An intelligent prediction method for dredging scheme based on characteristics of siltation shear

Abstract

This invention discloses an intelligent prediction method for dredging schemes based on the shear characteristics of backfill material, belonging to the field of underwater engineering backfill management and dredging technology. The method of this invention obtains backfill material parameters through experiments and performs shear tests to obtain τ. k Establish τ k The conversion relationship with the base pressure is used to determine the economic pressure window; then, the τ-value is established. k With economic dredging thickness H e The mapping yields the residual thickness control target H. std After outputting a preliminary plan based on the pressure window, the plan is verified and iteratively corrected using average thickness and variance until the final dredging plan is output. This invention transforms the dredging standard from empirical thickness or a single bulk density threshold into a parameterized standard based on shear characteristic curves, making the determination of "how thick to dredge for maximum economy" calculable and reusable across different projects.

Description

Technical Field

[0001] This invention relates to the field of underwater engineering siltation control and dredging technology, and in particular to an intelligent prediction method for dredging schemes based on the shear characteristics of silt. Background Technology

[0002] In the construction of gravity-type underwater structures such as immersed tubes, caissons, and breakwaters, siltation of the foundation trench is a common problem. In engineering practice, "density + maximum thickness" or a uniform residual thickness is often used as the standard for silt removal. However, such standards assume that "the same density = the same compressible / cleanable state," easily ignoring the differences in particle composition, structure, and rheology of silt from different sea areas. This can lead to over-dredging, resulting in increased construction time and disposal costs, or under-dredging, causing poor contact, localized weak interlayers, and uneven settlement risks. Summary of the Invention

[0003] The purpose of this invention is to address the technical deficiencies in the existing technology by providing an intelligent prediction method for dredging schemes based on the shear characteristics of backfill material.

[0004] The technical solution adopted to achieve the purpose of this invention is: A smart prediction method for dredging schemes based on the shear characteristics of silt includes the following steps: Step 1: Based on the corresponding working conditions, take the backfill material at the target location, set the boundary constraints and subgrade conditions, clarify the contact geometry and loading method of the gravity structure, establish an indoor test model, and obtain the physical property parameters of the backfill material. Step 2: Conduct a shear characteristic test on the silt to obtain the x–τ curve between the equivalent shear parameter x and the shear stress τ, and preprocess the x–τ curve. Step 3: Determine the critical shear stress τ based on the pre-processed x–τ curve. k ; Step 4: Establish the critical shear stress τ through indoor test models and / or simulation analysis. k The equivalent conversion relationship between the base pressure and the target foundation trench is given, and the pressure window margin δ is set in combination with the allowable deviation of the engineering to provide an economic pressure window. Step 5, establish the critical shear stress τ k With economic dredging thickness H e The mapping relationship between them is used to calculate the economic dredging thickness H. e Based on the economic dredging thickness H e The target H for controlling the thickness of residual silt was obtained. std In light of the economic pressures, a preliminary dredging plan was developed. Step 6: Record the average residual thickness and the squared difference of the residual thickness of the sludge in the indoor test model. When the average residual thickness reaches or is less than H... stdWhen the residual thickness variance is less than the set range, record the corresponding base pressure p0 and the time to reach the standard t0. If the two parameters exceed the set range, backtrack and correct the corresponding working condition parameters in steps 2-5, iterate and update the preliminary dredging plan until the two parameters are within the set range, and output the final dredging plan.

[0005] In the above technical solution, in step 1, when the bottom surface of the target trench of the indoor test model is regular and the sinking contact is stable, the loading method can be equivalent to the application of a uniform surface load.

[0006] In the above technical solution, in step 1, the physical property parameters include bulk density ρ, initial thickness h0, and moisture content.

[0007] In the above technical solution, in step 2, the equivalent shear parameter x includes the shear drive strength, shear rate, or equivalent shear index obtained by converting experimental data during the backfill material extrusion process.

[0008] In the above technical solution, step 2, the preprocessing process involves denoising the x–τ curve, screening for steady-state segments, and performing repeatability checks to ensure the curve shape is stable and remains constant for τ. k This provides the sole basis for certainty.

[0009] In the above technical solution, in step 3, the x–τ curve is fitted by two segments of a broken line or a smooth curve. When the x–τ curve is fitted by two segments of a broken line, the shear stress corresponding to the intersection of the broken line segments is taken as τ. k When the x–τ curve is a smooth curve, the shear stress corresponding to the point of maximum curvature is determined by curvature analysis as τ. k .

