Ancient seawall structure safety assessment method and system based on nonlinear bonding units

Abstract

The invention discloses an ancient seawall structure safety assessment method and system based on nonlinear bonding units, and belongs to the technical field of seawall operation and maintenance protection. In the prior art, the interaction between strip stone bodies of a seawall and the interaction of a soil body structure are not considered, so that the internal structure state of the ancient seawall is difficult to accurately master, and the safety analysis cannot be performed on the structure of the ancient seawall. According to the ancient seawall structure safety assessment method based on the nonlinear bonding units, a seawall grid generation model, a seawall boundary search model, a seawall attribute simulation model, a seawall deformation simulation model and a seawall safety assessment model are constructed, and the bonding units capable of simulating interaction between a seawall body and a soil body and between the seawall body and a strip stone body are established; according to the method, safety evaluation of the seawall structure can be realized, so that the method can fully consider the interaction between the stone strip bodies and the interaction of the soil body structure of the seawall, so that the internal structure state of the ancient seawall can be accurately mastered, and operation and maintenance personnel can be helped to carry out ancient seawall protection more comprehensively and flexibly.

Description

Technical Field

[0001] The present invention relates to a method and system for evaluating the structural safety of ancient seawalls based on non-linear bonding units, belonging to the technical field of seawall operation and maintenance protection. Background Art

[0002] To resist the pounding of tides and the increasingly severe erosion of river water recently, reinforcement projects have been carried out on many seawall sections, and a series of means have also been adopted to strengthen the monitoring of the deformation of the ancient seawall body. Although the reinforcement project aims to protect the ancient seawall, the construction machinery, load, disturbance, etc. during the construction process all affect the structural safety of the ancient seawall. At the same time, weather changes and wave action are also posing challenges to the ancient seawall that has experienced hundreds of years.

[0003] Furthermore, Chinese Patent Application (Publication No. CN110779570A) discloses a safety monitoring and early warning system for the construction period of ancient seawall reinforcement, including monitoring equipment, data acquisition equipment, a monitoring management cloud platform, alarm equipment, and a terminal. The monitoring equipment and data acquisition equipment are connected by cables or wireless networks, and the monitoring management cloud platform is respectively connected to the data acquisition equipment, alarm equipment, and terminal. The monitoring equipment includes deformation monitoring equipment, seepage monitoring equipment, pressure monitoring equipment, environmental quantity monitoring equipment, vibration monitoring equipment, and video monitoring equipment, and is connected to the data acquisition equipment by cables or wireless networks. For the construction period of ancient seawall reinforcement, advanced technologies such as new sensors, the Internet of Things, and cloud computing are used to monitor, analyze, and give early warnings on the deformation, seepage, environmental quantity, vibration conditions, etc. during the construction period of ancient seawall reinforcement, ensuring the real-time nature of safety monitoring and strengthening the safety control during the construction period of ancient seawall reinforcement.

[0004] However, the above scheme is mainly used for the safety monitoring during the construction period of ancient seawall reinforcement, without considering the interaction between the stone blocks of the seawall and the interaction of the soil structure, resulting in difficulty in accurately grasping the internal structural state of the ancient seawall. Therefore, it is impossible to conduct a safety analysis of the ancient seawall structure, which is not conducive to the protection of the ancient seawall.

[0005] The information disclosed in this background art is only used to understand the background of the inventive concept of the present invention, and therefore it may include information that does not constitute prior art. Summary of the Invention

[0006] In view of the above problems or one of the above problems, one object of the present invention is to provide a method and system for safety assessment of ancient seawall structures based on non-linear bonding elements. By constructing a seawall grid generation model, a seawall boundary search model, a seawall property simulation model, a seawall deformation simulation model, and a seawall safety assessment model, boundary grids that can represent the interface between the seawall body and the soil body and the connection between the stone blocks are obtained. Based on the non-linear constitutive algorithm, the boundary grids are given the properties of non-linear elements to form bonding elements. Then, an elastoplastic algorithm is used for simulation calculation to obtain the structural deformation data of the seawall, realizing the safety assessment of the seawall structure. Therefore, the interaction between the stone blocks of the seawall and the interaction of the soil structure can be fully considered, so that the internal structural state of the ancient seawall can be accurately grasped, which is beneficial to the protection of the seawall structure.

[0007] In view of the above problems or one of the above problems, another object of the present invention is to provide a method and system for safety assessment of ancient seawall structures based on non-linear bonding elements. By establishing bonding elements that can simulate the interaction between the seawall body and the soil body and the stone blocks, the deformation data of the interface between the seawall body and the soil body and the stone blocks can be quickly output, which is convenient for quickly identifying dangerous situations in combination with relevant specifications, improving the dimension of seawall structure safety analysis, and helping operation and maintenance personnel to carry out the protection of ancient seawalls more comprehensively and flexibly.

[0008] To achieve one of the above objects, the first technical solution of the present invention is as follows: A method for safety assessment of ancient seawall structures based on non-linear bonding elements, comprising the following steps: Step 1, process the cross-sectional structure information of a certain seawall through a pre-constructed seawall grid generation model to obtain a seawall simulation grid; Step 2, use a pre-constructed seawall boundary search model to process the seawall simulation grid to obtain boundary grids for representing the interface between the seawall body and the soil body and the connection between the stone blocks; Step 3, adopt a pre-constructed seawall property simulation model, and based on the non-linear constitutive algorithm, endow the boundary grids with the properties of non-linear elements to form bonding elements; Step 4, use a pre-constructed seawall deformation simulation model, apply loads to the bonding elements, and perform simulation calculations using an elastoplastic algorithm to obtain the structural deformation data of the seawall; Step 5, based on a pre-constructed seawall safety assessment model, analyze the structural deformation data of the seawall to obtain the safety assessment information of the seawall structure, and complete the safety assessment of the ancient seawall structure based on non-linear bonding elements.

[0009] The present invention constructs a seawall grid generation model, a seawall boundary search model, a seawall property simulation model, a seawall deformation simulation model, and a seawall safety assessment model to obtain boundary grids that can represent the interface between the seawall body and the soil body and the connection between the stone blocks. Based on the non-linear constitutive algorithm, the boundary grids are given the properties of non-linear elements to form bonding elements. Then, an elastoplastic algorithm is used for simulation calculation to obtain the structural deformation data of the seawall, realizing the safety assessment of the seawall structure. Therefore, the present invention can fully consider the interaction between the stone blocks of the seawall and the interaction of the soil structure, so as to accurately grasp the internal structure state of the ancient seawall and facilitate the protection of the seawall structure.

[0010] Furthermore, by establishing bonding elements that can simulate the interaction between the seawall body and the soil body and the stone blocks, the present invention can effectively improve the accuracy and speed of the contact calculation between the stone blocks on the back and bottom of the seawall and the surrounding soil of the seawall, and effectively solve the convergence problem of the model algorithm when facing complex contact surfaces such as stone block dislocation.

[0011] At the same time, through the above simulation model, the present invention can quickly output the deformation data of the interface between the seawall body and the soil body and the stone blocks, which is convenient for quickly identifying dangerous situations in combination with relevant specifications, further improving the dimension of the seawall structure safety analysis, and helping the operation and maintenance personnel to carry out the protection of the ancient seawall more comprehensively and flexibly.

