Finite element analysis method for reducing tensile stress of concrete through transverse joint grouting
By using the finite element method, a transverse joint grouting area was set up and elastic support was applied to simulate the impact of transverse joint grouting on a concrete gravity dam. This solved the problem of the difficulty in quantifying the effect of transverse joint grouting, and achieved a reduction in the amount of steel reinforcement used in the flow channel and a simplification of construction.
Patent Information
- Application Number
- CN202511548616.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-28
- Publication Date
- 2026-01-27
AI Technical Summary
Existing technologies make it difficult to quantify the effect of transverse joint grouting on reducing tensile stress in the spillway section of a concrete gravity dam, which makes it difficult to design the amount of steel reinforcement in the channel and increases construction complexity.
A concrete gravity dam model was established using the finite element method. A transverse joint grouting area was set up, and elastic supports were applied to the side surface of the model to simulate the effect of transverse joint grouting on the dam section. Static structural analysis was performed to evaluate the stress results in the flow channel.
The effect of transverse joint grouting on reducing tensile stress in concrete was quantified, reducing the amount of steel reinforcement in the flow channel, improving structural stability, and simplifying the construction process.
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Figure CN121413074A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete gravity dam technology, and is particularly applicable to the finite element analysis method for reducing tensile stress in concrete by grouting transverse joints. Background Technology
[0002] A concrete gravity dam is a type of dam that relies on its own weight for stability. Its defining characteristic is the division of the dam into sections by transverse joints perpendicular to the dam's axis, allowing each section to function independently. These transverse joints are typically permanent and can simultaneously serve as settlement joints, temperature joints, and construction joints to accommodate variations in pouring capacity, uneven foundation settlement, and temperature changes. The presence of these transverse joints also helps control the stability and safety of the concrete gravity dam, preventing cracking caused by factors such as pouring capacity, uneven foundation settlement, and temperature variations.
[0003] However, the presence of transverse joints also reduces the overall integrity of the concrete dam, decreases the lateral stiffness of individual dam sections, and increases the deformation and stress of the concrete dam under load. This is especially true for functional dam sections with flow channels, leading to significant tensile stress in the concrete within the channels. Concrete is a brittle material that is resistant to compression but not tension, making it prone to cracking under tensile stress. To resist the tensile stress generated by the imbalance of internal and external water pressure within the flow channels, multiple layers of large-diameter steel reinforcement are often required, which greatly complicates construction.
[0004] Currently, transverse joint grouting is an effective means of reducing tensile stress in the concrete of spillway dam sections. By pre-embedding grouting pipes and then grouting later, the transverse joint voids are filled, restoring the integrity of the dam body and improving stress distribution, thereby enhancing structural stability. However, in practical design work, it is difficult to quantify the extent to which transverse joint grouting reduces the tensile stress on the concrete, and therefore, it is impossible to design the amount of steel reinforcement in the spillway based on the effect of transverse joint grouting. If a quantitative analysis method could be provided to reduce the tensile stress in concrete through transverse joint grouting, it would effectively guide the design work, reduce the amount of steel reinforcement, and facilitate construction. Summary of the Invention
[0005] The purpose of this invention is to provide a finite element analysis method for reducing tensile stress in concrete through transverse joint grouting, which can be used to solve the problem of large reinforcement and difficult construction in the spillway section of concrete gravity dams.
[0006] To achieve the above objectives, the finite element analysis method for reducing tensile stress in concrete by transverse joint grouting as described in this invention includes the following steps: S1. Establish a model of the spillway section and foundation of a concrete gravity dam. The dam section is divided into side surfaces according to the flow channel characteristics and a transverse joint grouting area is set. S2, import the spillway section and foundation model established in step S1 into the finite element software and set the numerical simulation parameters; S3: Mesh the spillway section and foundation model, and refine the mesh inside the flow channel; S4: Apply boundary conditions to the spillway section and foundation model. The boundary conditions include constraints and loads, as well as apply elastic support to the side surface of the spillway section to simulate the effect of transverse joint grouting on the dam section. S5: Use finite element software to analyze and solve the static structure of the model; S6: Review and evaluate the stress results at the inlet, channel, and outlet sections of the spillway.
[0007] Furthermore, the flow channel features include either a long pressurized section or a short pressurized section.
[0008] Furthermore, the transverse joint grouting area is designed to cover areas of excessive tensile stress in the concrete within the flow channel, including the inlet section, the flow channel section, and the outlet section, and the transverse joint grouting area is designed to be continuous, regular in shape, and easy to construct.