[0010] In the above technical solution, in step 4, the equivalent conversion relationship is: p*=τ k / C, where p* is τ k The corresponding base pressure is denoted as the economic base pressure, and C is the conversion factor.

[0011] In the above technical solution, in step 4, the economic pressure window is represented as [p min , p max ], p min =p*·(1-δ), p max = p*·(1+δ), where p min p represents the minimum economic base pressure. max This represents the maximum value of economic base pressure.

[0012] In the above technical solution, in step 5, the mapping relationship is: H e =f(τ k(corresponding parameters), where the economic dredging thickness H e The dredging thickness is used to characterize the dredging thickness that results in less external dredging, faster compliance, and lower energy consumption while meeting extrusion acceptance and risk constraints. The corresponding parameters include bulk density ρ, boundary constraints, bed conditions, or loading method.

[0013] In the above technical solution, in step 5, H std =H e +H c H c The maximum allowable residual thickness of silt without affecting the structural safety and contact performance during immersion.

[0014] In the above technical solution, in step 6, an indoor test model and / or simulation analysis are used for simulation verification. When p0 exceeds the economic pressure window, t0 is less than or equal to the preset allowable time t. lim If so, it means that both parameters are out of the set range.

[0015] In the above technical solution, in step 6, when the on-site backfill thickness Ha > H std Dredging should be initiated when Ha ≤ H. std It can directly enter the silt-drainage construction and be loaded within the economic window.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) The dredging standard is transformed from empirical thickness or single bulk density threshold into a parameterized standard based on shear characteristic curve, so that "how thick to dredge is the most economical" has a calculable basis and can be reused in different projects. (2) Using the critical shear stress τ k With this as the core, the information obtained from the experiment is further refined into the economic dredging thickness He and the economic pressure window [p] min , p max This makes loading control more bounded, reducing repeated trial and error and overloading; (3) H e The maximum allowable residual silt thickness H without affecting the structural safety and contact performance during immersion. c Combined to form residual thickness control target H std Furthermore, it is integrated with the economic pressure window for output, and construction and supervision can be inspected using the same standard to reduce the risk of local outstanding payments; (4) Based on the existing large-scale test / numerical simulation results, a mapping rule of "shear characteristics - thickness - pressure" is formed, which can be continuously supplemented according to engineering data to form a standard library, providing rapid and intelligent recommendations for dredging standards under different bulk density, different boundaries and different bed conditions. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the method of the present invention.

[0018] Figure 2 The diagram shows the finite element analysis model of the present invention at different loading times.

[0019] Figure 3 The deep-middle channel silt return material of the present invention curve.

[0020] Figure 4 The present invention relates to a port silt return material. curve. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] Example 1 A smart prediction method for dredging schemes based on the shear characteristics of silt includes the following steps: like Figure 1 As shown, in step 1, based on the specific working conditions, take the silt from the target location, set boundary constraints and subgrade conditions, clarify the contact geometry and loading method of the gravity structure, establish an indoor test model, and simultaneously obtain the physical property parameters of the silt, and determine the layout of measuring points and data acquisition aperture of the indoor test model; the physical property parameters (including unit weight ρ, initial thickness h0, and moisture content, etc.); preferably, when the bottom surface of the target trench of the indoor test model is regular and the sinking contact is stable, the loading method can be equivalent to the application of a uniform surface load.

[0023] Preferably, in this embodiment, the target trench of the indoor test model is 1 m long, 1 m wide, and 0.8 m high. The bottom is covered with 13 cm thick gravel with a particle size of 5-10 mm, and the top is covered with 5 cm thick gravel with a density of 12.2 kN / m³. 3 The silt was simulated using a tempered glass plate, which was 0.5 m long and 0.5 m wide. The vertical load applied to the silt by the tempered glass plate was determined according to the specific working conditions. The silt at the target location was selected from typical silt from the Shenzhen-Zhongshan Bridge and a port. Different density working conditions were formed by adding water and adjusting the mixture. The initial silt thickness and base pressure level were set according to the working condition table, and the boundary constraints were defined.

[0024] Step 2: Using a DV-I type rotational viscometer, shear characteristic tests were conducted on silt samples from the Shenzhen-Zhongshan Channel and a port to obtain the shear rate and shear stress. Between Curve, for The curve undergoes denoising, steady-state segment screening, and repeatability verification to ensure curve shape stability. This provides the sole basis for certainty.

