Degradable plastic drainage plate degradability testing system and method based on CT scanning

Abstract

The invention discloses a degradable plastic drainage plate degradability test system and method based on CT scanning, and the method comprises the steps: placing a container filled with a soil sample and a degradable plastic drainage plate sample in a constant-temperature and constant-humidity environment for degradation culture; at a preset time point, the whole container is placed on a rotating table of a CT scanning imaging unit, 360-degree rotating scanning is carried out, and RAW projection data are obtained; rebuilding the RAW projection data into three-dimensional grayscale image data; then based on the CT value difference, soil, water, a container body, a plastic drainage plate positioning support and a filter membrane are cut off from the three-dimensional grayscale image data, only the plastic phase of the core plate of the degradable plastic drainage plate sample is reserved, and the plastic phase of the core plate is extracted; and finally, calculating the volume of the extracted plastic phase of the core plate at each time point, and calculating the volume degradation rate of the core plate of the degradable plastic drainage plate sample according to the volume.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering and materials engineering testing technology, and specifically relates to a degradation test system and method for biodegradable plastic drainage boards based on CT scanning. Background Technology

[0002] Biodegradable plastic drainage boards are widely used in soft soil foundation treatment projects. However, their gradual degradation in the soil leads to a decline in drainage performance, affecting the long-term stability of the project. Currently, the performance evaluation of this type of drainage board mainly relies on destructive sampling and laboratory physicochemical testing, which has the following significant drawbacks.

[0003] 1. Highly destructive: The drainage board needs to be removed from the soil, disrupting its contact with the surrounding soil and making continuous, in-situ observation impossible.

[0004] 2. Lack of three-dimensional visualization methods: It is impossible to obtain the three-dimensional morphological evolution process of the core board inside the drainage board (the drainage board is composed of an inner core board and a filter membrane covering the core board) in the soil without damage.

[0005] Therefore, there is an urgent need for a technical solution that can visualize and quantitatively evaluate the degradation process and structural damage of the core board of biodegradable drainage boards without disturbing the sample and maintaining the real soil environment. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a CT scan-based degradation testing system and method for biodegradable plastic drainage boards.

[0007] This invention is achieved through the following technical solution: A CT scan-based degradation testing system for biodegradable plastic drainage boards includes: Container: Made of non-metallic materials, the container has a sealed structure and is used to hold soil samples and biodegradable plastic drainage board samples; Plastic drainage board positioning bracket: set at the bottom of the container, used to position and install the biodegradable plastic drainage board sample to be tested, so that the sample is vertically positioned in the middle of the container. CT scanning imaging unit: used to perform 360° rotating scanning of containers containing biodegradable plastic drainage board samples and soil samples to acquire projection data; Image processing and analysis unit: used to reconstruct the projection data acquired by the CT scan imaging unit into three-dimensional grayscale image data, and to segment the reconstructed three-dimensional grayscale image data to segment out the core phase of the biodegradable plastic drainage board sample, extract the three-dimensional voxels of the core phase, calculate its volume at each time point, and calculate the core volume degradation rate of the biodegradable plastic drainage board sample accordingly.

[0008] In the above technical solution, the container material is PMMA (polymethyl methacrylate).

[0009] In the above technical solution, the positioning bracket for the plastic drainage board is made of PMMA (polymethyl methacrylate).

[0010] In the above technical solution, the container is cylindrical, with a detachable top cover. The top cover is connected to the flange on the top of the container by bolts, and a sealing ring is provided between the flange and the top cover to ensure the container's airtightness.

[0011] In the above technical solution, the plastic drainage board positioning bracket is a long strip structure with a slot, which is fixedly installed in the middle of the bottom plate of the container. The bottom end of the biodegradable plastic drainage board sample to be tested is inserted into the slot of the plastic drainage board positioning bracket, and the container is filled with prepared soil sample so that the biodegradable plastic drainage board sample is in a vertical state and the biodegradable plastic drainage board sample is completely buried by soil sample.

[0012] The testing method of the CT scan-based biodegradability testing system for biodegradable plastic drainage boards of the present invention includes the following steps: Step 1: Place the container containing the soil sample and the biodegradable plastic drainage board sample in a constant temperature and humidity environment for degradation culture; Step 2: At the predetermined time point, place the entire container on the rotating stage of the CT scanning imaging unit and perform a 360-degree rotation scan to obtain RAW projection data; Step 3: Reconstruct the RAW projection data into 3D grayscale image data; Step 4: Based on the CT value difference, the soil, water, container body, plastic drainage board positioning bracket and filter membrane are cropped from the three-dimensional grayscale image data, and only the plastic phase of the core board of the biodegradable plastic drainage board sample is retained, so as to extract the plastic phase of the core board. Step 5: Calculate the volume of the extracted core board plastic phase at each time point, and calculate the core board volume degradation rate of the biodegradable plastic drainage board sample accordingly.