[0009] Furthermore, for long pressurized channels, at 10m above the highest point of the channel top surface or at the bend point, the side surface of the dam section is divided, and the horizontal upper boundary of the transverse joint grouting area is set; at 10m below the lowest point of the channel bottom surface, the side surface of the dam section is divided, and the horizontal lower boundary of the transverse joint grouting area is set; the upstream surface of the dam serves as the vertical left boundary of the transverse joint grouting area; and the downstream surface of the dam serves as the vertical right boundary of the transverse joint grouting area.
[0010] Furthermore, for short pressurized channels, at 10m above the highest point of the channel top surface or at the bend point, the horizontal upper boundary of the transverse joint grouting area is set on the side surface of the dam section; at 10m below the lowest point of the channel bottom surface, the horizontal lower boundary of the transverse joint grouting area is set on the side surface of the dam section; the upstream surface of the dam serves as the vertical left boundary of the transverse joint grouting area; the downstream surface of the dam, or at the downstream bend point, or 10m to the right after the pressurized section in the channel ends, serves as the vertical right boundary of the transverse joint grouting area.
[0011] Furthermore, in step S4, the constraints include full constraint on the foundation surface and constraint on the normal displacement of the foundation side surfaces. The loads include self-weight, hydrostatic pressure, uplift pressure, silt pressure, and seismic load. Elastic supports are applied to the side surfaces of the segmented spillway section to simulate the effect of transverse joint grouting on the dam section.
[0012] Furthermore, based on the foundation stiffness S of the dam's side surface, the elastic support is applied, and the calculation formula is as follows: ,in The length of adjacent dam sections is in mm. The elastic modulus of adjacent dam sections, in N / mm. 2 ; This is the reduction factor.
[0013] The advantage of this invention lies in simulating the effect of transverse joint grouting on the dam section by applying elastic support to the side surface of the dam section. Quantitative calculation results show that transverse joint grouting can increase the lateral stiffness of the dam section, improve the stress state of the concrete, reduce the tensile stress in the concrete within the flow channel, thereby reducing the amount of steel reinforcement required in the flow channel, making it safe, economical, and convenient for construction. Attached Figure Description
[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention and are used to explain the present invention.
[0015] Figure 1 This is a flowchart of the method described in this invention.
[0016] Figure 2 This is a schematic diagram of the transverse joint grouting area in the long pressurized flow channel dam section of the method described in this invention.
[0017] Figure 3 This is a schematic diagram of the transverse joint grouting area in the short pressurized flow channel dam section of the method described in this invention.
[0018] Figure 4 The stress profiles of the inlet section of the long pressurized flow channel before (a) and after (b) transverse joint grouting are compared using the method described in this invention.
[0019] Figure 5 The stress comparison diagrams of the long pressurized flow channel gate groove before (a) and after (b) transverse joint grouting are obtained by comparing the cross-sectional stress of the gate groove before (a) and after (b) transverse joint grouting using the method described in this invention.
[0020] Figure 6 The stress profiles of the breast wall with a long pressurized flow channel before (a) and after (b) transverse joint grouting are compared using the method described in this invention.
[0021] Figure 7 The stress comparison diagrams of the short pressurized flow channel inlet profile before (a) and after (b) transverse joint grouting are obtained by comparing the stress of the transverse joint before (a) and after (b) transverse joint grouting using the method described in this invention.
[0022] Figure 8 The stress comparison diagrams of the short pressurized flow channel gate groove before (a) and after (b) transverse joint grouting are shown using the method described in this invention.
[0023] Figure 9 The stress comparison diagrams of the short pressurized flow channel breast wall before (a) and after (b) transverse joint grouting are shown using the method described in this invention. Detailed Implementation
[0024] The finite element analysis method for reducing tensile stress in concrete by transverse joint grouting as described in this invention, such as... Figure 1As shown, it includes the following steps: S1. Establish the spillway section and foundation model of the concrete gravity dam. During the modeling stage, based on the characteristics of the long or short pressurized flow channels of the dam section, divide the side surface of the dam section and set the transverse joint grouting area.
[0025] The transverse joint grouting area needs to cover all tensile stress areas of the concrete within the flow channel. These areas mainly include the inlet section, the flow channel section, and the outlet section. Furthermore, the transverse joint grouting area must be a continuous, regular shape, and easy to construct.
[0026] The specific boundaries for the transverse joint grouting area of the long pressurized flow channel are as follows: 10m above the highest point of the flow channel top surface or at the bend point, the horizontal upper boundary of the transverse joint grouting area is set by dividing the side surface of the dam section; 10m below the lowest point of the flow channel bottom surface, the horizontal lower boundary of the transverse joint grouting area is set by dividing the side surface of the dam section; the upstream surface of the dam serves as the vertical left boundary of the transverse joint grouting area; and the downstream surface of the dam serves as the vertical right boundary of the transverse joint grouting area.
