A method for simulating failure of an anchor based on shear strain

Abstract

The application relates to a shear strain-based anchor rod failure simulation method. The method comprises the following steps: establishing a pile structure unit in numerical simulation software; monitoring the displacement of each node in a local coordinate system along a y direction and a z direction and the length of each element structure component in the pile structure unit by using a FISH function; calculating shear strain according to the displacement along the y direction and the z direction and the length of the element structure component; judging whether the shear strain is within a plastic shear strain and a limit shear strain range, if yes, setting the plastic bending moment of the unit as the measured bending moment of the unit when the shear strain is equal to the plastic shear strain; finally, judging whether the shear strain exceeds the limit shear strain, if yes, setting the plastic bending moment and the limit tensile strain of the unit as positive values which tend to 0. The stress stage of the anchor rod can be adjusted according to the shear strain size.

Description

Technical Field

[0001] This application relates to the field of engineering structure simulation technology, and in particular to a method for simulating anchor bolt failure based on shear strain. Background Technology

[0002] FLAC3D numerical simulation software can perform 3D modeling and finite difference calculations on on-site construction and indoor test objects. Its built-in pile structural elements can simulate anchor bolts and their interaction with the surrounding rock, such as... Figure 1 As shown, the pile structural unit consists of nodes and element structural components connecting the nodes, and the force is transferred between them through tangential springs, normal springs, and sliders. Therefore, by adjusting the various physical and mechanical parameters of the pile structural unit, the axial tension and normal shear of the anchor can be achieved. A limit tensile strain is also set in the pile structural unit to achieve tensile failure. However, in actual engineering, anchors often fail due to shear displacement at the structural surface, and the pile structural unit does not perform shear failure. Under transverse shear, the shear stress of the pile structural unit increases indefinitely, which is clearly inconsistent with reality. Current methods use the FISH function built into FLAC3D software to correct the pile structural unit, judging whether shear failure has occurred by monitoring whether the shear force of the pile structural unit exceeds the set shear limit value. Shear failure can be replaced by the breakage of the pile structural unit. However, the current method controls the shear failure of the anchor through the shear limit value and cannot effectively control the shear displacement of the pile structural unit.

[0003] Therefore, there is an urgent need in related technologies for a method that can accurately set the shear displacement or shear strain when the anchor bolt yields and fails. Summary of the Invention

[0004] Therefore, it is necessary to provide a method for simulating anchor failure based on shear strain, which can accurately set the shear displacement or shear strain when the anchor bolt yields and fails, in order to address the above-mentioned technical problems.

[0005] Firstly, this application provides a method for simulating anchor bolt failure based on shear strain. The method includes: In numerical simulation software, pile structural elements are created, and the nodes and element structural components of the pile structural elements are numbered. The FISH function is used to monitor the displacement of each node in the local coordinate system along the y and z directions, as well as the length of each element structural member in the pile structural unit; The shear strain is calculated based on the displacements along the y and z directions and the length of the element structural member. Determine whether the shear strain is within the range of plastic shear strain and ultimate shear strain. If so, set the plastic bending moment of the unit to the measured bending moment of the unit when the shear strain equals the plastic shear strain. Determine whether the shear strain exceeds the ultimate shear strain. If so, set the plastic bending moment and ultimate tensile strain of the unit to positive values ​​that tend to be 0.

[0006] Optionally, in one embodiment of this application, the step of using the FISH function to monitor the displacement of each node along the y and z directions in the local coordinate system and the length of each element structural member in the pile structural unit includes: Traverse the nodes according to their node numbers and calculate the displacement of each node in the local coordinate system along the y and z directions. The element structural components are traversed according to their component numbers, and the initial length of each element structural component when it is not under stress is calculated.

[0007] Optionally, in one embodiment of this application, the formula for calculating the shear strain is:

[0008] in, Represents shear strain. and They represent the first The point and the first The displacement of a point along the x-direction in the local coordinate system and They represent the first The point and the first The displacement of a point along the y-direction in the local coordinate system This represents the initial length of the element structural member when it is not under stress.