[0012] As a preferred technical measure: Step 1, process the cross-section structure information of a certain seawall through the previously constructed seawall grid generation model to obtain the seawall simulation grid as follows: Obtain the cross-section structure information of a certain seawall in the current operation stage; According to the cross-section structure information of a certain seawall, determine the actual cross-section structure data, which includes the backfill behind the seawall, the stratified soil body of the seawall foundation, the stone blocks, the seawall body, and the front support row piles of the seawall; Model the backfill behind the seawall, the stratified soil body of the seawall foundation, and the front support row piles of the seawall as the soil part uniformly, and consider the action range and boundary effect influence of the surcharge load, water pressure load, and self-weight load of the seawall body to obtain the geometric simulation object of the soil body; Model the stone blocks as the seawall body part uniformly, and consider the horizontal wave surge action. Stratify the stone blocks in the horizontal direction to obtain the geometric simulation object of the seawall body; Perform grid division on the geometric simulation object of the soil body and the geometric simulation object of the seawall body respectively, and locally encrypt the grids close to the seawall body part to obtain the soil part grids and the seawall body part grids; Merge the nodes of the soil part grids and the seawall body part grids according to their spatial positions to obtain the complete seawall simulation grid.

[0013] As a preferred technical measure: Step 2: Use the previously constructed seawall boundary search model to process the seawall simulation grid. The method to obtain the boundary grid is as follows: Obtaining a seawall simulation grid, which includes a soil grid and a pond grid; Based on the soil body partial grid and the pond body partial grid, the grid nodes on the interface between the soil body and the pond body are obtained, and a soil body node group and a pond body node group are formed; the soil body node group and the pond body node group have the same geometric position and one-to-one correspondence, and belong to the soil body partial grid and the pond body partial grid respectively; According to the partial grid of the pond body, at the interface where two stone strips contact each other, select the upper node group at the bottom of the previous stone strip and the lower node group at the top of the next stone strip; the geometric positions of the upper node group and the lower node group are the same and correspond one to one; The soil node group, pond node group, upper node group and lower node group are aggregated to obtain the boundary grid.

[0014] As the preferred technical measures: Step 3: Using the previously constructed seawall property simulation model, based on the nonlinear constitutive algorithm, the boundary grid is given the properties of nonlinear units to form bonding units as follows: Obtaining a boundary grid, which includes a soil node group, a pond node group, an upper node group, and a lower node group; According to the node order in the soil node group and the pond node group, quadrilateral elements with zero thickness are sequentially established as the first mesh element group at the interface between the pond and the soil; Based on the nonlinear constitutive algorithm, the first grid unit group is given the attribute of the nonlinear unit, so that the first grid unit has elastic-plastic deformation ability, thereby obtaining the first bonding unit group for simulating the contact between the pond body and the soil body; According to the node sequence in the upper node group and the lower node group, quadrilateral units with zero thickness are sequentially established as the second grid unit group of the interface of the stone body; Based on the nonlinear constitutive algorithm, the second grid unit group is given the attribute of the nonlinear unit, so that the second grid unit has damage characteristics, thereby obtaining the second bonding unit group for simulating the bonding effect between the stone bodies; The first grid unit group and the second bonding unit group are coupled to obtain a bonding unit.

[0015] As the preferred technical measures: Based on the nonlinear constitutive algorithm, the method of assigning the attributes of the nonlinear unit to the first mesh unit group so that the first mesh unit has elastic-plastic deformation ability is as follows: From the geological survey data of the seawall section, the physical and mechanical parameters of each layer of the seawall foundation and the backfill behind the seawall are obtained; Based on physical and mechanical parameters, the Mohr-Coulomb yield criterion is established to calculate the tangential elastoplastic deformation, so as to characterize the bonding effect between the pond body and the soil mass and the tensile stress characteristics; According to the Mohr-Coulomb yield criterion, model parameters are set, which include normal stiffness, tangential stiffness, interface adhesion, friction coefficient of the interface, and isotropic hardening parameter; the hardening parameter is used to adjust the tangent slope in the sliding stage; Based on the elastic part and the plastic part, the interface tangential displacement is calculated; Based on the elastic part and the tangential stiffness, the interface shear stress is calculated; Based on the normal stiffness and the interface normal displacement, the interface normal stress is calculated Based on the interface shear stress, interface normal stress, friction coefficient of the interface, interface adhesion, isotropic hardening parameter, and cumulative tangential displacement, the flow criterion value is calculated; When the flow criterion value is less than zero for the interface tangential behavior, the first grid element is in the elastic stage, and the plastic part of the tangential displacement remains unchanged; when the flow criterion value is equal to zero for the interface tangential displacement, the plastic part of the first grid element begins to accumulate, and the plastic displacement increment on the yield surface follows the Mohr-Coulomb yield criterion; According to the flow criterion value, the contact surface of the first grid element group is given the attributes of a nonlinear element, so that the first grid element has the ability of elastoplastic deformation, and the simulation of the contact and frictional interaction process of the first grid element group is realized.

[0016] Furthermore, the physical and mechanical parameters include soil density, Young's modulus, Poisson's ratio, cohesion, and internal friction angle; from the construction data of the supporting row piles, the density, elastic modulus, and Poisson's ratio of the front-pond supporting row piles are obtained; Generally, the soil layer is divided into three types, which are the pond base soil mass, the first layer of soil mass behind the pond, and the second layer of soil mass behind the pond; The depth of the first layer of soil mass behind the pond is 0 - 1.73 meters, and the depth of the second layer of soil mass behind the pond is 1.73 - 5.5 meters.

[0017] As an optimal technical measure: Based on the nonlinear constitutive algorithm, the second grid element group is given the attributes of a nonlinear element, so that the second grid element has damage characteristics. The method for obtaining the second bonding element group is as follows: From the data of the pond body materials of the seawall, the data of the bonded structure of the stone blocks are obtained; The data of the bonded structure of the stone blocks at least include interface pressure, density, elastic modulus, and Poisson's ratio; Based on the data of the bonded structure of the stone blocks, a stress-strain curve of the stone blocks is generated to characterize the strength of the glutinous rice mortar bonding the stone blocks; According to the stress-strain curve of the stone blocks, the interface tangential stiffness, normal stiffness, and the ultimate interface tensile strength are determined; Based on the normal stiffness and softening slope, establish the variation relationship between the normal stress of the constitutive interface and the normal displacement of the interface. Based on the interface shear stiffness, the ultimate tensile strength of the interface, and the control parameter, establish the variation relationships of the interface shear stress, the interface shear displacement, and the interface normal displacement, that is, the normal cracking and shear stiffness relationship. According to the variation relationship between the normal stress of the constitutive interface and the normal displacement of the interface, and the normal cracking-shear stiffness relationship, endow the second grid element group with the attributes of nonlinear elements to simulate the bonding effect between the block stones, so that the second grid element has damage characteristics, and thus obtain the second bonding element group.

[0018] As a preferred technical measure: The variation relationship between the normal stress of the constitutive interface and the normal displacement of the interface includes the following content: When the interface normal displacement exceeds the critical damage displacement, damage begins to occur in the interface normal direction; when the interface normal displacement reaches the fracture limit value, the interface normal fractures. With the evolution of the interface normal damage, the critical damage displacement gradually evolves from the initial displacement value to the normal fracture threshold. The evolution of the interface normal stress is divided into four stages, which include the normal elastic behavior under the interface compression state, the normal elastic behavior under the interface normal opening state, the normal damage behavior under the interface normal opening state, and the stage of complete shear failure of the interface. Or / and, the normal cracking and shear stiffness relationship includes the following content: By adjusting the control parameter, different normal cracking and shear stiffness relationships are constructed; when the control parameter is equal to zero and the normal displacement is greater than zero, the shear stiffness of the interface immediately drops to zero; when the control parameter is equal to two, the shear stiffness of the interface is independent of the interface normal displacement and remains constant. The evolution of the interface shear stress is divided into three stages, which include the shear elastic behavior under the interface compression state, the shear elastic behavior under the interface normal opening state, and the stage of complete shear failure of the interface.

[0019] The present invention establishes a bonding unit for simulating the interaction between block stones, establishes a connection between the tangential interaction of the block stone interface and the normal cracking, simulates the weakening of the shear stiffness of the seawall block stone interface under the action of load, and improves the simulation accuracy of the model under lateral forces such as waves and earth pressure behind the seawall.