[0027] The specific boundaries for the transverse joint grouting area in the short pressurized flow channel are as follows: 10m above the highest point of the flow channel top surface or at the bend point, the horizontal upper boundary of the transverse joint grouting area is set by dividing the side surface of the dam section; 10m below the lowest point of the flow channel bottom surface, the horizontal lower boundary of the transverse joint grouting area is set by dividing the side surface of the dam section; the upstream surface of the dam serves as the vertical left boundary of the transverse joint grouting area; the downstream surface of the dam, or at the downstream bend point, or 10m to the right after the pressurized section in the flow channel ends, serves as the vertical right boundary of the transverse joint grouting area.
[0028] S2. Import the spillway section and foundation model established in step S1 into the finite element software and set parameters such as density, elastic modulus and Poisson's ratio.
[0029] S3, mesh the spillway section and foundation model, and refine the mesh inside the flow channel.
[0030] S4, apply boundary conditions to the spillway section and foundation model, including constraints and loads, and apply elastic support to the side surface of the spillway section to simulate the effect of transverse joint grouting on the dam section.
[0031] Constraints are applied to the spillway section and foundation model, including full constraint on the foundation surface and constraint on the normal displacement of the foundation sides; no constraints are applied to the dam body. Loads are applied to the spillway section and foundation model, including self-weight, hydrostatic pressure, uplift pressure, silt pressure, and seismic loads.
[0032] In addition to constraints and loads, elastic supports need to be applied to the segmented dam side surfaces to simulate the effect of transverse joint grouting on the dam sections. The elastic supports treat adjacent dam sections as springs, connecting them to the target dam section, increasing the lateral stiffness of the target dam section, limiting its lateral deformation, and thus reducing the tensile stress in the concrete within the flow channel.
[0033] The key to applying elastic support lies in determining its physical parameters—foundation stiffness. (N / mm³), the following is the derived formula: When an object is subjected to tension (compression), according to the linear elastic material mechanics formula: (Formula 1) When the volume of an object changes, according to the definition of basic stiffness S: (Formula 2) Combining equations (1) and (2), we get: (Formula 3) Because the adjacent dam sections are cantilever structures, and the target dam section is not an ideal spring, its ability to restrict deformation weakens with increasing height. Therefore, based on (Equation 3), a reduction factor is considered. : (Formula 4) In the formula: —Length change, mm; — Length of adjacent dam sections, mm; —The force acting on the object, in N; — Elastic modulus of adjacent dam sections, N / mm 2 ; —Cross-sectional area, mm 2 ; —Basic stiffness, N / mm³; —Volume change, mm 3 ; —Reduction factor.
[0034] S5: Based on the constraints, loads, and elastic supports of the spillway section and foundation model, the static structure of the model is analyzed and solved using finite element software.
[0035] S6: Review and evaluate the stress results at locations such as the inlet section, portal section, and breast wall section of the spillway.
[0036] To verify the reliability of the finite element analysis method for reducing tensile stress in concrete by transverse joint grouting as described in this invention, numerical simulations were performed on both long and short pressurized dam sections.
[0037] Taking a long pressurized channel dam section as an example, under constrained and loaded conditions and with a certain head, the stress along the dam axis in the inlet section, portal section, and breast wall section of the channel is analyzed. Figure 4 , 5 As shown in Figure 6, without transverse joint grouting, the maximum tensile stress along the dam axis at the inlet section is 7.96 MPa, which is greater than 0.45 MPa. ( The tensile stress zone (design value of concrete tensile strength) is approximately 8m high. The maximum tensile stress along the dam axis in the portal section is 5.66MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 6 meters high. The maximum tensile stress along the dam axis in the breast wall section is 6.58 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 7.5m high.
[0038] After adopting transverse joint grouting, the maximum tensile stress along the dam axis in the inlet section is 3.44 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 4 meters high. The maximum tensile stress along the dam axis in the portal section is 2.78 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 3 meters high. The maximum tensile stress along the dam axis in the breast wall section is 3.51 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 4m high.
[0039] Taking a short pressurized channel dam section as an example, under constrained and loaded conditions and with a certain head, the stress along the dam axis in the inlet section, portal section, and breast wall section of the channel is analyzed. Figure 7 , 8 As shown in Figure 9, without transverse joint grouting, the maximum tensile stress along the dam axis in the inlet section is 3.58 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 5 meters high. The maximum tensile stress along the dam axis in the portal section is 3.26 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 4 meters high. The maximum tensile stress along the dam axis in the breast wall section is 2.40 MPa, which is greater than 0.45 MPa. The tensile stress zone is approximately 4m high.