[0009] Optionally, in one embodiment of this application, the formula for calculating the measured bending moment is:

[0010] in, This represents the bending moment of the element structural member along the y-direction. This represents the bending moment of the element structural member along the z-direction.

[0011] Optionally, in one embodiment of this application, the plastic bending moment and ultimate tensile strain can be set to 1×10⁻⁶. -10At this point, the element structural member will fail, and the shear force and axial force will become 0.

[0012] The above-described anchor failure simulation method based on shear strain first establishes a pile structural element in numerical simulation software and numbers the nodes and element structural members of the pile structural element. Then, the FISH function is used to monitor the displacement of each node along the y and z directions in the local coordinate system, as well as the length of each element structural member in the pile structural element. Next, the shear strain is calculated based on the displacement along the y and z directions and the length of the element structural member. Then, it is determined whether the shear strain is within the range of plastic shear strain and ultimate shear strain. If so, the plastic bending moment of the element is set to the measured bending moment of the element when the shear strain equals the plastic shear strain. Finally, it is determined whether the shear strain exceeds the ultimate shear strain. If so, the plastic bending moment and ultimate tensile strain of the element are set to positive values ​​approaching 0. By monitoring the displacement of the nodes at both ends of each element structural member in the local coordinate system along the y and z directions and the length of the element structural member, the shear strain is calculated, thus allowing adjustment of the stress stage of the anchor bolt based on the magnitude of the shear strain. Yielding of the pile structural element was achieved by setting the plastic bending moment to the measured bending moment when the shear strain equals the plastic shear strain. During the yielding stage, the shear force and axial force remain constant, while the displacement continues to increase. Shear failure of the pile structural element was achieved by setting the plastic bending moment and ultimate tensile strain to positive values ​​approaching zero when the shear strain reaches the ultimate shear strain. At shear failure, the axial force and shear force of the anchor bolt decrease to zero. The magnitude of the shear displacement at the yield shear strain and ultimate shear strain can be controlled by setting these values. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a pile structure unit in one embodiment; Figure 2 This is a flowchart illustrating an anchor bolt failure simulation method based on shear strain in one embodiment. Figure 3 This is a schematic diagram of the shear mechanics model of a pile structural unit in one embodiment; Figure 4 This is a schematic diagram of a numerical simulation model of anchor bolt shear in one embodiment; Figure 5 The image shows the anchor bolt shear force-shear displacement curve when the plastic shear strain is 0.1 and the ultimate shear strain is 0.4 in one embodiment. Figure 6The image shows the anchor bolt shear force-shear displacement curve when the plastic shear strain is 0.1 and the ultimate shear strain is 0.2 in one embodiment. Figure 7 The image shows the anchor bolt shear force-shear displacement curve when the plastic shear strain is 0.2 and the ultimate shear strain is 0.4 in one embodiment. Figure 8 This is a schematic diagram of the shape of the anchor bolt during the yielding and failure stages in one embodiment. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0015] In one embodiment, such as Figure 2 As shown, a method for simulating anchor bolt failure based on shear strain is provided, including the following steps: S101: In FLAC3D software, create a pile structural unit with n nodes, where the node numbers are 1 to n, and the element structural component numbers are 1 to n-1.

[0016] S102: The FISH function is used to monitor the displacement of each node in the local coordinate system along the y and z directions, as well as the length of each element structural member in the pile structural unit.

[0017] S103: Calculate the shear strain based on the displacements of the nodes at both ends of each element structural member along the y and z directions and the length of the element structural member.

[0018] S104: Determine whether the shear strain of the element structural member is within the range of plastic shear strain and ultimate shear strain. If the condition is met, then set the plastic bending moment of the element to the measured bending moment of the element when the shear strain is equal to the plastic shear strain.

