Calculation method for analyzing tensile bearing characteristics of anchor rod

Abstract

The invention discloses a calculation method for analyzing the tensile bearing characteristic of an anchor rod, and belongs to the field of numerical calculation of roadway support. The method comprises the seven steps of generating an anchor unit, defining a large deformation calculation mode, defining an attribute parameter, defining a fish function'inisise ', executing the fish function'inisise', defining a fish function'modifying ', and executing the fish function'modifying'. The bearing process after the anchor unit is pulled is divided into an elastic stage, a yield stage, a strain hardening stage, a strain softening stage and a fracture stage. According to the method, a yield stage formula, a strain hardening stage formula and a strain softening stage formula are provided, and the formulas are embedded into a fish function'modifying '. The yield characteristic, the strain hardening characteristic and the strain softening characteristic of the anchor unit can be simulated based on the fish function'modifying '. According to the invention, a fracture stage is designed for the anchor unit. And when the anchor unit is pulled and enters a fracture stage, the bearing capacity of the anchor unit is instantaneously reduced to zero. Compared with original anchor unit calculation, the method can better simulate the tensile bearing characteristics of the anchor rod.

Description

Technical Field

[0001] The invention belongs to the field of numerical calculation of tunnel support, and in particular relates to a calculation method for analyzing the tensile bearing characteristics of anchor rods. Background Art

[0002] The anchor unit is a structural unit in the three-dimensional finite difference numerical calculation software FLAC3D. The anchor unit takes into account the contact relationship between the anchor and the surrounding rock, can simulate the mechanical transmission process between the anchor and the surrounding rock, and is widely used in the field of numerical calculation of tunnel support.

[0003] However, it can be seen from the FLAC3D manual that in order to simplify the calculation, FLAC3D simplifies the anchor unit into an ideal elastic-plastic model and simulates the tensile bearing characteristics of the anchor rod. Based on this assumption, when the anchor rod is simulated using the anchor unit, when the anchor rod is stretched, as the tensile displacement increases, the tension in the anchor rod increases linearly to the tensile limit; then, as the tensile displacement continues to increase, the tension in the anchor rod remains constant.

[0004] By conducting tensile tests on anchor rods and obtaining load-tensile displacement curves, it can be seen that the load-tensile displacement curve of the anchor rod after being stretched can be divided into five stages in detail: elastic stage, yield stage, strengthening stage, local deformation stage, and breaking stage.

[0005] Comparing the simulation results of anchor units with the tensile test results of anchor rods, it can be seen that there are the following deficiencies when using anchor units to simulate anchor rods:

[0006] (1) The anchor unit uses an ideal elastic-plastic model to simulate the anchor rod, which oversimplifies the tensile bearing characteristics of the anchor rod. The anchor unit takes into account the linear elastic deformation characteristics of the anchor rod after loading. Therefore, when the anchor rod is stretched, the anchor unit can better reflect the linear elastic deformation characteristics of the anchor rod. However, after the linear elastic deformation of the anchor rod ends, the anchor unit uses an ideal plastic model to simulate the yielding behavior, strain hardening behavior, strain softening behavior and breaking behavior of the anchor rod. This is obviously inconsistent with the tensile bearing characteristics of the anchor rod in the experiment.

[0007] (2) The anchor unit simplifies the anchor yield load and the anchor tensile limit into the same force, which cannot reflect the difference between the anchor yield load and the anchor tensile limit. The experimental results show that the anchor tensile limit is significantly greater than the anchor yield load. Therefore, the use of the anchor unit cannot reflect the difference between the anchor yield load and the anchor tensile limit.

[0008] (3) The anchor unit does not consider the strain hardening and strain softening characteristics of the anchor rod. The results of the anchor rod tensile test show that the anchor rod will exhibit strain hardening characteristics after the yield stage, that is, as the tensile displacement increases, the anchor rod tension increases nonlinearly to the tensile limit. After reaching the tensile limit, as the tensile displacement continues to increase, the anchor rod tension decreases nonlinearly, showing strain softening characteristics. The above two characteristics are not considered when the anchor unit simulates the anchor rod.