[0025] Step 3, based on the preprocessed The curve determines the critical shear stress τ k ; wherein, the The curve is fitted by two broken lines, and the shear stress corresponding to the intersection of the broken line segments is taken as τ. k .

[0026] like Figures 3-4 The images shown are of silt deposits from the Shenzhen-Zhongshan Bridge and a port, respectively. The curves represent the shear rate on the horizontal axis, characterizing the deformation rate of the backfill material under shear stress; and the shear stress τ on the vertical axis, characterizing the ability of the backfill material to resist shear deformation. The three curves represent 12.6 kN / m... 3 13.0 kN / m 3 and 14.1 kN / m 3 The shear response of backfill material under specific density conditions is shown in the figure. The figure illustrates the variation of shear stress with shear rate for backfill material of different regions and densities. The transition point from the rapid change stage to the slow change stage in the figure can be used as a characteristic point for the change in shear characteristics and to determine the critical shear stress τ. k The τ k This will be further used in the calculation of subsequent economic pressure windows and the thickness of economic dredging.

[0027] Step 4: Based on the indoor test model, establish the corresponding finite element analysis model, apply a vertical load to the silt to simulate the immersed tube, compare the simulation experiments of the indoor test model and the finite element analysis model, and establish the critical shear stress τ. k The equivalent conversion relationship between p* and base pressure is p*=τ k / C, where p* is τ k The corresponding base pressure is denoted as the economic base pressure, and C is the conversion factor.

[0028] Furthermore, a vertical load is applied to the finite element model corresponding to the indoor test model, and the shear response at the sinking interface is extracted. The conversion factor C is obtained by regression of "interface equivalent shear stress - base pressure". Based on τ obtained in step 3, k The economic base pressure p* is calculated; combined with the allowable deviation of the project, the pressure window margin δ = 1% is set to obtain the economic pressure window [p]. min , p max ], p min =p*·(1-δ), p max = p*·(1+δ), where p min p represents the minimum economic base pressure.max The maximum economic base pressure is defined as follows: when the boundary constraints are high, the single-stage pressurization amplitude can be appropriately reduced and the steady-state holding time extended to reduce the risks of backflow, accumulation, and local unevenness. Here, the boundary constraints refer to the degree of restriction on the discharge of silt by slopes, trench walls, silt discharge channels, and collection spaces; the single-stage pressurization amplitude refers to the increment of the base pressure between two adjacent stages in staged loading; and the steady-state holding time refers to the time spent maintaining that pressure after each stage of pressure is applied and waiting for the silt to be discharged. Economic pressure window [p] min , p max This is used to limit the range of loading pressure. The stronger the boundary constraint, the smaller the single-stage pressure increase amplitude and the longer the steady-state holding time should be within this window. Preferably, this embodiment uses a slope condition as a representative of stronger constraints, and the loading is performed using a staged pressure increase-steady-state holding method.

[0029] Furthermore, such as Figure 2 As shown, a finite element analysis model was established to simulate the sinking and silt-dissipating process of a tempered glass plate. Only half of the model is shown in the figure, illustrating the sinking process of the same finite element analysis model at different loading times (0.15s, 0.2s, 0.3s, and 0.4s). In the figure, the red area represents the tempered glass plate, and the rest represents the silt.

[0030] Step 5, establish the critical shear stress τ k With economic dredging thickness H e Mapping relationship H e =f(τ) k , ρ), select several typical unit weights ρ commonly used in engineering (such as 11.5, 12.6, 13.0, 14.0 kN / m), 3 The relationship between the corresponding shear rate and shear stress τ Curve, determine τ one by one k And substitute it into the mapping relationship to obtain H for each unit weight condition. e Then, considering the maximum allowable residual sludge thickness H without affecting the structural safety and contact performance during slab placement. c The residual thickness control target H is obtained. std =H e +H c Specifically, the existing dredging control diameters in projects such as the Hong Kong-Zhuhai-Macau Bridge can be referenced, and minor adjustments can be made based on structural contact performance and allowable construction deviations. std With the window of economic pressure [p min , p max Based on this, a preliminary dredging plan is output, which serves as the dredging standard and loading control parameters under this type of siltation shear characteristic condition.

