Non-contact testing device and method for coarse-grained fillers vibration compaction

Abstract

This invention provides a non-contact testing device and method for coarse-particle packing vibration compaction, relating to the field of geotechnical engineering technology. The device includes a transparent test cylinder apparatus, a compactor, and a monitoring device. The transparent test cylinder apparatus comprises a base plate, a pad plate, and a cylinder body connected in sequence. The base plate is fixedly mounted on a workbench, and the cylinder body is mounted on the base plate. The cylinder body has a hollow cylindrical structure and is filled with a transparent soil sample. The cylinder wall includes transparent and non-transparent areas. The pad plate is positioned between the base plate and the cylinder body. The compactor is positioned above the cylinder body, with its hammering direction pointing towards the center of the compaction cylinder. The monitoring device measures through the transparent area of ​​the cylinder towards the transparent soil sample. The monitoring device includes a binocular industrial camera and an infrared moisture meter. The compactor-cylinder apparatus proposed in this invention effectively solves the problem that traditional test cylinders cannot observe the particle size distribution reorganization and pore structure evolution processes during compaction.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, and more specifically, to a non-contact testing device and method for coarse-particle packing vibration compaction. Background Technology

[0002] Vibration compaction testing of coarse-grained fill is a core technical means for controlling the quality of fill in highway subgrade engineering. It simulates the vibration conditions of a road roller in the field and determines the maximum dry density and optimum moisture content of the fill material indoors, providing crucial data for on-site compaction control. This test directly relates to the bearing capacity, settlement stability, and long-term durability of the subgrade, making it an indispensable quality control link in highway construction. However, existing testing methods have many shortcomings: First, existing methods require destroying the sample to measure density (such as the drying method or ring cutter method), resulting in unusable samples and the inability to monitor in real time; second, existing methods only provide single-point or local dry density values, failing to observe particle size distribution reorganization and pore structure evolution; furthermore, existing methods do not quantitatively assess the uniformity of fill material mixing, relying on subjective visual observation, leading to strong dispersion in sampling test results. Therefore, extensive orthogonal experiments are necessary to fit and reduce errors. These limitations severely restrict testing efficiency and data reliability.

[0003] Based on the shortcomings of the existing technology, there is an urgent need for a non-contact testing device and method for vibration compaction of coarse particle packing. Summary of the Invention

[0004] The purpose of this invention is to provide a non-contact testing device and preparation method for coarse particle packing vibration compaction, in order to improve the above-mentioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows:

[0005] In a first aspect, this application provides a non-contact testing device for the vibration compaction of coarse-particle fillers, comprising: a transparent test cylinder device, a compactor, and a monitoring device; the transparent test cylinder device includes a base plate, a pad plate, and a cylinder body connected in sequence; the base plate is fixedly mounted on a workbench; the cylinder body is mounted on the base plate; the cylinder body has a hollow cylindrical structure; the cylinder body is filled with a transparent soil sample; the cylinder wall includes a transparent area and a non-transparent area; the pad plate is positioned between the base plate and the cylinder body; the compactor is positioned above the cylinder body; the compactor's hammering direction is towards the center of the cylinder body; the monitoring device's measurement direction is through the transparent area of ​​the cylinder body towards the transparent soil sample; the monitoring device includes a binocular industrial camera and an infrared moisture meter.

[0006] Furthermore, the cylinder includes a sleeve, a compaction cylinder, and black cardboard. The two ends of the compaction cylinder are fixedly connected to the sleeve and the pad, respectively. The sleeve and the compaction cylinder form a hollow cylindrical structure. The compaction cylinder is transparent. The black cardboard is fixedly disposed on the back side of the inner wall of the compaction cylinder.

[0007] Furthermore, the base plate is a steel structure, and the base plate is fixedly mounted on the workbench by bolts.

[0008] Furthermore, the sleeve is made of transparent acrylic sheet material.

[0009] Furthermore, the transparent soil sample is made by mixing fused silica sand with a refractive index-matching liquid.