[0009] (4) The anchor unit does not consider the breaking characteristics of the anchor rod. The results of the anchor rod tensile test show that after the local deformation stage ends, the anchor rod will break as the tensile displacement continues to increase. At this time, the bearing capacity of the anchor rod drops rapidly to zero. The anchor unit uses an ideal plastic model to simulate the anchor rod. Based on this model, the anchor rod simulated by the anchor unit will not break, but will only show a phenomenon in which the post-peak tensile displacement continues to increase and the tension remains constant. This is obviously inconsistent with the actual bearing performance of the anchor rod.

[0010] In view of the above problems, the present invention provides a calculation method for analyzing the tensile bearing characteristics of anchor rods based on a modified anchor unit. The calculation method can take into account the linear elastic characteristics, yield characteristics, strain hardening characteristics, strain softening characteristics, and breaking characteristics of the anchor rod during tension, and can be well used in the analysis of the tensile bearing performance of anchor rods. Summary of the invention

[0011] The purpose of the present invention is to provide a calculation method for analyzing the tensile bearing characteristics of anchor rods. The method improves the defect that the original anchor unit in FLAC3D cannot effectively simulate the tensile bearing characteristics of anchor rods.

[0012] The present invention adopts the following technical scheme to provide a calculation method for analyzing the tensile bearing characteristics of anchor rods, including generating anchor units, defining large deformation calculation modes, defining attribute parameters, defining fish function "initialise", executing fish function "initialise", defining fish function "modifying", and executing fish function "modifying".

[0013] As a further description of the above technical solution: when generating an anchor unit, three parameters, namely, the anchor unit starting point, the anchor unit end point, and the number of anchor units, need to be defined, and the number of anchor units must be greater than 1.

[0014] As a further description of the above technical solution: when defining the large deformation calculation mode, the large deformation calculation mode is "false".

[0015] As a further description of the above technical solution: the attribute parameters include eleven parameters, including "s2_times", "s3_variable", "s3_power", "s3_interval", "s4_increment", "s4_coefficient", "s5_disp", "recording_flag", "stage_flag", "yield_force", and "tensile_failure_force"; the "s2_times" parameter is the ratio of the tensile displacement at the end of the yield stage of the anchor to the tensile displacement at the beginning of the yield stage; the "s3_variable" parameter, the "s3_power" parameter, and the "s3_interval" parameter are respectively "s4_increment" and "s4_coefficient" are the relative initial value of strain softening and the strain softening contraction coefficient, respectively; "s5_disp" is the tensile displacement corresponding to the bolt breaking; "recording_flag", "stage_flag", "yield_force" and "tensile_failure_force" are the recording state parameter, stage state parameter, bolt yield force and bolt tensile limit, respectively; "s4_increment" and "recording_flag" are both set to 0; "stage_flag" is set to 1.

[0016] As a further description of the above technical solution: the logical structure of the fish function "initialise" is as follows: based on the pointer variable pnt, each anchor unit is traversed, and the following operations are performed during the traversal process: the "yield_force" parameter is assigned to the "struct.cable.yield.tension" function; the calculation result of the first formula is assigned to the "struct.cable.area" function; the Young's modulus value of the anchor rod is assigned to the "struct.cable.young" function; the bond stiffness value of the anchor interface is assigned to the "struct.cable.grout.stiffness" function.

[0017] As a further description of the above technical solution: the logical structure of the fish function "modifying" is as follows: the fish function "modifying" is executed at each time step; the unbalanced force at the tensile end of the anchor unit along the tensile direction is taken out and assigned to the "force" variable, the tensile displacement at the tensile end of the anchor unit along the tensile direction is taken out and assigned to the "disp" variable; the first first-level judgment process is executed; the second first-level judgment process is executed.

[0018] As a further description of the above technical solution: the fish function "modifying" is executed at each time step.

