Experimental device for studying service performance of pile-type dyke under surge load

Abstract

This invention discloses an experimental apparatus for studying the service performance of piled groynes under tidal loads. The apparatus includes a model box with polypropylene foam boards arranged on its four side walls and bottom to reduce boundary effects. A test model is positioned above the model box, with its lower end embedded in the middle of the soil. The test model is supported above the model box by a clamping assembly. The clamping assembly includes a transversely arranged support and vertical fixed supports fixedly connected to both ends of the transverse support. A slide rail is fixed on the transverse support, and a slider is mounted on the test model. The slide rail and slider cooperate to simulate the sliding support constraint conditions of the piled groynes. A hammer loading device is mounted on the transverse support. By striking the test model with the hammer, the test model generates a corresponding dynamic response, and the generated internal forces are collected by a dynamic data acquisition instrument. This invention can effectively study the service performance of piled groynes under tidal loads.

Description

Technical Field

[0001] This invention belongs to the field of load dynamics technology in areas with strong tidal bores, and in particular, it is an experimental device for studying the service performance of pile groynes under tidal bore loads. Background Technology

[0002] The Qiantang River tidal bore in my country is considered one of the world's largest. The Qiantang River flows into the East China Sea through the funnel-shaped Hangzhou Bay. Tidal water surges into the river from Hangzhou Bay, forming a tidal bore with a height of 1-4 meters, moving upstream for over 100 kilometers at a speed of 20-30 kilometers per hour. Tidal bore processes can have significant impacts on estuaries and their ecosystems. It affects sediment transport, leading to bank erosion and altering topographic features. Tidal bores can also impact shipping; for example, the Qiantang River tidal bore poses a threat to small vessels. Several disasters have occurred in the past due to the destructive power of tidal bores. To mitigate these adverse effects, numerous artificial structures have been built near rivers or estuaries to improve water flow. Groynes have been widely constructed perpendicular to the coastline and riverbanks to protect beaches and promote sedimentation. Traditional rock-filled groynes are easily damaged by tidal bore impacts. The main type of damage is base erosion.

[0003] To overcome these shortcomings, a novel sheet pile groynes (SPGs) were proposed and widely used in the Qiantang River. These groynes consist of parallel piles connected to beams at the top. The deep foundation of the pile groynes effectively avoids the problem of foundation erosion. However, as a novel hydraulic structure, the dynamic response of pile groynes under tidal loads is complex. Currently, there is no effective indoor experimental setup for studying the service performance of pile groynes under tidal loads. Summary of the Invention

[0004] To address the aforementioned technical problems in existing technologies, this invention provides an experimental device that is simple to operate and can effectively study the service performance of pile groynes under tidal loads.

[0005] The technical solution adopted in this invention is:

[0006] An experimental apparatus for studying the service performance of piled groynes under tidal loads, characterized in that it comprises:

[0007] The model box has an opening at the top, and polypropylene foam boards are arranged on the four internal side walls and the bottom to reduce the boundary effect of the model box; the model box is filled with soil, and the soil fills the entire model box.

[0008] The test model is located above the model box, with its lower end buried in the middle of the soil. The burial depth of the test model is 2 / 3 to 7 / 9 of the length of the groyne pile. The test model is supported above the model box by a clamping assembly. The clamping assembly includes a transversely arranged support and vertical fixed supports fixedly connected to both ends of the transverse support. A slide rail is fixed on the transverse support, and a slider is provided on the test model. The slide rail and the slider cooperate to simulate the sliding support constraint conditions of the pile groyne. A force hammer loading device is provided on the transverse support. The test model is struck by the force hammer loading device, and the test model generates a corresponding dynamic response. The generated internal forces are collected by a dynamic data acquisition instrument.

[0009] Furthermore, strain gauges are arranged on the test model, and the strain gauges are connected to the data acquisition instrument via wires.

[0010] Furthermore, one end of the slider is connected to the test model via an additional wing plate, and the slide rail is connected to the transverse support via bolts.

[0011] Furthermore, an optical displacement sensor is installed on the vertical fixed support, the optical displacement sensor is facing the horizontal direction of the connecting beam of the test model, and the optical displacement sensor is connected to the data dynamic acquisition instrument.

[0012] Furthermore, a speed sensor is provided on the upper surface of the soil material, and the speed sensor is connected to the data dynamic acquisition instrument.