[0019] S105: Determine whether the shear strain of the element structural member exceeds the ultimate shear strain. If the condition is met, set the plastic bending moment and ultimate tensile strain of the element to positive values ​​that tend to 0.

[0020] In one embodiment of this application, the step of using the FISH function to monitor the displacement of each node in the local coordinate system along the y and z directions, as well as the length of each element structural member in the pile structural unit, includes: S201: Traverse the nodes from number 1 to n in sequence according to the node number, and calculate the displacement of each node in the local coordinate system along the y and z directions.

[0021] S202: Based on the element structural component number, traverse the element structural components from number 1 to n~1 in sequence, and calculate the initial length of each element structural component when it is not under stress.

[0022] In one embodiment of this application, the formula for calculating the shear strain is:

[0023] in, Represents shear strain. and They represent the first The point and the first The displacement of a point along the x-direction in the local coordinate system and They represent the first The point and the first The displacement of a point along the y-direction in the local coordinate system This represents the initial length of the element structural member when it is not under stress.

[0024] In one embodiment of this application, the plastic bending moment can be assigned a value through the function struct.pile.moment.plastic(pointer, moment), where pointer represents the element structural member pointer, which can be obtained through the function struct.find(i), and moment represents the plastic bending moment value to be assigned.

[0025] In one embodiment of this application, the formula for calculating the measured bending moment is:

[0026] in, This represents the bending moment of the element structural member along the y-direction. This represents the bending moment of the element structural member along the z-direction.

[0027] In one embodiment of this application, the plastic bending moment and ultimate tensile strain can be set to 1×10⁻⁶. -10 At this point, the element structural member will fail, and the shear force and axial force will become 0.

[0028] In one embodiment of this application, the shear mechanics model of the pile structural unit written using the FISH function is as follows: Figure 3 As shown, in this mechanical model, the pile structural element undergoes three stages—elasticity, yielding, and failure—in sequence as the shear strain increases. Its mechanical expression is as follows:

[0029] in, The shear force acting on the anchor bolt. For anchor bolt shear modulus, Let the cross-sectional area of ​​the anchor bolt be... For the shear strain of the anchor bolt, This represents the plastic shear strain of the anchor bolt. This represents the ultimate shear strain of the anchor bolt.

[0030] In one embodiment of this application, a shearing simulation is performed using a pile structure element written with the FISH function, and the established numerical model is as follows: Figure 4 As shown, the model dimensions are 30mm (length) × 30mm (width) × 60mm (height), and it consists of 1024 elements and 1377 nodes. Zone elements are used to simulate the surrounding rock, interface structural elements to simulate the shear structure, and pile structural elements to simulate the anchor bolts. The parameter values ​​for each part are shown in Tables 1-3. The pile structural elements are divided into 25 segments, with nodes numbered 1-26 from bottom to top, and the element structural components are numbered 1-25.

[0031] Table 1 Anchor Bolt Parameters

[0032] Table 2 Surrounding Rock Parameters

[0033] Table 3 Structural Surface Parameters

[0034] A horizontal shear velocity of 1×10⁻⁶ m / s was applied to the upper zone element, while normal displacement constraints were applied to the bottom and sides of the lower zone element. Simultaneously, different plastic shear strains and ultimate shear strains were applied to the pile structural element. The shear force of structural member number 13 near the structural plane and the shear displacement of node number 14 in the pile structural element were monitored. The resulting curves are shown below. Figures 5-7 As shown, by setting different plastic shear strains and ultimate shear strains, it is possible to control the anchor bolt to have different shear force-shear displacement curves, and the curves sequentially go through three stages: elastic, plastic, and failure. The deformation of the anchor bolt in the plastic and failure stages is as follows: Figure 8As shown, during the plastic stage, the anchor bolt undergoes significant shear deformation at the structural surface, with some elastic bending occurring at its upper and lower parts, which is consistent with the actual shear deformation of the anchor bolt. During the failure stage, the shear deformation of the anchor bolt at the structural surface continues to increase, and the shear force drops to zero, achieving shear failure of the anchor bolt. In this embodiment, by adjusting the plastic shear strain and the ultimate shear strain, the shear displacement of the anchor bolt at each stage can be controlled, thus achieving shear strain-controlled anchor bolt yielding and failure processes.