[0020] As a preferred technical measure: Step 4, use the previously constructed seawall deformation simulation model, apply the load to the bonding unit, and use the elastoplastic algorithm for simulation calculation. The method for obtaining the structural deformation data of the seawall is as follows: Obtain the loads on the seawall, including hydrostatic pressure, wave force, and the backfill load behind the seawall; Set the displacement boundary conditions, including the vertical restricted displacement at the bottom and the horizontal restricted displacements on both sides; Apply the loads and the displacement boundary conditions to the bonding elements, conduct a simulation analysis, and obtain the maximum displacement of the seawall body and the maximum shear stress between the stone blocks; Couple the maximum displacement of the seawall body and the maximum shear stress between the stone blocks to obtain the structural deformation data of the seawall.

[0021] To achieve one of the above purposes, the second technical solution of the present invention is as follows: A method for evaluating the structural safety of an ancient seawall based on non-linear bonding elements, including the following: Through a pre-constructed seawall grid generation model, according to the latest drawing of the cross-section of the ancient seawall, draw the geometric models of the stone blocks, the soil behind the seawall, and the soil at the bottom of the seawall, divide the finite element grid to obtain the seawall grid and the soil grid; then merge the nodes of the seawall grid and the soil grid, and set the parameters of each layer of soil, each level of stone blocks, and the bonding material according to the survey and test data to obtain the seawall simulation grid; Adopt a pre-constructed seawall property simulation model, and based on the seawall simulation grid, obtain the bonding elements between the seawall body and the soil and the bonding elements between the stone blocks; Use a pre-constructed seawall deformation simulation model, apply the loads to the bonding elements, and conduct a simulation calculation using the elastoplastic algorithm to obtain the structural deformation data of the seawall; then analyze the structural deformation data of the seawall to obtain the safety evaluation information of the seawall structure, and complete the safety evaluation of the ancient seawall structure based on non-linear bonding elements.

[0022] The present invention fully considers the typical failure modes of ancient seawalls caused by mortar weakening. By establishing a seawall grid generation model, a seawall property simulation model, and a seawall deformation simulation model, and outputting the deformation data of each interface of the ancient seawall, it can help the operation and maintenance personnel quickly lock the weak layers under specific working conditions and protect the ancient seawall from a more subtle level. And through the use of bonding elements, the accuracy of the analysis results of the ancient seawall is further improved, the dimension of the structural safety analysis of the ancient seawall is enhanced, and it helps the operation and maintenance personnel to carry out the protection of the ancient seawall more comprehensively and flexibly.

[0023] Furthermore, the method for obtaining the bonding elements between the seawall body and the soil and the bonding elements between the stone blocks based on the seawall simulation grid by using a pre-constructed seawall property simulation model is as follows: Based on the seawall simulation grid, copy the grid nodes on the interface between the seawall grid and the soil grid to form two sets of node groups with the same geometric positions and one-to-one correspondence, which respectively belong to the seawall grid and the soil grid, obtaining independent seawall grid part and soil grid part. Then, form degenerate interface grids in sequence by four corresponding upper and lower nodes, endow the interface grid between the seawall and the soil with the attributes of non-linear elements, and form the bonding elements between the seawall and the soil; Based on the seawall simulation grid, copy the unit nodes on the bonding interface between the stone blocks to form two sets of unit node groups with the same geometric positions and one-to-one correspondence, which respectively belong to the stone blocks of two ancient seawalls; and form degenerate unit grids according to the unit node groups, and then endow the unit grids between the stone blocks with the attributes of non-linear elements to form the bonding elements between the stone blocks.

[0024] To achieve one of the above purposes, the third technical solution of the present invention is: An ancient seawall structure safety assessment system based on non-linear bonding elements, which includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned ancient seawall structure safety assessment method based on non-linear bonding elements.

[0025] Compared with the prior art solutions, the present invention has the following beneficial effects: The present invention constructs a seawall grid generation model, a seawall boundary search model, a seawall attribute simulation model, a seawall deformation simulation model, and a seawall safety assessment model to obtain boundary grids that can represent the boundaries between the seawall and the soil and the connections between the stone blocks, and based on the non-linear constitutive algorithm, endow the boundary grids with the attributes of non-linear elements to form bonding elements; then use the elastoplastic algorithm for simulation calculation to obtain the structural deformation data of the seawall and realize the safety assessment of the seawall structure. Therefore, the present invention can fully consider the interactions between the stone blocks of the seawall and the soil structure, so as to accurately grasp the internal structure state of the ancient seawall and facilitate the protection of the seawall structure.

[0026] Furthermore, the present invention can effectively improve the accuracy and speed of the contact calculation between the stone blocks on the back and bottom of the seawall and the surrounding soil of the seawall by establishing bonding elements that can simulate the interactions between the seawall and the soil and the stone blocks, and effectively solve the convergence problem of the model algorithm when facing complex contact surfaces such as stone block dislocation.

[0027] Meanwhile, through the above simulation model, the present invention can quickly output the deformation data of the interfaces between the pond body, the soil body, and the strip stone body, facilitating the rapid identification of dangerous situations in combination with relevant specifications, further enhancing the dimension of the safety analysis of the seawall structure, and helping the operation and maintenance personnel to carry out the protection of the ancient seawall more comprehensively and flexibly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is a schematic flow chart for the safety analysis of the pond body structure of the present invention; Figure 2 FIG. is a schematic structural diagram of an adhesive unit of the present invention; Figure 3 FIG. is a schematic structural diagram of a grid structure of the present invention; Figure 4 FIG. is a schematic structural diagram of an adhesive unit between the pond body and the soil body of the present invention; Figure 5 FIG. is a distribution nephogram of a displacement of the present invention; Figure 6 FIG. is a distribution nephogram of a shear stress of the pond body of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] On the contrary, the present invention covers any alternatives, modifications, equivalent methods and solutions made within the spirit and scope of the present invention as defined by the claims. Further, in order to enable the public to better understand the present invention, some specific details are described in detail in the following detailed description of the present invention. Those skilled in the art can fully understand the present invention without the description of these details.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0032] As Figure 1 shown, the first specific embodiment of the method for evaluating the safety of an ancient seawall structure based on a non-linear adhesive unit of the present invention: The method for evaluating the safety of an ancient seawall structure based on a non-linear adhesive unit includes the following steps: Step 1, process the cross-section structure information of a certain seawall through a pre-constructed seawall grid generation model to obtain a seawall simulation grid; Step 2: Using the pre-constructed seawall boundary search model, process the seawall simulation grid to obtain the boundary grid, which is used to characterize the connection between the seawall body and the soil body and the connection between the stone blocks. Step 3: Adopt the pre-constructed seawall property simulation model. Based on the non-linear constitutive algorithm, endow the boundary grid with the properties of non-linear elements to form bonding elements. Step 4: Use the pre-constructed seawall deformation simulation model, apply the load to the bonding elements, and perform simulation calculations using the elastic-plastic algorithm to obtain the structural deformation data of the seawall. Step 5: Based on the pre-constructed seawall safety assessment model, analyze the structural deformation data of the seawall to obtain the safety assessment information of the seawall structure, and complete the safety assessment of the ancient seawall structure based on non-linear bonding elements.

[0033] The second specific embodiment of the method for safety assessment of ancient seawall structure based on non-linear bonding elements of the present invention: The method for safety assessment of ancient seawall structure based on non-linear bonding elements includes the following steps: Step 1: Through the pre-constructed seawall grid generation model, according to the latest drawing of the cross-section of the ancient seawall, draw the geometric models of the stone seawall body, the soil body behind the seawall and the soil body at the bottom of the seawall, divide the finite element grid, obtain the seawall body grid and the soil body grid and merge the nodes. At this time, the grid is a single-node grid. Define the parameters of each layer of soil body, each level of stone blocks and the bonding material according to the survey and test data for subsequent finite element calculations.