[0019] As a further description of the above technical solution: the first level judgment process is to judge whether the "force" variable is greater than or equal to the "yield_force" parameter; if the first level judgment is yes, the first level judgment is carried out, that is, to judge whether the "recording_flag" parameter is zero; if the first level judgment is yes, the "disp" variable is assigned to the "disp_stage2_start" variable, the result of the second formula is assigned to the "disp_stage2_end" variable, 1 is assigned to the "recording_flag" variable, 2 is assigned to the "stage_flag" variable and the first level judgment is ended; the second level judgment is carried out to judge whether the "disp" variable is greater than the "disp_stage 2_end" variable. If the second secondary judgment is yes, the third level judgment is carried out, that is, whether the "force" variable is less than the "tensile_failure_force" parameter. If the third level judgment is yes, the fourth level judgment is carried out, that is, whether the "stage_flag" variable is less than 4. If the fourth level judgment is yes, each anchor unit is traversed based on the pointer variable pnt. During the traversal process, the calculation result of the third formula is assigned to the "struct.cable.yield.tension" function; the calculation result of the fourth formula is assigned to the "s3_variable" variable and the fourth level judgment is ended; if the third level judgment is no, 4 is assigned to the "stage_flag" variable and the third level judgment is ended; the second secondary judgment is ended; the first primary judgment is ended.

[0020] As a further description of the above technical solution: the second first-level judgment process is to judge whether the "stage_flag" parameter is equal to 4; if the second first-level judgment is yes, execute the third second-level judgment, that is, judge whether the "disp" variable is less than or equal to the "s5_disp" parameter. If the third second-level judgment is yes, traverse each anchor unit based on the pointer variable pnt, and assign the result of the fifth formula calculation to the "struct.cable.yield.tension" function during the traversal process; assign the result of the sixth formula calculation to the "s4_increment" variable; if the third second-level judgment is no, traverse each anchor unit based on the pointer variable pnt, and assign 0 to the "struct.cable.yield.tension" function and 1 to the "struct.cable.young" function during the traversal process; end the third second-level judgment; end the second first-level judgment.

[0021] As a further description of the above technical solution: The first formula is A = 0.25πD 2 , where A is the cross-sectional area of ​​the anchor rod and D is the diameter of the anchor rod; the second formula is D se =D ss s t , where D se is the tensile displacement of the anchor at the end of the yield stage, D ss is the tensile displacement of the anchor rod at the beginning of the yield stage, s t is the value of the "s2_times" parameter; the third formula is Where y is the dynamic tension, y f is the value of the "yield_force" parameter, s v is the value of the "s3_variable" parameter, s p is the value of the "s3_power" parameter; the fourth formula is s v =s v +s i , where s i is the value of the "s3_interval" parameter; the fifth formula is where t f is the value of the "tensile_failure_force" parameter; c is the value of the "s4_coefficient" parameter; s in is the value of the "s4_increment" parameter; the sixth formula is s in =s in +0.001.

[0022] The present invention provides a calculation method for analyzing the tensile bearing characteristics of anchor rods, which has the following beneficial effects:

[0023] (1) The tensile process of the anchor unit is divided into five stages, namely, the elastic stage, the yield stage, the strengthening stage, the local deformation stage, and the breaking stage. Compared with the original anchor unit calculation method, the present invention takes into account the strengthening stage, the local deformation stage, and the breaking stage, which can better reflect the tensile bearing characteristics of the anchor rod.

[0024] (2) The present invention defines the "yield_force" parameter and the "tensile_failure_force" parameter. The two parameters are the anchor yield force and the anchor tensile limit. Therefore, the present invention distinguishes between the anchor yield force and the anchor tensile limit. This is more consistent with the tensile bearing characteristics of the anchor in the experiment.

[0025] (3) For the strengthening stage, the present invention proposes a third formula and uses it to describe the strain hardening characteristics of the anchor unit. Based on the third formula, after the anchor unit is stretched and enters the strengthening stage, the tension of the anchor unit increases nonlinearly with the increase of tensile displacement to the tensile limit. This is consistent with the strain hardening characteristics of the anchor rod in the experiment.