[0031] Step 6: Experiment-Simulation Consistency Verification and Data Archiving. Based on the preliminary dredging plan, simulated experiments were conducted using an indoor experimental model and a corresponding finite element model, applying the same vertical load. The settlement displacement-time curve, extrusion rate, and residual thickness changes were recorded. The consistency verification refers to comparing the experimental and simulated results to ensure that the residual sludge thickness reaches the target H. std The final residual thickness, required loading level, and required time are consistent. Specifically, the residual thickness of the indoor test model's immersion area is measured at multiple points, and the average residual thickness and residual thickness variance are calculated; when the average residual thickness reaches or is less than H... std When the residual thickness variance is less than the set range, record the corresponding base pressure p0 and the time to reach the standard t0, and determine whether p0 is within the economic pressure window [p min , p max Within [the specified time], determine whether t0 is less than or equal to the preset allowed time t. lim If the deviation between the two exceeds the above-mentioned set range, then a backtracking correction τ will be performed. k Identify and convert the coefficient C or the corresponding working condition parameters in the mapping relationship, iteratively update the dredging plan until the deviation between the two is within a set range, and output the final dredging plan. Finally, the shear curve and τ are... k p* and windows, H e / H std The results of the experiments and simulations are compiled into an example log for quick reference in subsequent projects.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for intelligent prediction of dredging schemes based on the shear characteristics of silt, characterized in that, Includes the following steps: Step 1: Based on the corresponding working conditions, take the backfill material at the target location, set the boundary constraints and subgrade conditions, clarify the contact geometry and loading method of the gravity structure, establish an indoor test model, and obtain the physical property parameters of the backfill material. Step 2: Conduct a shear characteristic test on the silt to obtain the x–τ curve between the equivalent shear parameter x and the shear stress τ, and preprocess the x–τ curve. Step 3: Determine the critical shear stress τ based on the pre-processed x–τ curve. k ; Step 4: Establish the critical shear stress τ through indoor test models and / or simulation analysis. k The equivalent conversion relationship between the base pressure and the target foundation trench is given, and the pressure window margin δ is set in combination with the allowable deviation of the engineering to provide an economic pressure window. Step 5, establish the critical shear stress τ k With economic dredging thickness H e The mapping relationship between them is used to calculate the economic dredging thickness H. e Based on the economic dredging thickness H e The target H for controlling the thickness of residual silt was obtained. std In light of the economic pressure window, a preliminary dredging plan was developed; Step 6: Record the average residual thickness and the squared difference of the residual thickness of the sludge in the indoor test model. When the average residual thickness reaches or is less than H... std When the residual thickness variance is less than the set range, record the corresponding base pressure p0 and the time to reach the standard t0. If the two parameters exceed the set range, backtrack and correct the corresponding working condition parameters in steps 2-5, iterate and update the preliminary dredging plan until the two parameters are within the set range, and output the final dredging plan.

2. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 1, when the bottom surface of the target trench of the indoor test model is regular and the sinking contact is stable, the loading method can be equivalent to the application of a uniform surface load; the physical property parameters include unit weight ρ, initial thickness h0 and moisture content.

3. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 2, the equivalent shear parameter x includes the shear drive strength, shear rate or equivalent shear index obtained by converting experimental data during the backfill material extrusion process. The preprocessing process involves: denoising the x–τ curve, screening the steady-state segment, and checking repeatability.

4. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 3, the x–τ curve is fitted by two segments of a broken line or a smooth curve; when the x–τ curve is fitted by two segments of a broken line, the shear stress corresponding to the intersection of the broken line segments is taken as τ. k When the x–τ curve is a smooth curve, the shear stress corresponding to the point of maximum curvature is determined by curvature analysis as τ. k .

5. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 4, the equivalent conversion relationship is: p*=τ k / C, where p* is τ k The corresponding base pressure is denoted as the economic base pressure, and C is the conversion factor.

6. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 4, the economic pressure window is represented as [p] min , p max ], p min =p ·(1-δ), p max ＝p *·(1+δ), where p min p represents the minimum economic base pressure. max This represents the maximum value of economic base pressure.

7. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 5, the mapping relationship is: H e =f(τ k (corresponding parameters), wherein the corresponding parameters include bulk density ρ, boundary constraints, subgrade conditions or loading method.

8. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 5, H std =H e +H c H c The maximum allowable residual thickness of silt without affecting the structural safety and contact performance during immersion.

9. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 6, simulation verification is performed using an indoor test model and / or simulation analysis. When p0 exceeds the economic pressure window, t0 is less than or equal to the preset allowable time t. lim If so, it means that both parameters are out of the set range.

10. The intelligent prediction method for dredging schemes according to claim 1, characterized in that, In step 6, when the on-site backfill thickness Ha > H std Dredging should be initiated when Ha ≤ H. std It can directly enter the silt-drainage construction and be loaded within the economic window.

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