[0034] Step 2: Adopt the pre-constructed seawall property simulation model, copy the grid nodes on the interface between the seawall body grid and the soil body grid to form two groups of node groups with the same geometric positions and corresponding one by one, which respectively belong to the seawall body grid and the soil body grid, forming independent seawall body grid part and soil body grid part. At this time, there are double nodes in the grid. Then, the degenerate interface grid is formed by four nodes corresponding up and down in sequence. Endow the interface grid between the seawall body and the soil body with the properties of non-linear elements to form the bonding elements between the seawall body and the soil body.

[0035] Step 3: Adopt the pre-constructed seawall property simulation model, copy the unit nodes on the bonding interface between the stone blocks, and perform the same operation as in Step 2 to form a series of degenerate interface grids. Endow the interface grid between the seawall body and the soil body with the properties of non-linear elements to form the bonding elements between the stone blocks.

[0036] Step 4: Based on the pre-constructed seawall deformation simulation model, apply the load to the bonding elements to obtain the relative sliding (cracking), displacement and inclination of the seawall body and the soil body, which are used for the safety evaluation of the seawall body structure of the ancient seawall.

[0037] Based on non - linear bonding units, this invention analyzes the safety state of the ancient seawall structure by considering the influence of normal damage between the contact surfaces of the stone blocks on the tangential stiffness of the bonding material and the frictional contact between the seawall body and the soil body. Furthermore, this invention improves the accuracy of the safety analysis of the ancient seawall structure, enhances the accuracy of the local structure safety analysis of the seawall, and at the same time, the seawall analysis model of this invention has good robustness and can achieve rapid iterative calculation, which is applicable to the structural safety analysis of the ancient seawall under construction and extreme working conditions. Further, the non - linear bonding unit proposed by this invention has good compatibility with the static and dynamic finite - element calculation models, and can realize multi - working - condition analysis under the same model.

[0038] In step one of this embodiment, it specifically includes the following steps: First step, obtain the cross - section structure information of the ancient seawall at the current operation stage from the latest reinforcement drawings of the ancient seawall, select key monitoring cross - sections, and draw a two - dimensional plane geometric model including the main structures affecting the safety analysis of the ancient seawall, such as the backfill behind the seawall, the layered soil body of the seawall foundation, the stone seawall body, and the front - support row piles of the seawall. When performing geometric modeling, the soil body of the seawall foundation, the soil body behind the seawall, and the front - support row piles of the seawall are drawn uniformly as the soil part, and the stone seawall body is drawn uniformly as the seawall part.

[0039] Comprehensively consider the action range and boundary - effect influence of loads such as surcharge, water pressure, and the self - weight of the seawall body. Since the main loading condition of the seawall part is the horizontal surge action, in the modeling, the stone body can be modeled by horizontal layering for appropriate simplification. On this basis, divide the soil - part model and the seawall - part model respectively to obtain quadrilateral meshes, and locally refine the meshes near the seawall part. After merging the nodes of the soil - part meshes and the seawall - part meshes according to their spatial positions, the complete finite - element mesh model of the ancient - seawall cross - section can be obtained. When merging nodes, it is necessary to ensure that the number of nodes at the contact between the seawall - part mesh and the soil - part mesh is the same and aligned.

[0040] Second step, obtain the physical and mechanical parameters of each layer of the soil body of the seawall foundation and the backfill behind the seawall from the geological exploration report of the ancient - seawall cross - section, including soil density, Young's modulus, Poisson's ratio, cohesion, and internal friction angle; obtain the density, elastic modulus, and Poisson's ratio of the stone body and the front - support row piles of the seawall from the seawall - body material report and the construction report of the support row piles of the ancient seawall, and define the strength of the glutinous - rice mortar bonding the stone bodies under different pressures.

[0041] In step two of this embodiment, it specifically includes the following steps: First step, copy the grid nodes on the interface between the pond body and the soil body grid to form two sets of node groups with the same geometric positions and one-to-one correspondence, which belong to the pond body grid and the soil body grid respectively, forming independent pond body grid part and soil body grid part. On the interface where the pond body grid and the soil body grid are in contact, select node group 1 on the contact edge of the pond body grid and node group 2 on the contact edge of the soil body grid. According to the node order in node group 1 and node group 2, establish quadrilateral elements (with zero thickness) in sequence as the bonding element group of the pond body and the soil body interface. As Figure 2 shown, node group 1 contains nodes A, B, C, D; node group 2 contains nodes a, b, c, d, and then quadrilateral element 1 (nodes A, B, b, a), quadrilateral element 2 (nodes B, C, c, b) and quadrilateral element 3 (nodes C, D, d, c) can be established.

[0042] Second step, endow the bonding element group of the pond body and the soil body interface with a non-linear constitutive model to simulate the contact action between the pond body and the soil body. This constitutive model realizes the simulation of the contact-friction interaction process by introducing elastoplastic deformation in the tangential direction of the contact surface. Compared with the traditional contact algorithm, it does not need to consider complex contact settings such as the position of the master and slave contact surfaces, the grid density, and the relative slip degree, avoiding complex contact surface search and iterative calculations, and has good robustness.

[0043] The main principle of this constitutive model is that when the normal compressive stress on the contact surface is large, the frictional force between the two contact surfaces is stronger, and the contact interface is less likely to enter the slip stage where the relative displacement develops rapidly, because Coulomb's friction law only depends on one parameter . It realizes the boundary condition criterion of non-invasion of the contact boundary by establishing the relationship between the tangential and normal stresses in the local area during the slip stage. The relationship between the tangential stress and the normal stress is as follows:

[0044] where is the interface shear stress, is the interface normal stress, is the friction coefficient of the interface.

[0045] In order to express the above criterion with a formula, it is necessary to assume that the mechanical behavior of the contact surface follows the elastic law, and the same is true for the slope of the sliding direction change in the tangential behavior criterion. At the same time, in order to simplify the description of the sliding between the pond body and the soil body, considering that there is a certain bonding effect between the pond body and the soil body in contact with it, the interface can withstand a certain degree of tensile stress. Based on the above two points, this constitutive model uses the Mohr-Coulomb yield criterion to control the development of tangential elastoplastic deformation.

[0046] The flow rule of the tangential deformation of this model is the interface and the sliding cone shear plane Orthogonal, the normal behavior of the interface always remains elastic and does not introduce plastic characteristics. The calculation formula for the maximum tensile strength of the interface is as follows:

[0047] Where, is the interface bonding force, is the maximum tensile strength of the interface.

[0048] This model depends on the following four parameters: normal stiffness , tangential stiffness , interface bonding force , interface friction coefficient , and an isotropic hardening parameter is introduced, and its role is to adjust the tangent slope during the sliding stage. The tangential displacement of the model can be decomposed into an elastic part and a plastic part . The mechanical formulas involved in this model are as follows:

[0049]

[0050]

[0051]

[0052]

[0053]

[0054] Where, is the deformation characterization function, is the stress, is the interface tangential displacement, is the interface shear stress, is the interface normal stress, is the interface normal displacement, is the cumulative tangential displacement, is the tangential displacement increment, is the isotropic hardening modulus.

[0055] When , the interface tangential behavior is in the elastic stage, and the plastic part of the tangential displacement remains unchanged. When , the plastic part of the interface tangential displacement begins to accumulate, and the plastic displacement increment on the yield surface obeys the flow criterion shown in the above formula.

[0056] In the third step of this embodiment, the following steps are specifically included: In the first step, on the interface where the block stones are in contact, select node group 1 at the bottom of the upper block stone and node group 2 at the top of the lower block stone. According to the node order in node group 1 and node group 2, successively establish quadrilateral elements (with zero thickness) as the interface bonding element group of the block stones. Similar to the first step in step two, as Figure 2 shown, node group 1 includes nodes A, B, C, D, and node group 2 includes nodes a, b, c, d. Then, quadrilateral element 1 (nodes A, B, b, a), quadrilateral element 2 (nodes B, C, c, b), and quadrilateral element 3 (nodes C, D, d, c) can be established.