[0013] Furthermore, the soil material is dry soil, filled in layers, and compacted in layers, and the density of the soil material is between the maximum density and the minimum density.

[0014] Furthermore, the method for calculating the bending moment at the strain gauge on the cross section is as follows:

[0015] The tensile strain ε was obtained through experiments. s ε compressive strain c Assuming that each plane section perpendicular to the axis of the rod remains a plane after deformation under tension, compression, or pure bending, and is perpendicular to the deformed axis of the rod, the experimental model satisfies the plane section assumption. Therefore, the neutral axis and the corresponding tensile strain ε can be determined. s The location distance y is:

[0016]

[0017] Where h is the width of the pile along the loading direction;

[0018] The curvature ρ of the neutral axis can be obtained as:

[0019]

[0020] The experimental model material was 6061 aluminum alloy. When the material was within the linear elastic range, according to Hooke's Law, we have:

[0021] σ s =Eε s

[0022] Where: E is the elastic modulus of the material, σ s This represents the tensile stress corresponding to the location of the tensile strain.

[0023] From the statics relationship, the bending moment M at the corresponding location can be obtained as:

[0024]

[0025] Where: I is the moment of inertia, and A is the cross-sectional area.

[0026] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0027] 1) By analyzing the experimental model data, the experimental conclusions can be approximately extended to pile groynes, reducing engineering costs.

[0028] 2) It is easy to operate and can effectively study the service performance of pile groynes under tidal load. Attached Figure Description

[0029] Figure 1a This is a front view of the structure of the testing device of the present invention;

[0030] Figure 1b This is a top view of the experimental model structure of the present invention;

[0031] Figure 2a , Figure 2b and Figure 2c These are, respectively, the front view, side view, and top view of the groyne structure of the experimental model of this invention;

[0032] Figure 3 This is a schematic diagram of the model box structure of the present invention;

[0033] Figure 4 This is a schematic diagram of the sliding support structure of the present invention;

[0034] Figure 5a , Figure 5b and Figure 5c These are, respectively, the front view, the side view, and the top view of the clamping component structure of the present invention;

[0035] Figure 6 This is a schematic diagram of the strain gauge arrangement position of the present invention;

[0036] Figure 7a This is a strain diagram of the A1 surface of the groyne pile body in the example model of this invention;

[0037] Figure 7b This is a strain diagram of the A2 surface of the groyne pile body in the example model of this invention;

[0038] Figure 7c This is a strain diagram of the B1 surface of the groyne pile body in the example model of this invention;

[0039] Figure 7d This is a strain diagram of the B2 surface of the groyne pile body in the example model of this invention;

[0040] Figure 8a This is a bending moment diagram of pile A in the groyne pile body of the example model of this invention;

[0041] Figure 8b This is a bending moment diagram of pile B in the groyne pile body of the example model of this invention. Detailed Implementation

[0042] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0043] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0044] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0045] refer to Figures 1a to 8b The present invention provides an experimental apparatus for studying the service performance of piled groynes under tidal load, comprising:

[0046] The model box 1 has an opening at the top, and polypropylene foam boards 12 are arranged on the four side walls and bottom of the interior to reduce the boundary effect of the model box. The model box 1 is filled with soil material 13, and the soil material fills the entire model box 1. Specifically, in this embodiment, the model box 1 has a size of 55cm×55cm×75cm, the material is a high transparency acrylic sheet, and the thickness of the polypropylene foam board 12 is 2mm. No water outlet or water inlet is provided.

[0047] The test model 7 is located above the model box 1, with its lower end buried in the middle of the soil material 13. The burial depth of the test model 7 is 2 / 3 to 7 / 9 of the length of the groyne pile. The test model 7 is erected above the model box 1 by a clamping assembly. The clamping assembly includes a transverse support 6 arranged laterally and a vertical fixed support 11 fixedly connected to both ends of the transverse support 6. A slide rail 10 is fixed on the transverse support 6, and a slider 9 is provided on the test model 7. The slide rail 10 and the slider 9 cooperate with each other to simulate the sliding support constraint conditions of the pile groyne. A force hammer loading device 8 is provided on the transverse support 6. The test model 7 is struck by the force hammer loading device 8, and the test model 7 generates a corresponding dynamic response, and the generated internal force is collected by the dynamic data acquisition instrument 4.