[0010] Secondly, this application provides a non-contact test method for vibration compaction of coarse-particle packing, including:

[0011] Prepare transparent soil samples with a preset moisture content and perform impregnation treatment;

[0012] The cylinder is treated to prevent sticking and then filled with the transparent soil sample in layers;

[0013] A binocular camera and an infrared moisture meter are set up, and the mapping relationship between image data and the spatial coordinates of the cylinder is established through three-dimensional calibration;

[0014] The compaction device is activated to hammer the transparent soil sample, and binocular image data and infrared spectral data of the soil sample inside the cylinder are collected simultaneously.

[0015] Based on the mapping relationship described in the steps, a three-dimensional displacement field calculation is performed on the binocular image data, and the water content is inverted by combining the infrared spectral data to calculate the compaction and non-uniformity data of the transparent soil sample.

[0016] Based on the comparison results of the non-uniformity data and the compaction data with the preset threshold, the termination of the compaction process is dynamically controlled.

[0017] The beneficial effects of this invention are as follows:

[0018] The compaction test tube device proposed in this invention can effectively solve the problem that traditional test tubes cannot observe the particle gradation reorganization and pore structure evolution process during compaction. The method provided by this invention is based on three-dimensional calibration mapping and displacement field analysis technology, which realizes full-field, non-destructive, real-time calculation and monitoring of dry density, compaction degree and non-uniformity during compaction. It replaces the traditional method of relying on destructive sampling to obtain single-point discrete data, reconstructs the testing logic of coarse particle filler, and significantly improves the efficiency and practicality of coarse particle filler compaction test. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the non-contact test device for vibration compaction of coarse particle packing.

[0021] Figure 2 for Figure 1 Top view;

[0022] Figure 3 This is a flowchart of the non-contact test method for vibration compaction of coarse particle packing.

[0023] The markings in the diagram are: 1. Transparent test tube device; 11. Base plate; 12. Pad plate; 13. Cylinder body; 131. Sleeve; 132. Compaction cylinder; 133. Black cardboard; 2. Compaction instrument; 3. Monitoring device; 4. Transparent soil sample. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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 some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] Example 1:

[0027] like Figure 1 and Figure 2As shown, this embodiment provides a non-contact testing device for the vibration compaction of coarse-particle fillers. It includes a transparent test cylinder device 1, a compactor 2, and a monitoring device 3. The transparent test cylinder device 1 comprises a base plate 11, a pad plate 12, and a cylinder 13, which are sequentially fixedly connected. The base plate 11 is fixedly mounted on a workbench, serving as the stable foundation for the entire device. The cylinder 13 is mounted on the base plate 11 and has a hollow cylindrical structure. The cylinder 13 is filled with a transparent soil sample 4. The cylinder wall includes transparent and non-transparent areas. The transparent areas allow the optical equipment and infrared light of the monitoring device 3 to penetrate, enabling observation and measurement of the sample inside the cylinder. The non-transparent areas are used to block stray light and provide necessary observation windows. The pad plate 12 is positioned between the base plate 11 and the cylinder 13, acting as a buffer. The compactor 2 is positioned above the cylinder 13 to simulate the vibration compaction process. The compactor 2 is pounded towards the center of the cylinder 13, ensuring that the load is applied perpendicularly to the center of the filler, simulating a more uniform compaction process; the monitoring device 3 is measured through the transparent area of ​​the cylinder 13 towards the transparent soil sample 4, and the monitoring device 3 includes a binocular industrial camera and an infrared moisture meter.

[0028] Preferably, such as Figure 1 and Figure 2 As shown, the cylinder 13 includes a sleeve 131, a compaction cylinder 132, and a black cardboard 133. The two ends of the compaction cylinder 132 are fixedly connected to the sleeve 131 and the pad 12, respectively. The sleeve 131 is used to fix the compaction cylinder 132, provide support during the test, prevent the compaction cylinder 132 from moving or deforming, and provide sufficient compacted soil sample for the compaction cylinder 132. The sleeve 131 and the compaction cylinder 132 form a hollow cylindrical structure. The compaction cylinder 132 is transparent, and the black cardboard 133 is fixedly installed on the back side of the inner wall of the compaction cylinder 132, forming a sharp visual contrast with the transparent soil.