[0013] The advantages and beneficial effects of this invention are as follows: This invention enables in-situ non-destructive monitoring: the sample does not need to be removed throughout the entire process, maintaining the true soil-plate contact state and achieving continuous observation throughout the entire life cycle.

[0014] This invention achieves three-dimensional visualization and precise quantification: through CT three-dimensional reconstruction, the structural changes of the core board inside the plastic drainage board can be presented intuitively, and its degradation rate can be quantitatively calculated.

[0015] This invention designs a special container to ensure imaging quality: it uses a low X-ray attenuation material (preferably PMMA material) and optimizes the wall thickness and structure to minimize scanning artifacts and ensure clear images and reliable data. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the test container of the present invention.

[0017] Figure 2 This is a flowchart of a CT scan-based test method for the degradation of biodegradable plastic drainage boards.

[0018] In the figure: 1-Container, 2-Top cover, 3-Bolt, 4-Plastic drainage board positioning bracket, 5-Biodegradable plastic drainage board sample, 6-Sealing ring, 101-Flange.

[0019] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below with reference to specific embodiments.

[0021] This invention provides a CT scan-based degradation testing system for biodegradable plastic drainage boards, comprising: Container: Made of a non-metallic material (e.g., PMMA, polymethyl methacrylate) with low X-ray attenuation, high light transmittance, and mechanical strength meeting earth pressure requirements. The container is a sealed structure capable of maintaining a high moisture content soil environment internally for extended periods. Further details can be found in the appendix. Figure 1 Preferably, the container 1 is cylindrical, and a detachable top cover 2 is provided on its top. The top cover 2 is connected to the flange 101 on the top of the container 1 by bolts 3 (bolts 3 are made of nylon material), and a sealing ring 6 is provided between the flange 101 and the top cover 2 to ensure the sealing of the container 1.

[0022] Plastic drainage board positioning bracket: Located at the bottom of the container, it is used to position and install the biodegradable plastic drainage board sample to be tested, ensuring that the sample is vertically positioned in the center of the container (ensuring that the sample does not contact the inner wall of the container, so that the area around the sample is completely buried by soil). For further details, see the appendix. Figure 1 Preferably, the plastic drainage board positioning bracket 4 is a long strip structure with a slot, which is fixedly installed in the middle of the bottom plate of the container 1. The bottom end of the biodegradable plastic drainage board sample 5 to be tested is inserted into the slot of the plastic drainage board positioning bracket 4, and the container 1 is filled with prepared soil sample so that the biodegradable plastic drainage board sample 5 is in a vertical state and the biodegradable plastic drainage board sample 5 is completely buried by soil sample.

[0023] CT scanning imaging unit: used to perform 360° rotating scanning of containers containing biodegradable plastic drainage board samples and soil samples to acquire projection data.

[0024] Image processing and analysis unit: used to reconstruct the projection data acquired by the CT scan imaging unit into three-dimensional grayscale image data, and to segment the reconstructed three-dimensional grayscale image data to segment out the core phase (plastic phase) of the biodegradable plastic drainage board sample, extract the three-dimensional voxels of the core phase, calculate its volume at each time point, and calculate the core volume degradation rate of the biodegradable plastic drainage board sample accordingly.

[0025] The test method of the CT scan-based biodegradability testing system for biodegradable plastic drainage boards of the present invention is described in the appendix. Figure 2 This includes the following steps: Step 1: Place the container containing the soil sample and the biodegradable plastic drainage board sample in a constant temperature and humidity environment for degradation culture; Step 2: At the predetermined time point, place the entire container on the rotating stage of the CT scanning imaging unit and perform a 360-degree rotation scan to obtain RAW projection data; Step 3: Reconstruct the RAW projection data into 3D grayscale image data; Step 4: Based on the CT value difference, the soil, water, container body, plastic drainage board positioning bracket and filter membrane are cropped from the three-dimensional grayscale image data, and only the plastic phase of the core board of the biodegradable plastic drainage board sample is retained, so as to extract the plastic phase of the core board. Step 5: Calculate the volume of the extracted core board plastic phase at each time point, and calculate the core board volume degradation rate of the biodegradable plastic drainage board sample accordingly.

[0026] Below is a specific example.

[0027] Step 1: Equipment Preparation Prepare a cylindrical PMMA (polymethyl methacrylate) container with an inner diameter of 130 mm and a height of 200 mm. The container wall thickness is 5 mm. The top of the container is equipped with a PMMA cap and a sealing ring.

[0028] Step 2: Soil and Sample Preparation Prepare high-moisture-content silt soil samples, with the moisture content controlled between 80% and 100%, to simulate actual soft soil conditions.

[0029] A biodegradable plastic drainage board sample with dimensions of 4mm×100mm×200mm was prepared and vertically fixed in the center of the container using a plastic drainage board positioning bracket 4.

