference value of the influence coefficient of anchoring agent cohesion is calculated using the following formula: , in the formula, This is a reference value for the influence coefficient of the cohesive force of the anchoring agent; This refers to the anchor bearing capacity corresponding to the maximum value of the anchor load displacement in the physical experiment data. This represents the maximum bearing capacity of the anchor bolt in the physical experiment data; When in use, the cohesive force influence coefficient of the anchoring agent is dynamically corrected within the range of [0, 1] based on the reference value of the cohesive force influence coefficient of the anchoring agent until the theoretical calculation results are consistent with the physical experimental results.

4. The method for determining the bearing capacity of an anchor bolt considering cementation damage behavior according to claim 3, characterized in that, The lower limit of the bond stiffness at the anchorage interface between the anchor bolt and the anchoring agent is calculated using the following formula: , in the formula, This is the lower limit of the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent. In use, after calculating the lower limit of the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent, the bonding stiffness of the anchoring interface between the anchor rod and the anchoring agent is dynamically increased until the peak pre-curve obtained by theoretical calculation is consistent with the peak pre-curve in physical experiment.

5. The method for determining the bearing capacity of an anchor bolt considering cementation damage behavior according to claim 1, characterized in that, In the pre-peak stage, the initial value of the anchor bolt bearing capacity is 0; in the post-peak stage, the initial value of the anchor bolt bearing capacity is the bearing capacity of the last anchor bolt in the pre-peak stage.

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