[0057] In the second step, endow the interface bonding element group between the block stones with a non - linear constitutive model to simulate the bonding effect between the block stones. This constitutive model introduces damage behavior in the normal direction of the interface. When the normal displacement of the interface exceeds the critical damage displacement, that is, when the interface stress reaches the ultimate tensile stress after that, damage begins to occur in the normal direction of the interface. The calculation formula of the critical damage displacement is as follows:

[0058] When the normal displacement reaches the fracture limit, the interface fractures in the normal direction. The calculation formula of the fracture limit is as follows:

[0059] Among them, is the softening damage parameter, is the fracture limit value.

[0060] The normal stress of this constitutive model at the interface and the normal displacement of the interface satisfy the following relationship:

[0061] Among them, is the relationship formula between the normal stress at the interface and the normal displacement of the interface.

[0062] Among them is the initial normal stiffness of the interface. In the initial tensile opening stage, the normal direction of the interface shows linear elastic behavior. When , the normal direction of the interface enters the softening stage, and the normal stiffness gradually decreases. The softening slope is . With the evolution of the normal damage of the interface, the critical damage displacement gradually evolves from the initial towards the normal fracture threshold . The evolution of the normal stress at the interface is divided into four stages: (1) Normal elastic behavior under interface compression state, normal contact threshold The larger the value, the smaller the compressive mutual penetration value in the normal direction of the interface; (2) Normal elastic behavior under the normal opening state of the interface; (3) Normal damage (softening) behavior under the normal opening state of the interface; (4) The stage of complete tangential rupture of the interface, and its tangential stiffness is controlled by the normal displacement of the interface.

[0063] The constitutive interface tangential stress , interface tangential displacement and interface normal displacement satisfy the following relationship:

[0064]

[0065] Among them, is the relationship formula of the interface tangential stress , interface tangential displacement and interface normal displacement .

[0066] Among them represents the initial tangential stiffness of the interface, represents the offset of the balance point of tangential slip when the interface opens normally, The value of is the interface at when final value; is the tangential fracture threshold, control parameter .

[0067] Therefore, by adjusting the control parameter , different normal cracking and tangential stiffness relationships can be constructed. When and the normal displacement is greater than zero, the tangential stiffness of the interface immediately drops to zero; when , the tangential stiffness of the interface is independent of the normal displacement of the interface and remains constant all the time. In the present invention, set . The evolution of the interface tangential stress is divided into three stages: (1) Tangential elastic behavior under the interface compression state, (2) Tangential elastic behavior under the normal opening state of the interface, (3) The stage of complete tangential rupture of the interface.

[0068] In the fourth step of this embodiment, it specifically includes the following steps: The first step is to endow each part of the cross-section grid of the ancient seawall with the material and constitutive properties of the bonding unit of the pond body and the soil body, and the bonding unit of the stone slab interface. The Mohr-Coulomb model is selected for the soil part, and the elastic model is selected for the pond body and the front retaining row piles of the pond. The specific material model parameter values are taken from the second step of the first step. The normal stiffness is selected for the pond-soil interface bonding unit , tangential stiffness , interfacial bonding force , friction coefficient of the interface Four constitutive parameters; for the stone interface bonding element, the initial normal stiffness of the contact surface is selected , initial tangential stiffness of the contact surface , contact threshold of the contact surface , softening damage parameter , initial normal tensile strength of the contact surface Five constitutive parameters, and the specific values of the constitutive model parameters are taken from the second step of the first step.

[0069] Second step, set the displacement boundary conditions for the finite element model of the ancient seawall section. The vertical displacement at the bottom of the model is restricted, i.e., DY = 0, and the horizontal displacement on both sides of the model is restricted, i.e., DX = 0. The ancient seawall is mainly subjected to static loads such as the surcharge behind the seawall, wave force, and hydrostatic pressure. During the actual execution process, the magnitudes and acting positions of various loads can be confirmed according to specific working conditions.

[0070] Third step, conduct a structural safety analysis of the ancient seawall. Process the calculation results of the finite element model of the ancient seawall section to obtain the horizontal displacement and vertical displacement of each node of the seawall body. The inclination of the seawall body can be calculated from the horizontal and vertical displacements of each node. The crack width between the seawall and the soil can be obtained from the output results of the soil-seawall interface bonding element, and the normal stress and shear stress of the interface can be obtained from the output results of the stone seawall body interface bonding element. Combining the analysis results of the finite element model, according to the relevant structural safety codes of the ancient seawall, comprehensively judge the structural safety of the ancient seawall section based on the horizontal displacement of the seawall body, the crack width between the seawall and the soil, and the interlayer shear stress.

[0071] Therefore, the present invention can enhance the accuracy and speed of the contact calculation between the stone bodies at the back and bottom of the ancient seawall and the surrounding soil of the seawall by establishing a non-linear bonding element that simulates the interaction between the seawall body, the soil body, and the stone bodies, and effectively avoids the convergence problem of the traditional contact algorithm in the face of complex contact surfaces such as stone dislocation. At the same time, the element can quickly output the crack development of the interfaces between the seawall body, the soil body, and the stone bodies, which is convenient for quickly identifying dangerous situations in combination with relevant codes.

[0072] Furthermore, by establishing a non-linear bonding element that simulates the interaction between the stone blocks, the tangential interaction between the stone interfaces is related to the normal cracking, and the weakening of the tangential stiffness of the ancient seawall stone interfaces caused by cracking under the action of loads is simulated, improving the simulation accuracy of the model under lateral forces such as waves and earth pressure behind the seawall. At the same time, the damage caused by the weakening of the mortar is a typical failure mode of the ancient seawall. The non-linear interface bonding element can directly output the shear stress and normal stress of each layer interface of the ancient seawall, which can help the operation and maintenance personnel quickly lock the weak layers under specific working conditions and protect the ancient seawall at a more subtle level.

[0073] In addition, the nonlinear bonding element has good compatibility with common elastic and elastoplastic materials, as well as dynamic and static solution methods. The use of the nonlinear bonding element further improves the accuracy of the analysis results of the ancient seawall finite element model. Combining the stress, cracking and other output results of the nonlinear bonding element further enhances the dimension of the structural safety analysis of the ancient seawall, helping the operation and maintenance personnel to carry out the protection of the ancient seawall more comprehensively and flexibly.

[0074] A specific embodiment of applying the present invention to evaluate the structural safety of a certain ancient seawall: A certain ancient seawall is a fish-scale stone seawall, and its structure can be divided into the seawall body, the seawall foundation, the toe apron structure, the soil body behind the seawall and the foundation soil body. The seawall body is made of strip stones laid in a zigzag pattern. Its height is 5.44 m, the bottom width is 3.48 m, and it tapers from the bottom to the top to a top width of 1.44 m. The cross-section of the strip stone is 32 cm × 38.4 cm and there are 17 layers in total. According to the ancient seawall analysis method based on nonlinear bonding elements proposed by the present invention, analyze the deformation and stress of the cross-section of the ancient seawall under static loads such as post-seawall surcharge, wave force, and hydrostatic pressure, and evaluate the state of the ancient seawall; specifically, it includes the following steps: Step 1: According to the latest drawings of the cross-section of the ancient seawall, draw the geometric models of the strip stone seawall body, the soil body behind the seawall and the soil body at the bottom of the seawall, divide and merge the finite element mesh nodes of each part into an overall mesh, and define the parameters of each layer of soil, each level of strip stones and the bonding material according to the survey and test data for subsequent finite element calculations.