[0035] In the above-mentioned anchor failure simulation method based on shear strain, firstly, a pile structural element is established in numerical simulation software, and the nodes and element structural members of the pile structural element are numbered; then, the FISH function is used to monitor the displacement of each node along the y and z directions in the local coordinate system, as well as the length of each element structural member in the pile structural element; then, the shear strain is calculated based on the displacement along the y and z directions and the length of the element structural member; then, it is determined whether the shear strain is within the range of plastic shear strain and ultimate shear strain. If so, the plastic bending moment of the element is set to the measured bending moment of the element when the shear strain equals the plastic shear strain; finally, it is determined whether the shear strain exceeds the ultimate shear strain. If so, the plastic bending moment and ultimate tensile strain of the element are set to positive values ​​approaching 0. By monitoring the displacement of the nodes at both ends of each element structural member in the pile structural element along the y and z directions in the local coordinate system, as well as the length of the element structural member, the shear strain is calculated, thereby enabling the adjustment of the stress stage of the anchor bolt according to the magnitude of the shear strain. Yielding of the pile structural element was achieved by setting the plastic bending moment to the measured bending moment when the shear strain equals the plastic shear strain. During the yielding stage, the shear force and axial force remain constant, while the displacement continues to increase. Shear failure of the pile structural element was achieved by setting the plastic bending moment and ultimate tensile strain to positive values ​​approaching zero when the shear strain reaches the ultimate shear strain. At shear failure, the axial force and shear force of the anchor bolt decrease to zero. The magnitude of the shear displacement at the yield shear strain and ultimate shear strain can be controlled by setting these values.

[0036] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0037] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0038] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for simulating anchor bolt failure based on shear strain, characterized in that, The method includes: In numerical simulation software, pile structural elements are created, and the nodes and element structural components of the pile structural elements are numbered. The FISH function is used to monitor the displacement of each node in the local coordinate system along the y and z directions, as well as the length of each element structural member in the pile structural unit; The shear strain is calculated based on the displacements along the y and z directions and the length of the element structural member. Determine whether the shear strain is within the range of plastic shear strain and ultimate shear strain. If so, set the plastic bending moment of the unit to the measured bending moment of the unit when the shear strain equals the plastic shear strain. Determine whether the shear strain exceeds the ultimate shear strain. If so, set the plastic bending moment and ultimate tensile strain of the unit to positive values ​​that tend to 0. The formula for calculating the shear strain is: in, Represents shear strain. and They represent the first The point and the first The displacement of a point along the x-direction in the local coordinate system and They represent the first The point and the first The displacement of a point along the y-direction in the local coordinate system This represents the initial length of the element structural member when it is not under stress. The formula for calculating the measured bending moment is: in, This represents the bending moment of the element structural member along the y-direction. This represents the bending moment of the element structural member along the z-direction.

2. The anchor bolt failure simulation method based on shear strain according to claim 1, characterized in that, The method of using the FISH function to monitor the displacement of each node in the local coordinate system along the y and z directions, as well as the length of each element structural member in the pile structural unit, includes: Traverse the nodes according to their node numbers and calculate the displacement of each node in the local coordinate system along the y and z directions. The element structural components are traversed according to their component numbers, and the initial length of each element structural component when it is not under stress is calculated.

3. The anchor bolt failure simulation method based on shear strain according to claim 1, characterized in that, The plastic bending moment and ultimate tensile strain can be set to 1×10. -10 At this point, the element structural member will fail, and the shear force and axial force will become 0.

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