[0030] The soil sample was filled in layers and gently vibrated to remove large air bubbles, ensuring close contact between the soil sample and the biodegradable plastic drainage board sample.

[0031] Cover with the sealing ring and top cover and tighten (using nylon bolts) to form a sealed system.

[0032] Step 3: CT Scan and Data Acquisition (1) Place the container containing the soil sample and the test sample in a constant temperature and humidity environment for degradation culture.

[0033] (2) At predetermined time points (e.g., 0, 30, 60, 90 days), place the entire container on the rotating stage of the CT scanning imaging unit.

[0034] (3) Set scanning parameters: voltage recommended 120kV-140kV (to penetrate the soil sample), current 200-300μA, integration time 500ms (adjust according to the equipment).

[0035] (4) Perform a 360-degree rotation scan to obtain RAW projection data.

[0036] Step 4: Image Processing and Quantitative Analysis (1) 3D reconstruction: The RAW projection data is reconstructed into 3D grayscale image data using the FDK algorithm.

[0037] (2) Threshold segmentation (cropping): Based on the difference in CT values ​​of different materials, different phases such as soil, water, container body, plastic drainage board positioning bracket, and core plate and filter membrane of biodegradable plastic drainage board sample can be distinguished; soil, water, container body, plastic drainage board positioning bracket and filter membrane are cropped from the three-dimensional grayscale image data, and only the plastic phase of the core plate of biodegradable plastic drainage board sample is retained, thereby realizing the extraction of the core plate plastic phase.

[0038] (3) Data calculation: Calculate the volume of the extracted core board plastic phase at each time point, and calculate the core board volume degradation rate of the biodegradable plastic drainage board sample accordingly.

[0039] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A CT scan-based degradation testing system for biodegradable plastic drainage boards, characterized in that, include: Container: Made of non-metallic materials, the container has a sealed structure and is used to hold soil samples and biodegradable plastic drainage board samples; Plastic drainage board positioning bracket: set at the bottom of the container, used to position and install the biodegradable plastic drainage board sample to be tested, so that the sample is vertically positioned in the middle of the container. CT scanning imaging unit: used to perform 360° rotating scanning of containers containing biodegradable plastic drainage board samples and soil samples to acquire projection data; Image processing and analysis unit: used to reconstruct the projection data acquired by the CT scan imaging unit into three-dimensional grayscale image data, and to segment the reconstructed three-dimensional grayscale image data to segment out the core phase of the biodegradable plastic drainage board sample, extract the three-dimensional voxels of the core phase, calculate its volume at each time point, and calculate the core volume degradation rate of the biodegradable plastic drainage board sample accordingly.

2. The degradation testing system for biodegradable plastic drainage boards based on CT scanning according to claim 1, characterized in that: The container is made of PMMA (polymethyl methacrylate).

3. The degradation testing system for biodegradable plastic drainage boards based on CT scanning according to claim 1, characterized in that: The positioning bracket for the plastic drainage board is made of PMMA (polymethyl methacrylate).

4. The degradation testing system for biodegradable plastic drainage boards based on CT scanning according to claim 1, characterized in that: The container is cylindrical with a removable top cover. The top cover is connected to the flange on the top of the container by bolts, and a sealing ring is installed between the flange and the top cover to ensure the container's airtightness.

5. The degradation testing system for biodegradable plastic drainage boards based on CT scanning according to claim 1, characterized in that: The plastic drainage board positioning bracket is a long strip structure with a slot, which is fixedly installed in the middle of the bottom plate of the container. The bottom end of the biodegradable plastic drainage board sample to be tested is inserted into the slot of the plastic drainage board positioning bracket, and the container is filled with the prepared soil sample so that the biodegradable plastic drainage board sample is in a vertical position and the biodegradable plastic drainage board sample is completely buried by the soil sample.

6. The test method of the CT scan-based biodegradability testing system for biodegradable plastic drainage boards according to claim 1, characterized in that: Includes the following steps: Step 1: Place the container containing the soil sample and the biodegradable plastic drainage board sample in a constant temperature and humidity environment for degradation culture; Step 2: At the predetermined time point, place the entire container on the rotating stage of the CT scanning imaging unit and perform a 360-degree rotation scan to obtain RAW projection data; Step 3: Reconstruct the RAW projection data into 3D grayscale image data; Step 4: Based on the CT value difference, the soil, water, container body, plastic drainage board positioning bracket and filter membrane are cropped from the three-dimensional grayscale image data, and only the plastic phase of the core board of the biodegradable plastic drainage board sample is retained, so as to extract the plastic phase of the core board. Step 5: Calculate the volume of the extracted core board plastic phase at each time point, and calculate the core board volume degradation rate of the biodegradable plastic drainage board sample accordingly.

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