[0048] Specifically, the experimental model in this embodiment is a single spur on a pile-type groyne. Based on dimensional analysis, certain unknowns are selected as the basic dimensional system. According to the principle of dimensional homogeneity, the dimensions on both sides of the equation are consistent. Using the π theorem to ensure the similarity between the model and the prototype, the similarity relationship between the model and the prototype is obtained. The geometric scale of the model and the prototype in this experimental setup is selected as follows:

[0049] In one embodiment, strain gauges 3 are arranged on the test model 7, and the strain gauges 3 are connected to the data dynamic acquisition instrument 4 via wires.

[0050] Specifically, in this embodiment, the strain gauges 3 are arranged in two locations. The first location is on the pile body: the test model has two piles, A and B, each pile has two effective sections, A1 and B2, that is, a total of four effective sections: A1, A2, B1, and B2. Taking section A1 as an example: the first strain gauge is arranged starting 5cm from the bottom of the pile, and a strain gauge is arranged every 15cm, for a total of five (the remaining sections are the same as A1, such as...). Figure 6 (As shown in Figure 7); The second location is in the connecting beam: the first pair of strain gauges 3 are arranged in the middle of the connecting beam, and the second and third pairs of strain gauges 3 are arranged 5cm to the left and right of the middle of the connecting beam (two for each pair, arranged on the upper and lower surfaces of the connecting beam, as shown in Figure 7). Figure 6 (As shown). Strain gauge 3 is attached to the pile-type groyne test model using 502 adhesive. A layer of silicone sealant is applied to the outer layer of strain gauge 3 to ensure its normal operation.

[0051] In one embodiment, one end of the slider 9 is connected to the test model 7 via an additional wing plate 14, and the slide rail 10 is connected to the transverse support 6 by bolts.

[0052] In one embodiment, a light displacement sensor 5 is provided on the vertical fixed support 11. The light displacement sensor 5 is directly facing the horizontal direction of the connecting beam of the test model 7, and the light displacement sensor 5 is connected to the data dynamic acquisition instrument 4.

[0053] In one embodiment, a speed sensor 2 is provided on the upper surface of the soil material 13, and the speed sensor 2 is connected to the data dynamic acquisition instrument 4.

[0054] In one embodiment, the soil material 13 is dry soil, which is filled and compacted in layers, and the density of the soil material is between the maximum density and the minimum density.

[0055] In one embodiment, the method for calculating the bending moment at the strain gauge on the cross section is as follows:

[0056] The tensile strain ε was measured experimentally. s ε compressive strain c (like Figure 6 As shown in the figure, assuming that each plane section perpendicular to the axis of the rod, that is, the cross-section of the rod remains a plane after the rod is deformed by tension, compression or pure bending, and is perpendicular to the axis of the deformed rod, the test model satisfies the plane section assumption. Therefore, the neutral axis and the corresponding tensile strain ε can be determined. s The location distance y is:

[0057]

[0058] Where h is the width of the pile along the loading direction;

[0059] The curvature ρ of the neutral axis can be obtained as:

[0060]

[0061] The experimental model material was 6061 aluminum alloy. When the material was within the linear elastic range, according to Hooke's Law, we have:

[0062] σ s =Eε s

[0063] Where: E is the elastic modulus of the material, σ s This represents the tensile stress corresponding to the location of the tensile strain.

[0064] From the statics relationship, the bending moment M at the corresponding location can be obtained as:

[0065]

[0066] Where: I is the moment of inertia, and A is the cross-sectional area.

[0067] The bending moment curve of the pile body is shown below. Figure 8a and Figure 8bAs shown in the figure, the inflection points of piles A and B are located at roughly the same positions, around 7 / 9 of the pile length, which is roughly consistent with the embedment depth. The maximum bending moment values ​​of piles A and B are located at roughly the same positions, with the maximum positive bending moment occurring at about half the pile length and the maximum negative bending moment occurring at the pile top; however, the maximum bending moment values ​​of piles A and B are different, with the maximum positive and maximum negative bending moments of pile A being slightly smaller than those of pile B.

[0068] This invention, through the analysis of experimental model data, can approximately extend experimental conclusions to pile-type groynes, thereby reducing engineering costs.