[0029] Preferably, the base plate 11 is a steel structure, and the base plate 11 is fixedly mounted on the workbench by bolts. This provides stable support for the upper structure of the transparent test tube device 1.

[0030] Preferably, the sleeve 131 is made of transparent acrylic sheet material.

[0031] Preferably, the transparent soil sample 4 is made by mixing fused silica sand with a refractive index-matching liquid.

[0032] Example 2:

[0033] Corresponding to the above embodiment of the non-contact test device for vibration compaction of coarse particle packing, this embodiment provides a non-contact test method for vibration compaction of coarse particle packing, such as... Figure 3 As shown, steps S100 to S600 are included:

[0034] Step S100: Prepare a transparent soil sample with a preset moisture content and perform an impregnation treatment;

[0035] Specifically, the transparent soil sample is sieved and dried at high temperature. Then, pure water is added according to the preset moisture content conditions. After stirring evenly, the soil sample and container are wrapped with plastic wrap and soaked for more than 6 hours.

[0036] Step S200: Perform anti-sticking treatment on the cylinder and fill it with transparent soil sample in layers;

[0037] Specifically, a layer of Vaseline is applied inside the cylinder, and a plastic film is placed on the pad. Soil samples are then added using the three-layer method.

[0038] Step S300: Set up a binocular camera and an infrared moisture meter, and establish a mapping relationship between image data and cylinder spatial coordinates through three-dimensional calibration;

[0039] Understandably, in this step, the binocular industrial camera and infrared moisture meter are fixed to the front side of the cylinder, and the power and signal cables are connected to the computer to perform three-dimensional calibration and spatial reconstruction of the binocular camera.

[0040] Further, step S300 includes steps S310 to S330:

[0041] Step S310: Fix the binocular industrial camera and infrared moisture meter to the front side of the cylinder, and adjust the focal length and the incident angle of the light source.

[0042] Step S320: Based on the images acquired by the binocular industrial camera, solve for the camera intrinsic parameter matrix and extrinsic parameter matrix using the Zhang Youzheng calibration method;

[0043] Step S330: Construct a projection matrix based on the intrinsic parameter matrix and extrinsic parameter matrix, and establish a mapping relationship between pixel coordinates and three-dimensional spatial coordinates of the cylinder.

[0044] Understandably, the first step is to define the area of ​​the cylinder as the region of interest (ROI). During the calibration of the stereo camera, the Zhang Youzheng calibration method is used to determine the camera's intrinsic and extrinsic parameters, establishing a mapping relationship between pixel coordinates and 3D spatial coordinates.

[0045] ;

[0046] in, As a scale factor, Image pixel coordinates, As a world coordinate system, The intrinsic parameter matrix of the camera (including focal length) , Main point , ), , Here are the extrinsic parameter matrices (rotation matrix and translation vector). The above binocular camera calibration is used to ensure the accuracy of displacement and strain measurements.

[0047] Step S400: Start the compactor to hammer the transparent soil sample, and simultaneously collect binocular image data and infrared spectral data of the soil sample inside the cylinder;

[0048] Step S500: Based on the mapping relationship, perform three-dimensional displacement field calculation on the binocular image data, and combine the infrared spectral data to invert the water content, and calculate the compaction and non-uniformity data of the transparent soil sample.