[0026] (4) For the local deformation stage, the present invention proposes the fifth formula and uses it to describe the strain softening characteristics of the anchor unit. Based on the fifth formula, after the anchor unit is stretched and enters the local deformation stage, the tension of the anchor unit decreases nonlinearly with the increase of the tensile displacement. This is consistent with the strain softening characteristics of the anchor rod in the experiment.

[0027] (5) The present invention defines a breaking stage for the anchor unit. The present invention designs a criterion for determining whether the anchor unit enters the breaking stage after being pulled. Based on the criterion, it can be determined whether the anchor unit has entered the breaking stage after being pulled. If it enters the breaking stage, the anchor unit instantly loses its bearing capacity. Compared with the original anchor unit that cannot consider the breaking behavior of the anchor rod, the present invention can accurately simulate the breaking behavior of the anchor rod after being pulled. This is consistent with the breaking failure behavior of the anchor rod in the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of the present invention, are used to provide a further understanding of the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 The present invention discloses a calculation method for analyzing the tensile bearing characteristics of an anchor rod.

[0030] Figure 2 This is the "modifying" logic structure diagram of the fish function described in the present invention.

[0031] Figure 3 This is the first level judgment logic structure diagram described in the present invention.

[0032] Figure 4 This is the second first-level judgment logic structure diagram of the present invention.

[0033] Figure 5 It is a comparison chart of the calculation results of the present invention, the calculation results of the original anchor unit and the experimental results. DETAILED DESCRIPTION

[0034] like Figures 1 to 4 As shown, the present invention provides a calculation method for analyzing the tensile bearing characteristics of anchor rods, including generating anchor units, defining large deformation calculation modes, defining attribute parameters, defining fish function "initialise", executing fish function "initialise", defining fish function "modifying", and executing fish function "modifying".

[0035] In a specific embodiment: when generating an anchor unit, three parameters, namely, the anchor unit start point, the anchor unit end point, and the number of anchor units, need to be defined, and the number of anchor units is greater than 1.

[0036] In a specific embodiment: when defining the large deformation calculation mode, the large deformation calculation mode is "false".

[0037] In a specific embodiment, the attribute parameters include eleven parameters, including "s2_times", "s3_variable", "s3_power", "s3_interval", "s4_increment", "s4_coefficient", "s5_disp", "recording_flag", "stage_flag", "yield_force", and "tensile_failure_force"; the "s2_times" parameter is the ratio of the tensile displacement at the end of the yield stage of the anchor to the tensile displacement at the beginning of the yield stage; the "s3_variable" parameter, the "s3_power" parameter, and the "s3_interval" parameter are the application parameters, respectively. The "s4_increment" parameter and the "s4_coefficient" parameter are the relative initial value of strain softening and the strain softening contraction coefficient, respectively; the "s5_disp" parameter is the tensile displacement corresponding to the bolt breaking; the "recording_flag" parameter, the "stage_flag" parameter, the "yield_force" parameter and the "tensile_failure_force" parameter are the recording state parameter, the stage state parameter, the anchor yield force and the anchor tensile limit, respectively. The "s4_increment" parameter and the "recording_flag" parameter are both set to 0; the "stage_flag" parameter is set to 1.

[0038] In a specific embodiment: the logical structure of the fish function "initialise" is as follows: based on the pointer variable pnt, each anchor unit is traversed, and the following operations are performed during the traversal process: the "yield_force" parameter is assigned to the "struct.cable.yield.tension" function; the calculation result of the first formula is assigned to the "struct.cable.area" function; the Young's modulus value of the anchor rod is assigned to the "struct.cable.young" function; the bonding stiffness value of the anchoring interface is assigned to the "struct.cable.grout.stiffness" function.

[0039] In a specific embodiment: the logic structure of the fish function "modifying" is as follows: the fish function "modifying" is executed at each time step; the unbalanced force of the tensile end of the anchor unit along the tensile direction is taken out and assigned to the "force" variable, the tensile displacement of the tensile end of the anchor unit along the tensile direction is taken out and assigned to the "disp" variable; the first level judgment process is executed; the second level judgment process is executed.