[0075] Step 2: Copy the mesh nodes on the interface between the seawall body and the soil body mesh to form two sets of node groups with the same geometric positions and one-to-one correspondence, which belong to the seawall body mesh and the soil body mesh respectively, forming independent seawall body mesh parts and soil body mesh parts, and forming degenerate interface meshes in sequence by four corresponding nodes from top to bottom. Endow the boundary mesh between the seawall body and the soil body with the attributes of nonlinear elements to form the bonding elements between the seawall body and the soil body.

[0076] Step 3: Copy the unit nodes on the bonding interface between the strip stones, and perform the same operations as in Step 2 to form a series of degenerate interface meshes, endow the boundary mesh between the seawall body and the soil body with the attributes of nonlinear elements, and form the bonding elements between the strip stone bodies.

[0077] Step 4: Adopt the Mohr-Coulomb elastoplastic model of the soil body, set the boundary conditions and load conditions, carry out the structural safety analysis of the ancient seawall, and obtain the interlayer stress between the strip stone bodies, the relative sliding (cracking) between the seawall body and the soil body, the displacement and inclination of the seawall body for the structural safety evaluation of the seawall body of the ancient seawall.

[0078] In Step 1 of this embodiment, it specifically includes the following steps: Step 1: Obtain the cross-sectional structure information of the ancient seawall at the current operation stage from the latest reinforcement drawings of the ancient seawall, select key monitoring cross-sections, and draw a two-dimensional plane geometric model that includes the main structures affecting the safety analysis of the ancient seawall, such as the backfill behind the seawall, the layered soil mass of the seawall foundation, the stone seawall body, and the front retaining row piles of the seawall. When performing geometric modeling, the soil mass of the seawall foundation, the soil mass behind the seawall, and the front retaining row piles of the seawall are drawn together as the soil part, and the stone seawall body is drawn together as the seawall body part.

[0079] Taking into account the action range and boundary effect influence of loads such as surcharge, water pressure, and the self-weight of the seawall body, the recommended geometric modeling size of the soil part is . Since the main loading condition of the seawall body part is the horizontal wave surge action, in the modeling, the stone body can be modeled by horizontal stratification and appropriately simplified. On this basis, structured quadrilateral meshes are respectively divided for the seawall body part model and the soil part model. The meshes near the seawall body part can be locally refined. After merging the nodes of the soil part mesh and the seawall body part mesh according to their spatial positions, the complete finite element mesh model of the ancient seawall cross-section can be obtained. As shown in Figure 3 , this mesh model has a total of 13,307 nodes, 1,352 one-dimensional line elements, and 12,994 two-dimensional quadrilateral surface elements, and first-order elements are used for mesh division. After mesh independence verification and trial calculation, it is proved that this mesh meets the finite element simulation calculation requirements of Step 2.

[0080] Step 2: Obtain the physical and mechanical parameters of each layer of soil mass of the seawall foundation and the backfill behind the seawall from the geological exploration report of the ancient seawall cross-section, including soil density, Young's modulus, Poisson's ratio, cohesion, and internal friction angle; obtain the density, elastic modulus, and Poisson's ratio of the stone body and the front retaining row piles of the seawall from the seawall body material report and the retaining row pile construction report of the ancient seawall.

[0081] According to the relevant reports, the soil layers are divided into three types, namely the soil mass of the seawall foundation, the soil mass behind the seawall with a depth of 0 - 1.73 meters, and the soil mass behind the seawall with a depth of 1.73 - 5.5 meters. The Mohr-Coulomb model is used for the soil mass, and the linear elastic model is used for the stone body and the front retaining row piles of the seawall. The specific parameters are shown in Table 1.

[0082] Table 1: Material Parameter Table of Ancient Seawall

[0083] For the strength of the glutinous rice mortar bonding the stone body, it can be calculated by the following formula:

[0084] In the formula is the interface pressure of the stone body, is the interface strain, is the interfacial stress. By plotting the stress-strain curve, the slope of the rising segment of the curve is the tangential and normal stiffness of the interface, and the stress extreme value of the curve is the ultimate tensile strength of the interface.

[0085] In the second step of this embodiment, it specifically includes the following steps: The first step is to copy the grid nodes on the interface between the pond body and the soil body grid to form two sets of node groups with the same geometric position and one-to-one correspondence, which respectively belong to the pond body grid and the soil body grid, forming independent pond body grid parts and soil body grid parts. On the interface where the pond body grid and the soil body grid are in contact, select node group 1 on the contact edge of the pond body grid and node group 2 on the contact edge of the soil body grid. According to the node order in node group 1 and node group 2, sequentially establish quadrilateral elements (with zero thickness) as the bonding unit group of the pond body and the soil body interface. For example, if node group 1 includes nodes A, B, C, D and node group 2 includes nodes a, b, c, d, quadrilateral element 1 (nodes A, B, b, a), quadrilateral element 2 (nodes B, C, c, b), and quadrilateral element 3 (nodes C, D, d, c) can be established.

[0086] According to the above method, establish a unit with a thickness of 0 between the pond body and the soil body, and the generation position and results of this unit are as Figure 3 shown.

[0087] The second step is to endow the bonding unit group of the pond body and the soil body interface with a non-linear constitutive model to simulate the contact action between the pond body and the soil body. This constitutive model realizes the simulation of the contact-friction interaction process by introducing elastoplastic deformation in the tangential direction of the contact surface. Compared with the traditional contact algorithm, it does not need to consider complex contact settings such as the position of the master-slave contact surface, the density of the grid, and the relative slip degree, avoiding complex contact surface search and iterative calculations, and has good robustness.

[0088] The main principle of this constitutive model is that when the normal compressive stress on the contact surface is large, the friction between the two contact surfaces is stronger, and the contact interface is less likely to enter the slip stage where the relative displacement develops rapidly, because Coulomb's friction law only depends on one parameter . It realizes the boundary condition criterion of non-intrusion of the contact boundary by establishing the relationship between the tangential and normal stresses in the local area during the slip stage. In order to express the above criterion with formulas, it is necessary to assume that the mechanical behavior of the contact surface follows the elastic law, and the same is true for the slope of the change in the sliding direction in the tangential behavior criterion. At the same time, in order to simplify the description of the sliding between the stone body and the soil body, considering that there is a certain bonding effect between the stone pond body and the soil body in contact with it, the interface can withstand a certain degree of tensile stress. Based on the above two points, this constitutive model uses the Mohr-Coulomb yield criterion to control the development of tangential elastoplastic deformation.

[0089] This model depends on the following four parameters: normal stiffness , tangential stiffness , interfacial adhesion , coefficient of friction at the interface , and an isotropic hardening parameter is introduced , which functions to adjust the tangent slope during the sliding stage. The tangential displacement of the model can be decomposed into an elastic part and a plastic part , and the mechanical formulas involved in this model are as follows:

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] where is the tangential displacement at the interface, is the tangential stress at the interface, is the normal stress at the interface, is the normal displacement at the interface, is the cumulative tangential displacement, is the increment of tangential displacement, is the isotropic hardening modulus.

[0096] When the tangential behavior at the interface is in the elastic stage, and the plastic part of the tangential displacement remains unchanged. When the plastic part of the tangential displacement at the interface begins to accumulate, and the plastic displacement increment on the yield surface obeys the flow criterion shown in the above formula.

[0097] In this example, the constitutive parameters of the model used are shown in Table 2 below: Table 2: Constitutive Parameter Table of the Model

[0098] In step three of this embodiment, the following steps are specifically included: First step, on the interface where the block stones are in contact, select node group 1 at the bottom of the upper block stone and node group 2 at the top of the lower block stone. According to the node order in node group 1 and node group 2, establish quadrilateral elements (with zero thickness) in sequence as the interface bonding element group of the block stones. For example, if node group 1 contains nodes A, B, C, D and node group 2 contains nodes a, b, c, d, then quadrilateral element 1 (nodes A, B, b, a), quadrilateral element 2 (nodes B, C, c, b), and quadrilateral element 3 (nodes C, D, d, c) can be established.