[0049] Further, step S500 includes steps S510 to S530;

[0050] Step S510: Based on the mapping relationship, perform grid matching and spatial coordinate transformation on the binocular image data to generate three-dimensional displacement field data of the soil sample inside the cylinder;

[0051] Step S520: Based on the infrared spectral data, the real-time moisture content of the soil sample is obtained by inversion using a preset absorbance-moisture content mathematical model;

[0052] Step S530: Based on the three-dimensional displacement field data and real-time moisture content, calculate the compaction degree data and non-uniformity data of the soil sample;

[0053] The specific calculation process is as follows:

[0054] Based on the selected region of interest, it is divided into There are 10 grids, and each grid is matched using a cross-correlation function:

[0055] ;

[0056] in, Indicates the degree of matching. For a reference image (calculating the grayscale value of a grid cell in the previous frame of the image), The average gray value of all grids in the reference image; The grayscale value of the search grid in the calculated image. To calculate the average gray value of all grid cells in the image. When At its maximum, grid matching is successful. Based on this, all grids in the reference image and the computed image can be matched.

[0057] Furthermore, using calibration parameters, the pixel coordinates of the mesh matching are converted into three-dimensional spatial coordinates:

[0058] ;

[0059] in, , These are the projection matrices for the left and right cameras, respectively. and These are the projection matrices for the left and right cameras, respectively.

[0060] ;

[0061] in, Given the camera's projection matrix; solve the overdetermined system of equations to obtain the 3D point coordinates of the image. :

[0062] ;

[0063] in, , , Represents three-dimensional spatial coordinates; This represents the transpose of a matrix.

[0064] Based on this, the displacement vector of each grid is obtained:

[0065] ;

[0066] in, This represents the displacement vector for each grid cell; and These are the three-dimensional coordinates of the computed image and the reference image at the center of the grid, respectively.

[0067] According to the Green-Lagrange strain tensor:

[0068] ;

[0069] in, For strain tensor, , Corresponding to three normal strains and three shear strains .

[0070] Next, for the displacement vector Perform spatial differentiation:

[0071] ;

[0072] in, For the first i Displacement vectors of each grid; These are the coordinates of the corresponding three-dimensional point; Let be the coordinate change. Substituting this into the strain formula, we obtain the strain tensor of the mesh:

[0073] ;

[0074] in, Let represent the total strain tensor of the mesh. Then, the _i_th Volumetric strain of a grid under a single hammer blow It can be represented as:

[0075] ;

[0076] This yielded the average strain across the entire field of the soil sample inside the cylinder after a single impact. It can be represented as:

[0077] ;

[0078] Under the impact of compaction It is usually a negative value.

[0079] Based on the above formula, the overall strain value inside the cylinder under one impact was obtained. This increases the accuracy of the indoor compaction test, making the test results more stable and reliable.

[0080] Further, step S530 includes steps S531 to S533:

[0081] Step S531: Based on the volumetric strain in the three-dimensional displacement field data, perform wet density recursive update processing based on the strain-density conversion model under the volume compression relationship to obtain real-time wet density data.

[0082] Step S532: Based on the real-time wet density data and moisture content data, perform dry density conversion processing to obtain the real-time dry density data of the soil sample;

[0083] Step S533: Based on the dry density data and wet density spatial distribution data, perform engineering parameter calculation and processing. Through maximum dry density ratio analysis and density field statistical analysis, obtain the compaction degree data and non-uniformity data of the soil sample.

[0084] It should be noted that the initial density of the soil inside the cylinder is assumed to be... (Measured before the experiment), mass is The volume of the cylinder is The wet density of the soil sample inside the cylinder after the first hammer blow. It can be represented as:

[0085] ;

[0086] in, This represents the volumetric strain under the first impact of the hammer.

[0087] In the After the second hammer blow, the mass of the soil sample inside the cylinder was: , In the first The soil density inside the cylinder after one hammer blow; the relationship between wet density and the number of hammer blows can be expressed as:

[0088] ;

[0089] The derived formula can be used to calculate the wet density of transparent soil samples inside the cylinder in real time, without the need for repeated sampling and measurement. Furthermore, wet density is a key parameter for calculating the compaction degree of the fill material.

[0090] Based on the relationship between wet density and the number of hammer blows, the dry density and compaction degree of transparent soil filler can be calculated in real time.