[0040] In one specific embodiment: the fish function "modifying" is executed at each time step.

[0041] In a specific embodiment: the first level judgment process is to judge whether the "force" variable is greater than or equal to the "yield_force" parameter; if the first level judgment is yes, the first level judgment is carried out, that is, to judge whether the "recording_flag" parameter is zero; if the first level judgment is yes, the "disp" variable is assigned to the "disp_stage2_start" variable, the result of the second formula is assigned to the "disp_stage2_end" variable, 1 is assigned to the "recording_flag" variable, 2 is assigned to the "stage_flag" variable and the first level judgment is ended; the second level judgment is carried out to judge whether the "disp" variable is greater than the "disp_stage2_end" variable. nd" variable. If the second secondary judgment is yes, the third level judgment is carried out, that is, whether the "force" variable is less than the "tensile_failure_force" parameter. If the third level judgment is yes, the fourth level judgment is carried out, that is, whether the "stage_flag" variable is less than 4. If the fourth level judgment is yes, each anchor unit is traversed based on the pointer variable pnt. During the traversal process, the calculation result of the third formula is assigned to the "struct.cable.yield.tension" function; the calculation result of the fourth formula is assigned to the "s3_variable" variable and the fourth level judgment is ended; if the third level judgment is no, 4 is assigned to the "stage_flag" variable and the third level judgment is ended; the second secondary judgment is ended; the first primary judgment is ended.

[0042] In a specific embodiment: the second first-level judgment process is to judge whether the "stage_flag" parameter is equal to 4; if the second first-level judgment is yes, execute the third second-level judgment, that is, judge whether the "disp" variable is less than or equal to the "s5_disp" parameter. If the third second-level judgment is yes, traverse each anchor unit based on the pointer variable pnt, and assign the fifth formula calculation result to the "struct.cable.yield.tension" function during the traversal process; assign the sixth formula calculation result to the "s4_increment" variable; if the third second-level judgment is no, traverse each anchor unit based on the pointer variable pnt, and assign 0 to the "struct.cable.yield.tension" function and 1 to the "struct.cable.young" function during the traversal process; end the third second-level judgment; end the second first-level judgment.

[0043] In a specific embodiment: The first formula is A = 0.25πD 2 , where A is the cross-sectional area of ​​the anchor rod and D is the diameter of the anchor rod; the second formula is D se =D ss s t , where D se is the tensile displacement of the anchor at the end of the yield stage, D ss is the tensile displacement of the anchor rod at the beginning of the yield stage, s t is the value of the "s2_times" parameter; the third formula is Where y is the dynamic tension, y f is the value of the "yield_force" parameter, s v is the value of the "s3_variable" parameter, s p is the value of the "s3_power" parameter; the fourth formula is s v =s v +s i , where s i is the value of the "s3_interval" parameter; the fifth formula is where t f is the value of the "tensile_failure_force" parameter; c is the value of the "s4_coefficient" parameter; s in is the value of the "s4_increment" parameter; the sixth formula is s in =s in +0.001.

[0044] In order to verify the effectiveness of the present invention, the anchor tensile experiment conducted in the paper "Study on Anchoring Characteristics of Anchor Rods under Confining Pressure and Its Influencing Factors" was taken as a case, and the anchor tensile calculation was carried out based on the method proposed in the present invention, and the experimental results were compared with the calculation results of the present invention.

[0045] The paper used a JAW-1500 universal testing machine to conduct a tensile test based on displacement-controlled loading on an anchor rod with a diameter of 20 mm. During the experiment, the anchor rod body was 400 mm long, the clamping sections on both sides were 75 mm long, and the middle experimental section was 250 mm long. The load-tensile displacement curve was recorded during the experiment.