[0040] After adopting transverse joint grouting, the maximum tensile stress along the dam axis in the inlet section is 1.89 MPa, which is greater than 0.45 MPa. ( The tensile stress zone (design value of concrete tensile strength) is approximately 2m high. The maximum tensile stress along the dam axis in the portal section is 1.84MPa, greater than 0.45 MPa. ( The tensile stress zone (design value of concrete tensile strength) is approximately 2m high. The maximum tensile stress along the dam axis in the breast wall section is 1.38MPa, greater than 0.45 MPa. The height of the tensile stress zone is approximately 1.8m.
[0041] The finite element analysis method for reducing concrete tensile stress by transverse joint grouting as described in this invention can quantitatively analyze how much concrete tensile stress can be reduced by transverse joint grouting, thereby providing reliable data guidance for engineering design and construction, making engineering design and construction management more refined, and achieving the goals of reducing the amount of steel reinforcement used in the flow channel, ensuring safety and economy, and facilitating construction.
Claims
1. A finite element analysis method for reducing tensile stress in concrete through transverse joint grouting, characterized in that, Includes the following steps: S1. Establish a model of the spillway section and foundation of a concrete gravity dam. The model is divided into the side surface of the dam section according to the characteristics of the flow channel and a transverse joint grouting area is set. S2, import the spillway section and foundation model established in step S1 into the finite element software and set the numerical simulation parameters; S3: Mesh the spillway section and foundation model, and refine the mesh inside the flow channel; S4: Apply boundary conditions to the spillway section and foundation model. The boundary conditions include constraints and loads, as well as apply elastic support to the side surface of the spillway section to simulate the effect of transverse joint grouting on the dam section. S5: Use finite element software to analyze and solve the static structure of the model; S6: Review and evaluate the stress results of the inlet section, portal section, and breast wall section of the spillway.
2. The finite element analysis method for reducing tensile stress in concrete by grouting transverse joints according to claim 1, characterized in that: The flow channel features include either long pressurized or short pressurized channels.
3. The finite element analysis method for reducing tensile stress in concrete by grouting across transverse joints according to claim 1, characterized in that: The transverse joint grouting area is designed to cover areas of excessive tensile stress in the concrete within the flow channel, including the inlet section, flow channel section, and outlet section, and must be designed to be continuous, regularly shaped, and easy to construct.
4. The finite element analysis method for reducing tensile stress in concrete by transverse joint grouting according to claim 2, characterized in that: For long pressurized channels, at 10m above the highest point of the channel top surface or at the bend point, the side surface of the dam section is divided, and the horizontal upper boundary of the transverse joint grouting area is set; at 10m below the lowest point of the channel bottom surface, the side surface of the dam section is divided, and the horizontal lower boundary of the transverse joint grouting area is set; the upstream surface of the dam serves as the vertical left boundary of the transverse joint grouting area; and the downstream surface of the dam serves as the vertical right boundary of the transverse joint grouting area.
5. The finite element analysis method for reducing tensile stress in concrete by transverse joint grouting according to claim 2, characterized in that: For short pressurized channels, the horizontal upper boundary of the transverse joint grouting area is set 10m above the highest point of the channel top surface or at the bend point. The horizontal lower boundary of the transverse joint grouting area is set 10m below the lowest point of the channel bottom surface. The upstream surface of the dam serves as the vertical left boundary of the transverse joint grouting area. The downstream surface of the dam, or the downstream bend point, or 10m to the right after the pressurized section in the channel ends, serves as the vertical right boundary of the transverse joint grouting area.
6. The finite element analysis method for reducing tensile stress in concrete by grouting across transverse joints according to claim 1, characterized in that: In step S4, the constraints include full constraints on the foundation surface and normal displacement constraints on the foundation side; the loads include self-weight, hydrostatic pressure, uplift pressure, silt pressure, and seismic load; elastic supports are applied to the side surfaces of the segmented spillway section to simulate the effect of transverse joint grouting on the dam section.
7. The finite element analysis method for reducing tensile stress in concrete by transverse joint grouting according to claim 1, characterized in that: The elastic support is applied based on the foundation stiffness S of the dam's side surface, and the calculation formula is as follows: ,in The length of adjacent dam sections is in mm. The elastic modulus of adjacent dam sections, in N / mm. 2 ; This is the reduction factor.