[0091] Specifically, the overall moisture content of the soil sample inside the cylinder is calculated based on the spectral data monitored by the infrared moisture meter:

[0092] ;

[0093] in, Moisture content, Absorbance and The calibration coefficients can be obtained by least squares fitting.

[0094] Then in the The dry density of the soil sample inside the cylinder after the second hammer blow It can be represented as:

[0095] ;

[0096] in, Indicates the first i Moisture content after the second hammer blow; based on this, in the first... After the second hammer blow, the compaction degree of the filling soil sample inside the cylinder. It can be represented as:

[0097] ;

[0098] in, This represents the maximum dry density of the fill soil sample.

[0099] Furthermore, since excessively high non-uniformity of the density field of transparent soil filler can cause significant dispersion in the overall results of compaction tests, this invention provides a compaction index and a corresponding calculation method.

[0100] The inhomogeneity of the density field can be characterized using statistical methods:

[0101] ;

[0102] ;

[0103] in, for The standard deviation of the density of each grid cell For the first The density of each grid, for Average density of each grid, The coefficient of variation is used as a measure of inhomogeneity. This method upgrades empirical judgment to objective statistics by introducing the coefficient of variation of the density field as a quantitative indicator of inhomogeneity.

[0104] Further, step S600 includes steps S610 to S630:

[0105] Step S600: Based on the comparison results of the non-uniformity data and compaction data with the preset threshold, dynamically control the termination of the compaction process.

[0106] Step S610: Obtain the non-uniformity data and compaction data under the current number of compaction passes;

[0107] Step S620: Determine whether the non-uniformity data exceeds the preset non-uniformity threshold, or whether the compaction data reaches the compaction threshold required by the project.

[0108] Step S630: If the non-uniformity data exceeds the threshold or the compaction data reaches the threshold, send a termination command to the compactor to stop the compaction process.

[0109] Specifically, the criteria for judging compaction degree are as follows:

[0110] like If so, continue testing;

[0111] like If so, then stop the test;

[0112] in, The required compaction degree is the threshold for the engineering project; higher compaction degrees will increase unnecessary construction costs.

[0113] like If so, continue testing;

[0114] like If so, then stop the test;

[0115] in, The non-uniformity threshold required for the engineering project can be set by the user according to the specific soil particle size distribution.

[0116] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A non-contact test method for vibration compaction of coarse-particle packing, comprising a non-contact test device for vibration compaction of coarse-particle packing, characterized in that, The non-contact testing device for coarse particle packing vibration compaction includes: A transparent test tube device (1) includes a base plate (11), a pad plate (12), and a cylinder (13) that are fixedly connected in sequence. The base plate (11) is fixedly set on the workbench, and the cylinder (13) is set on the base plate (11). The cylinder (13) is a hollow cylindrical structure. The cylinder (13) is filled with a transparent soil sample (4). The cylinder wall of the cylinder (13) includes a transparent area and a non-transparent area. The pad plate (12) is set between the base plate (11) and the cylinder (13). A compaction device (2) is disposed above the cylinder (13), and the compaction device (2) is pounded in the direction of the center of the cylinder (13). The monitoring device (3) is directed through the transparent area of ​​the cylinder (13) toward the transparent soil sample (4). The monitoring device (3) includes a binocular industrial camera and an infrared moisture meter. The non-contact test method for coarse particle packing vibration compaction includes: Prepare a transparent soil sample with a preset moisture content (4) and perform a soaking treatment; The cylinder (13) was treated to prevent sticking and then filled with the transparent soil sample (4) in layers; A binocular camera and an infrared moisture meter were set up, and the mapping relationship between image data and the spatial coordinates of the cylinder (13) was established through three-dimensional calibration. Start the compaction device (2) to hammer the transparent soil sample (4), and simultaneously collect binocular image data and infrared spectral data of the soil sample inside the cylinder (13); Based on the mapping relationship, the three-dimensional displacement field of the binocular image data is calculated, and the water content is inverted by combining the infrared spectral data to calculate the compaction and non-uniformity data of the transparent soil sample (4). Based on the comparison results between the non-uniformity data and the compaction data and the preset threshold, the termination of the compaction process is dynamically controlled. The setup includes a binocular camera and an infrared moisture meter. A mapping relationship between image data and the spatial coordinates of the cylinder (13) is established through three-dimensional calibration, including: Fix the binocular industrial camera and infrared moisture meter to the front side of the cylinder (13), and adjust the focal length and the incident angle of the light source; Based on the images acquired by the binocular industrial camera, the camera intrinsic parameter matrix and extrinsic parameter matrix are solved using the Zhang Youzheng calibration method. Based on the intrinsic parameter matrix and the extrinsic parameter matrix, a projection matrix is ​​constructed to establish the mapping relationship between pixel coordinates and the three-dimensional spatial coordinates of the cylinder (13); Specifically, based on the mapping relationship, a three-dimensional displacement field is calculated on the binocular image data, and the water content is inverted using infrared spectral data to calculate the compaction and heterogeneity data of the transparent soil sample (4), including: Based on the mapping relationship, the binocular image data is subjected to grid matching and spatial coordinate transformation to generate three-dimensional displacement field data of the soil sample inside the cylinder (13); Based on the infrared spectral data, the real-time moisture content of the soil sample is obtained by inversion using a preset absorbance-moisture content mathematical model; Based on the three-dimensional displacement field data and the real-time moisture content, the compaction degree data and non-uniformity data of the soil sample are calculated.