[0099] According to the above method, establish elements with a thickness of 0 between the block stones. The position where this element is generated is as Figure 4 shown in the yellow part.

[0100] Second step, endow the interface bonding element group of the block stone pond with a non-linear constitutive model to simulate the bonding effect between the block stones. This constitutive model introduces damage behavior in the interface normal direction. When the interface normal displacement exceeds the critical damage displacement, that is, when the interface stress reaches the ultimate tensile stress after that, damage begins to occur in the interface normal direction. When the normal displacement reaches the fracture limit, the interface normal direction fractures.

[0101] The interface normal stress and the interface normal displacement satisfy the following relationship:

[0102] where is the initial interface normal stiffness. In the initial tensile opening stage, the interface normal direction shows linear elastic behavior. When , the interface normal direction enters the softening stage, and the normal stiffness gradually decreases. The softening slope is .

[0103] The interface shear stress , the interface shear displacement and the interface normal displacement satisfy the following relationship:

[0104] where represents the initial interface shear stiffness, represents the offset of the equilibrium point of shear slip when the interface normal direction opens, The value of at is the final value. is the shear fracture threshold, and the parameter .

[0105] According to the calculation formula in the second step of Step 1, the mortar material parameters between the stone blocks at each layer from top to bottom can be obtained, and the specific values are shown in Table 3.

[0106] Table 3: Mortar Material Parameter Table for Stone Blocks

[0107] In the fourth step of this embodiment, it specifically includes the following steps: The first step is to assign material and constitutive properties to each part of the cross-section grid of the ancient seawall with the pond soil interface bonding unit and the stone block interface bonding unit. The Mohr-Coulomb model is selected for the soil part, and the elastic model is selected for the seawall body and the front seawall support row piles. The specific material model parameter values are taken from the second step of Step 1. The normal stiffness , tangential stiffness , interface adhesion , and friction coefficient of the interface are selected as the four constitutive parameters for the pond soil interface bonding unit; the initial normal stiffness of the contact surface , initial tangential stiffness of the contact surface , contact threshold of the contact surface , softening damage parameter , and initial normal tensile strength of the contact surface are selected as the five constitutive parameters for the stone block interface bonding unit. The specific constitutive model parameter values are taken from the second step of Step 1.

[0108] The second step is to set displacement boundary conditions for the finite element model of the ancient seawall cross-section. The vertical displacement at the bottom of the model is restricted, i.e., DY = 0, and the horizontal displacement on both sides of the model is restricted, i.e., DX = 0. In this case, the ancient seawall is mainly subjected to hydrostatic pressure, wave force, backfill load behind the seawall, etc., and the specific values are shown in Table 4: Table 4: Ancient Seawall Load Table

[0109] The third step is to carry out the structural safety analysis of the ancient seawall, process the calculation results of the finite element model of the ancient seawall cross-section, and obtain relevant results of the seawall body such as Figure 5 , Figure 6 and as shown in Table 5.

[0110] Table 5: Results of Pond Body Simulation Analysis Using the Present Invention

[0111] For the same case, a certain commercial software is used for calculation under the same settings, and the calculation results are shown in Table 6.

[0112] Table 6: Results of Pond Body Simulation Analysis Using a Certain Commercial Software

[0113] By comparing the data in Table 5 with the data in Table 6, it can be seen that the calculation results of applying the present invention are similar to those of a certain commercial software, indicating that the method proposed by the present invention is accurate and reliable.

[0114] Therefore, by using the method for analyzing the safety of the body structure of ancient seawalls based on non-linear bonding units proposed by the present invention, it is possible to accurately evaluate and analyze the relevant behaviors of ancient seawalls, enabling relevant departments to timely understand the operating status of ancient seawalls and assisting in making operation and maintenance decisions.

[0115] An equipment embodiment of applying the method of the present invention: An electronic device, which includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned method for evaluating the safety of the structure of ancient seawalls based on non-linear bonding units.

[0116] A computer medium embodiment of applying the method of the present invention: A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the above-mentioned method for evaluating the safety of the structure of ancient seawalls based on non-linear bonding units.

[0117] Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, and computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program code.

[0118] The present application is described according to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products of the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes or / and blocks Figure 1 one block or multiple blocks.

[0119] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in the process Figure 1 one process or multiple processes or / and blocks Figure 1 or multiple blocks.

[0120] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in the process Figure 1 one process or multiple processes or / and blocks Figure 1 or multiple blocks.

[0121] The model in this application is an object that constitutes an objective descriptive morphological structure by means of an entity or a virtual representation. The object is not equal to an object and is not limited to entities and virtuals. It can be a data processing function, a software program, a processing mode, a usage method, an operation method, a workflow, an application process, electronic hardware, a circuit module, a processing system, a system imitation, or a simulation object.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for safety assessment of ancient seawall structures based on non - linear bonding elements, characterized in that: It includes the following steps: Step 1, through a pre - constructed seawall grid generation model, process the structural information of a certain seawall section to obtain a seawall simulation grid; Step 2, use a pre - constructed seawall boundary search model to process the seawall simulation grid to obtain a boundary grid, which is used to characterize the connection between the seawall body and the soil body and the connection between stone blocks; Step 3, adopt a pre - constructed seawall property simulation model, based on a non - linear constitutive algorithm, endow the boundary grid with the properties of non - linear elements to form bonding elements; Step 4, use a pre - constructed seawall deformation simulation model, apply loads to the bonding elements, and perform simulation calculations using an elastoplastic algorithm to obtain the structural deformation data of the seawall; Step 5, based on a pre - constructed seawall safety assessment model, analyze the structural deformation data of the seawall to obtain the safety assessment information of the seawall structure, and complete the safety assessment of the ancient seawall structure based on non - linear bonding elements.

2. The method for safety assessment of ancient seawall structures based on non - linear bonding elements according to claim 1, characterized in that: In Step 1, the method for processing the structural information of a certain seawall section through a pre - constructed seawall grid generation model to obtain a seawall simulation grid is as follows: Obtain the structural information of a certain seawall section at the current operation stage; According to the structural information of a certain seawall section, determine the actual structural data of the section, which includes the backfill behind the seawall, the stratified soil body of the seawall foundation, stone blocks, the seawall body, and the front support sheet piles of the seawall; Unify the modeling of the backfill behind the seawall, the stratified soil body of the seawall foundation, and the front support sheet piles of the seawall as the soil part, and consider the action range and boundary effect influence of the surcharge load, water pressure load, and self - weight load of the seawall body to obtain a geometric simulation object of the soil body; Unify the modeling of the stone block body as the seawall body part, and consider the horizontal surge action. Layer the stone block body in the horizontal direction to obtain a geometric simulation object of the seawall body; Perform grid division on the geometric simulation object of the soil body and the geometric simulation object of the seawall body respectively, and locally encrypt the grids near the seawall body part to obtain the soil part grid and the seawall body part grid; Merge the nodes of the soil part grid and the seawall body part grid according to their spatial positions to obtain a complete seawall simulation grid.

3. The method for safety assessment of ancient seawall structures based on non - linear bonding elements according to claim 1, characterized in that: In Step 2, the method for processing the seawall simulation grid using a pre - constructed seawall boundary search model to obtain a boundary grid is as follows: Obtain the seawall simulation grid, which includes the soil part grid and the seawall body part grid; Based on the soil part grid and the seawall body part grid, obtain the grid nodes on the interface between the soil body and the seawall body, and form a soil node group and a seawall body node group; the geometric positions of the soil node group and the seawall body node group are the same and correspond one by one, and they belong to the soil part grid and the seawall body part grid respectively; According to the seawall body part grid, on the interface where two stone block bodies are in contact, select the upper node group at the bottom of the upper stone block body and the lower node group at the top of the lower stone block body; the geometric positions of the upper node group and the lower node group are the same and correspond one by one; Summarize the soil node group, pond node group, upper node group, and lower node group to obtain a boundary grid.