[0046] The experimental process is simulated based on the method proposed in the present invention. Anchor units are generated in FLAC3D and used to simulate anchor rods. The starting point of the anchor unit is the coordinate origin, the end point is (0.25,0,0), and the number of anchor units is 10. The large deformation calculation mode is defined as "false". Attribute parameters are defined, a total of eleven parameters, including "s2_times" is 1.5; "s3_variable" is 10; "s3_power" is 0.35; "s3_interval" is 0.005; "s4_increment" is 0; "s4_coefficient" is 0.12; "s5_disp" is 0.07; "recording_flag" is 0; "stage_flag" is 1; "yield_force" is 179000; "tensile_failure_force" is 243000.

[0047] Define the fish function "initialise". The logic structure of the fish function "initialise" is as follows: traverse each anchor unit based on the pointer variable pnt, and perform the following operations during the traversal process: assign the "yield_force" parameter to the "struct.cable.yield.tension" function; assign the result of the first formula 3.14×10 -4 Assign to the "struct.cable.area" function; set the anchor Young's modulus to 15×10 9 Assign to the "struct.cable.young" function; set the anchor interface bond stiffness to 100×10 6 Assign value to "struct.cable.grout.stiffness" function. Execute fish function "initialise".

[0048] Define fish function "modifying" and execute fish function "modifying".

[0049] The node of the anchor unit is fixed at the origin, and a 1×10 -6 m / s and a constant stretching speed. During the stretching process, the load and stretching displacement at the anchor unit stretching end are recorded. 74,000 time steps are run. Comparison of the load-stretching displacement curve calculated based on the present invention with the load-stretching displacement curve obtained experimentally, such as Figure 5 As shown. In the experiment, the load-tensile displacement curve after the anchor rod is stretched can be divided into five stages in detail: elastic stage, yield stage, strengthening stage, local deformation stage, and breaking stage. The anchor unit proposed in the present invention simulates the anchor rod stretching process and can also obtain five stages: elastic stage, yield stage, strengthening stage, local deformation stage, and breaking stage. This shows that the calculation results of the present invention are consistent with the experimental results. In addition, the yield load and tensile limit obtained by the anchor unit proposed in the present invention after simulating the anchor rod are 179kN and 243kN respectively, which are close to the anchor rod yield load and anchor rod tensile limit obtained in the experiment, proving the effectiveness of the present invention.

[0050] also, Figure 5 The calculation results of the original anchor unit in FLAC3D are shown with a five-pointed star symbol. The original anchor unit calculation results of anchor rod tension only include two stages: elastic stage and yield stage. The load-tension displacement curve obtained by the original anchor unit simulating the anchor rod tension process is significantly different from the experimental curve. Therefore, the original anchor unit cannot accurately reflect the tensile performance of the anchor rod. Compared with the original anchor unit calculation, the calculation method proposed in the present invention has obvious advantages.

Claims

1. A calculation method for analyzing the tensile bearing characteristics of anchor bolts, characterized in that: It includes generating anchor units, defining large deformation calculation mode, defining attribute parameters, defining fish function "initialise", executing fish function "initialise", defining fish function "modifying", and executing fish function "modifying".

2. A calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: When generating an anchor unit, three parameters need to be defined: the anchor unit start point, the anchor unit end point, and the number of anchor units, and the number of anchor units must be greater than 1.

3. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: When defining the large deformation calculation mode, the large deformation calculation mode is "false".

4. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: The attribute parameters include eleven parameters, including "s2_times", "s3_variable", "s3_power", "s3_interval", "s4_increment", "s4_coefficient", "s5_disp", "recording_flag", "stage_flag", "yield_force", and "tensile_failure_force". The "s2_times" parameter is the ratio of the tensile displacement at the end of the yield stage of the anchor to the tensile displacement at the beginning of the yield stage. The "s3_variable" parameter, the "s3_power" parameter, and the "s3_interval" parameter are the strain hardening basis "s4_increment" and "s4_coefficient" are the relative initial value of strain softening and the strain softening contraction coefficient, respectively; "s5_disp" is the tensile displacement corresponding to the bolt breaking; "recording_flag", "stage_flag", "yield_force" and "tensile_failure_force" are the recording state parameter, stage state parameter, bolt yield force and bolt tensile limit, respectively; "s4_increment" and "recording_flag" are both set to 0; "stage_flag" is set to 1.

5. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: The logical structure of the fish function "initialise" is as follows: based on the pointer variable pnt, it traverses each anchor unit and performs the following operations during the traversal process: assigns the "yield_force" parameter to the "struct.cable.yield.tension" function; assigns the calculation result of the first formula to the "struct.cable.area" function; assigns the value of the Young's modulus of the anchor rod to the "struct.cable.young" function; assigns the value of the bonding stiffness of the anchor interface to the "struct.cable.grout.stiffness" function.

6. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: The logical structure of the fish function "modifying" is as follows: the fish function "modifying" is executed at each time step; the unbalanced force at the tensile end of the anchor unit along the tensile direction is taken out and assigned to the "force" variable, and the tensile displacement at the tensile end of the anchor unit along the tensile direction is taken out and assigned to the "disp" variable; the first level judgment process is executed; the second level judgment process is executed.

7. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: The fish function "modifying" is executed at each time step.

8. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: The first level judgment process is to judge whether the "force" variable is greater than or equal to the "yield_force" parameter; if the first level judgment is yes, the first level judgment is carried out, that is, to judge whether the "recording_flag" parameter is zero; if the first level judgment is yes, the "disp" variable is assigned to the "disp_stage2_start" variable, the result of the second formula is assigned to the "disp_stage2_end" variable, 1 is assigned to the "recording_flag" variable, 2 is assigned to the "stage_flag" variable and the first level judgment is ended; the second level judgment is carried out to judge whether the "disp" variable is greater than the "disp_stage2_end" variable If the second secondary judgment is yes, the third level judgment is carried out, that is, whether the "force" variable is less than the "tensile_failure_force" parameter is judged. If the third level judgment is yes, the fourth level judgment is carried out, that is, whether the "stage_flag" variable is less than 4. If the fourth level judgment is yes, each anchor unit is traversed based on the pointer variable pnt, and the result of the third formula calculation is assigned to the "struct.cable.yield.tension" function during the traversal process; the result of the fourth formula calculation is assigned to the "s3_variable" variable and the fourth level judgment is ended; if the third level judgment is no, 4 is assigned to the "stage_flag" variable and the third level judgment is ended; the second secondary judgment is ended; the first primary judgment is ended.

9. The calculation method for analyzing the tensile bearing characteristics of anchor rods according to claim 1, characterized in that: The second first-level judgment process is to judge whether the "stage_flag" parameter is equal to 4; if the second first-level judgment is yes, execute the third second-level judgment, that is, judge whether the "disp" variable is less than or equal to the "s5_disp" parameter. If the third second-level judgment is yes, traverse each anchor unit based on the pointer variable pnt, and assign the fifth formula calculation result to the "struct.cable.yield.tension" function during the traversal process; assign the sixth formula calculation result to the "s4_increment" variable; if the third second-level judgment is no, traverse each anchor unit based on the pointer variable pnt, and assign 0 to the "struct.cable.yield.tension" function and 1 to the "struct.cable.young" function during the traversal process; end the third second-level judgment; end the second first-level judgment.

10. A calculation method for analyzing the tensile bearing characteristics of an anchor rod according to claim 1, characterized in that: The first formula is A = 0.25πD 2 , where A is the cross-sectional area of ​​the anchor rod and D is the diameter of the anchor rod; the second formula is D se =D ss s t , where D se is the tensile displacement of the anchor at the end of the yield stage, D ss is the tensile displacement of the anchor rod at the beginning of the yield stage, s t is the value of the "s2_times" parameter; the third formula is Where y is the dynamic tension, y f is the value of the "yield_force" parameter, s v is the value of the "s3_variable" parameter, s p is the value of the "s3_power" parameter; the fourth formula is s v =s v +s i , where s i is the value of the "s3_interval" parameter; the fifth formula is where t f is the value of the "tensile_failure_force" parameter; c is the value of the "s4_coefficient" parameter; s in is the value of the "s4_increment" parameter; the sixth formula is s in =s in +0.001.

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