2. The non-contact test method for coarse particle packing vibration compaction according to claim 1, characterized in that: The cylinder (13) includes a sleeve (131), a compaction cylinder (132), and a black cardboard (133). The two ends of the compaction cylinder (132) are fixedly connected to the sleeve (131) and the pad (12), respectively. The sleeve (131) and the compaction cylinder (132) form a hollow cylindrical structure. The compaction cylinder (132) is transparent. The black cardboard (133) is fixedly disposed on the back side of the inner wall of the compaction cylinder (132).

3. The non-contact test method for coarse particle packing vibration compaction according to claim 1, characterized in that: The base plate (11) is a steel structure and is fixed on the workbench by bolts.

4. The non-contact test method for coarse particle packing vibration compaction according to claim 2, characterized in that: The sleeve (131) is made of transparent acrylic sheet material.

5. The non-contact test method for coarse particle packing vibration compaction according to claim 1, characterized in that: The transparent soil sample (4) was made by mixing fused silica sand with a refractive index matching liquid.

6. The non-contact test method for vibration compaction of coarse particle packing according to claim 1, characterized in that, Based on the mapping relationship described in the steps, and using the three-dimensional displacement field data and the real-time moisture content, the compaction degree data and non-uniformity data of the soil sample are calculated, including: Based on the volumetric strain in the three-dimensional displacement field data, the wet density is recursively updated using a strain-density conversion model under the volumetric compression relationship to obtain real-time wet density data. Based on the real-time wet density data and the moisture content data, a dry density conversion process is performed to obtain the real-time dry density data of the soil sample. Based on the dry density data and the spatial distribution data of wet density, engineering parameters are calculated and processed. Through maximum dry density ratio analysis and density field statistical analysis, the compaction degree data and non-uniformity data of the soil sample are obtained.

7. The non-contact test method for coarse particle packing vibration compaction according to claim 1, characterized in that, Based on the comparison results of the non-uniformity data and the compaction degree data with the preset threshold, the termination of the compaction process is dynamically controlled, including: Obtain the non-uniformity data and compaction degree data under the current compaction number; Determine whether the non-uniformity data exceeds a preset non-uniformity threshold, or whether the compaction data reaches the compaction threshold required by the project. If the unevenness data exceeds the threshold or the compaction data reaches the threshold, a termination command is sent to the compactor (2) to stop the compaction process.

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