[0069] The technical concept of this invention is as follows: During the experiment, the test model is buried deep in the soil. By adjusting the size of the model box, adding a polypropylene foam board, and adjusting the burial depth of the test model, the influence of the boundary effect of the model box on the experimental results is reduced. This experimental setup uses a 55cm×55cm×75cm model box and a 2mm thick polypropylene foam board, ensuring that the ratio of foam thickness to the width of the model box in the vibration direction is between 2% and 4%. This guarantees that the foam board can effectively reduce the boundary effect of the model box. Simultaneously, this experimental setup buries the model box at a distance from... At the bottom 45cm of the model box, the square pile is equivalent to a circle of equal area. When the distance between the pile bottom and the model box is greater than 3 times the diameter of the circle, the boundary effect of the model box can be ignored. The impact of the tidal load on the groyne is simulated by striking the test model with a hammer, and the sliding rail and slider simulate the sliding support constraint conditions of the groyne. The bending moment is calculated by strain measured by strain gauges, and the structural bearing capacity of the groyne is evaluated according to relevant specifications. The additional dynamic stress of the foundation is obtained by measuring the vibration velocity of the pile foundation soil by a velocity sensor, thereby evaluating the dynamic stability of the groyne pile foundation system.

[0070] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An experimental apparatus for studying the service performance of piled groynes under tidal load, characterized in that, include: The model box has an opening at the top, and polypropylene foam boards are arranged on the four internal side walls and the bottom to reduce the boundary effect of the model box; the model box is filled with soil, and the soil fills the entire model box. The test model is located above the model box, with its lower end buried in the middle of the soil. The burial depth of the test model is 2 / 3 to 7 / 9 of the length of the groyne pile. The test model is supported above the model box by a clamping assembly. The clamping assembly includes a transversely arranged support and vertical fixed supports fixedly connected to both ends of the transverse support. A slide rail is fixed on the transverse support, and a slider is provided on the test model. The slide rail and the slider cooperate to simulate the sliding support constraint conditions of the pile groyne. A force hammer loading device is provided on the transverse support. The test model is struck by the force hammer loading device, and the test model generates a corresponding dynamic response. The generated internal forces are collected by a data dynamic acquisition instrument.

2. The experimental apparatus for studying the service performance of piled groynes under tidal load as described in claim 1, characterized in that, Strain gauges are arranged on the test model, and the strain gauges are connected to the data acquisition instrument via wires.

3. The experimental apparatus for studying the service performance of piled groynes under tidal load as described in claim 1, characterized in that, One end of the slider is connected to the test model via an additional wing plate, and the slide rail is connected to the transverse support by bolts.

4. The experimental apparatus for studying the service performance of piled groynes under tidal load as described in claim 1, characterized in that, An optical displacement sensor is installed on the vertical fixed support. The optical displacement sensor is facing the horizontal direction of the connecting beam of the test model and is connected to the signal of the data dynamic acquisition instrument.

5. The experimental apparatus for studying the service performance of piled groynes under tidal load as described in claim 1, characterized in that, A velocity sensor is installed on the upper surface of the soil material, and the velocity sensor is connected to the data dynamic acquisition instrument.

6. The experimental apparatus for studying the service performance of piled groynes under tidal load as described in claim 1, characterized in that, The soil material is dry soil, which is filled and compacted in layers, and the density of the soil material is between the maximum density and the minimum density.

7. An experimental apparatus for studying the service performance of piled groynes under tidal loads as described in any one of claims 1 to 6, characterized in that, The method for calculating the bending moment at the strain gauge on the cross section is as follows: The tensile strain ε was obtained through experiments. s ε compressive strain c Assuming that each plane section perpendicular to the axis of the rod remains a plane after deformation under tension, compression, or pure bending, and is perpendicular to the deformed axis of the rod, the experimental model satisfies the plane section assumption. Therefore, the neutral axis and the corresponding tensile strain ε can be determined. s The location distance y is: Where h is the width of the pile along the loading direction; The curvature ρ of the neutral axis can be obtained as: The experimental model material was 6061 aluminum alloy. When the material was within the linear elastic range, according to Hooke's Law, we have: s s =Ee s Where: E is the elastic modulus of the material, σ s This represents the tensile stress corresponding to the location of the tensile strain. From the statics relationship, the bending moment M at the corresponding location can be obtained as: Where: I is the moment of inertia, and A is the cross-sectional area.

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