4. The method for evaluating the structural safety of an ancient seawall based on non-linear bonding elements as claimed in claim 1, wherein: Step 3: Using the previously constructed seawall property simulation model, based on the non-linear constitutive algorithm, endow the boundary grid with the properties of non-linear elements to form bonding elements, and the method is as follows: Obtain the boundary grid, which includes a soil node group, a pond node group, an upper node group, and a lower node group; According to the node order in the soil node group and the pond node group, sequentially establish quadrilateral elements with zero thickness as the first grid element group at the interface between the pond and the soil; Based on the non-linear constitutive algorithm, endow the first grid element group with the properties of non-linear elements, so that the first grid element has the ability of elastoplastic deformation, and thus obtain the first bonding element group for simulating the contact effect between the pond and the soil; According to the node order in the upper node group and the lower node group, sequentially establish quadrilateral elements with zero thickness as the second grid element group at the interface of the stone blocks; Based on the non-linear constitutive algorithm, endow the second grid element group with the properties of non-linear elements, so that the second grid element has damage characteristics, and thus obtain the second bonding element group for simulating the bonding effect between the stone blocks; Couple the first grid element group and the second bonding element group to obtain bonding elements.

5. The method for evaluating the structural safety of an ancient seawall based on non-linear bonding elements as claimed in claim 4, wherein: Based on the non-linear constitutive algorithm, the method of endowing the first grid element group with the properties of non-linear elements so that the first grid element has the ability of elastoplastic deformation is as follows: In the geological exploration data of the seawall section, obtain the physical and mechanical parameters of each layer of soil at the pond foundation and the backfill soil of the pond; Based on the physical and mechanical parameters, establish the Mohr-Coulomb yield criterion; According to the Mohr-Coulomb yield criterion, set the model parameters, including normal stiffness, tangential stiffness, interface adhesion, friction coefficient of the interface, and isotropic hardening parameters; Based on the elastic part and the plastic part, calculate the interface tangential displacement; Based on the elastic part and the tangential stiffness, calculate the interface shear stress; Based on the normal stiffness and the interface normal displacement, calculate the interface normal stress Based on the interface shear stress, interface normal stress, friction coefficient of the interface, interface adhesion, isotropic hardening parameters, and cumulative tangential displacement, calculate the flow criterion value; When the flow criterion value is less than zero for the interface tangential behavior, the first grid element is in the elastic stage, and the plastic part of the tangential displacement remains unchanged; When the flow criterion value is equal to zero for the interface tangential displacement, the plastic part of the first grid element begins to accumulate, and the plastic displacement increment on the yield surface obeys the Mohr-Coulomb yield criterion; According to the flow criterion value, endow the contact surface of the first grid element group with the properties of non-linear elements, so that the first grid element has the ability of elastoplastic deformation, and realize the simulation of the contact and friction interaction process of the first grid element group.

6. The method for evaluating the structural safety of an ancient seawall based on non-linear bonding elements as claimed in claim 1, wherein: Based on the non - linear constitutive algorithm, endow the second grid cell group with the properties of non - linear elements, so that the second grid cells have damage characteristics. The method for obtaining the second bonding unit group is as follows: Obtain the data of the bonding structure of the stone blocks from the data of the seawall body materials; The data of the bonding structure of the stone blocks at least includes interface pressure, density, elastic modulus and Poisson's ratio; Based on the data of the bonding structure of the stone blocks, generate the stress - strain curve of the stone blocks, which is used to characterize the strength of the glutinous rice mortar bonding the stone blocks; According to the stress - strain curve of the stone blocks, determine the interface tangential stiffness, normal stiffness and the ultimate tensile strength of the interface; Based on the normal stiffness and the softening slope, establish the variation relationship between the normal stress of the constitutive interface and the interface normal displacement; Based on the interface tangential stiffness, the ultimate tensile strength of the interface and the control parameter, establish the variation relationship between the interface tangential stress, the interface tangential displacement and the interface normal displacement, that is, the normal cracking - tangential stiffness relationship; According to the variation relationship between the normal stress of the constitutive interface and the interface normal displacement, and the normal cracking - tangential stiffness relationship, endow the second grid cell group with the properties of non - linear elements, which is used to simulate the bonding effect between the stone blocks, so that the second grid cells have damage characteristics, and thus obtain the second bonding unit group.

7. The method for safety assessment of ancient seawall structures based on non - linear bonding elements according to claim 6, characterized in that: The variation relationship between the normal stress of the constitutive interface and the interface normal displacement includes the following contents: When the interface normal displacement exceeds the critical damage displacement, damage begins to occur in the interface normal direction; When the interface normal displacement reaches the fracture limit value, the interface normal fractures; With the evolution of the interface normal damage, the critical damage displacement gradually evolves from the initial displacement value to the normal fracture threshold; The evolution of the interface normal stress is divided into four stages, which include the normal elastic behavior under the interface compression state, the normal elastic behavior under the interface normal opening state, the normal damage behavior under the interface normal opening state and the stage of complete tangential rupture of the interface; Or / and, the normal cracking - tangential stiffness relationship includes the following contents: By adjusting the control parameter, different normal cracking - tangential stiffness relationships are constructed; when the control parameter is equal to zero and the normal displacement is greater than zero, the tangential stiffness of the interface immediately drops to zero; when the control parameter is equal to two, the tangential stiffness of the interface is independent of the interface normal displacement and remains constant all the time; The evolution of the interface tangential stress is divided into three stages, which include the tangential elastic behavior under the interface compression state, the tangential elastic behavior under the interface normal opening state and the stage of complete tangential rupture of the interface.

8. The method for safety assessment of ancient seawall structures based on non - linear bonding elements according to claim 7, characterized in that: Step four, use the previously constructed seawall deformation simulation model, apply the load to the bonding elements, and perform simulation calculations using the elastoplastic algorithm. The method for obtaining the structural deformation data of the seawall is as follows: Obtain the loads received by the seawall, which include hydrostatic pressure, wave force and the back - pond surcharge force; Set the displacement boundary conditions, which include the vertical restricted displacement at the bottom and the horizontal restricted displacements on both sides; Apply the load and displacement boundary conditions to the bonding elements, conduct a simulation analysis, and obtain the maximum displacement of the pond body and the maximum shear stress between the stone blocks. Couple the maximum displacement of the pond body and the maximum shear stress between the stone blocks to obtain the structural deformation data of the seawall.

9. A method for evaluating the structural safety of an ancient seawall based on non-linear bonding elements, characterized in that: It includes the following: Through the pre-constructed seawall grid generation model, draw the geometric models of the stone blocks, the soil behind the pond, and the soil at the bottom of the pond of the ancient seawall according to the latest drawing of the cross-section of the ancient seawall, divide the finite element grid, and obtain the pond body grid and the soil grid; then merge the nodes of the pond body grid and the soil grid, and set the parameters of each layer of soil, each level of stone blocks, and the bonding material according to the survey and test data to obtain the seawall simulation grid. Adopt the pre-constructed seawall attribute simulation model to obtain the bonding elements between the pond body and the soil and the bonding elements between the stone blocks based on the seawall simulation grid. Use the pre-constructed seawall deformation simulation model, apply the load to the bonding elements, and conduct a simulation calculation using the elastoplastic algorithm to obtain the structural deformation data of the seawall; then analyze the structural deformation data of the seawall to obtain the safety assessment information of the seawall structure, and complete the safety assessment of the ancient seawall structure based on non-linear bonding elements.

10. A system for evaluating the structural safety of an ancient seawall based on non-linear bonding elements, characterized in that: It includes: One or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method for evaluating the structural safety of an ancient seawall based on non-linear bonding elements as described in any one of claims 1-9.

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