A coarse-grained saline soil subsidence testing device with resistivity imaging

Abstract

The utility model discloses a kind of coarse particle saline soil dissolution testing devices of resistivity imaging, shaft pressure mechanism is installed on counterforce frame, base is fixed on shaft pressure mechanism, upper cover is connected with base by connecting mechanism, so that upper cover, soil sample barrel and base are pressed tightly fixed;Head mechanism is in the inside of soil sample barrel;When shaft pressure mechanism drives base and soil sample barrel to move upwards, head mechanism remains stationary, realize to coarse particle saline soil to exert stress;Displacement measuring device is installed on upper cover, for measuring the stress deformation condition of coarse particle saline soil in the process of exerting;Water source is used to inject water flow into soil sample barrel to carry out dissolution testing;Resistivity testing system includes resistivity testing device and electrode, electrode is contacted with coarse particle saline soil in soil sample barrel, the potential data of electrode in dissolution testing process is obtained by resistivity testing device, for subsequent imaging inside coarse particle saline soil, realize to the analysis of sample inside salt water interaction and water salt migration in dissolution process.

Description

Technical Field

[0001] This utility model belongs to the field of indoor geotechnical testing, specifically relating to a testing device for the dissolution of coarse-grained saline soil with resistivity imaging. Background Technology

[0002] Coarse-grained saline soil is widely distributed in Northwest my country. Due to its solubility and collapse characteristics, coarse-grained saline soil foundations often pose safety hazards and risks to engineering structures. The essence of the solubility and collapse characteristics of coarse-grained saline soil is that it contains a large amount of soluble salts. In the dry state, the salt crystallizes and has a cementing effect. When it comes into contact with water, the salt dissolves rapidly, reducing the soil strength and causing deformation. Therefore, it is necessary to study the solubility and collapse characteristics of coarse-grained saline soil.

[0003] Currently, there are many devices used for dissolution experiments on coarse-grained saline soils. These devices typically employ methods such as placing a displacement sensor or dial gauge at the top of the sample to measure the overall deformation of the sample during the experiment and calculate the dissolution coefficient. However, these existing methods can only measure the macroscopic deformation of the sample and cannot study the interaction between saline solution and water-salt migration within the sample during the dissolution process, nor can they reflect the anisotropy of the soil sample structure before and after the experiment. Utility Model Content

[0004] To address the problems existing in the prior art, this utility model provides a coarse-grained saline soil solution collapse testing device with resistivity imaging. By imaging the resistivity of the sample during the solution collapse test, it enables the analysis of the interaction between saline water and the migration of water and salt within the sample during the solution collapse process, and can reflect the anisotropy of the soil sample structure before and after the test.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: a coarse-grained saline soil dissolution test device with resistivity imaging, including a reaction frame, an axial compression mechanism, a base, a soil sample bucket, a top cover, a pressure head mechanism, a displacement measuring device, a pressure water source, and a resistivity testing system. The axial compression mechanism is installed in the middle of the reaction frame, and the base is fixed on the upper part of the pressure end of the axial compression mechanism. The soil sample bucket is a cylindrical shape with open ends placed on the base, used to hold coarse-grained saline soil. The upper cover is placed on the upper part of the soil sample bucket, and the upper cover is connected to the base through a connecting mechanism, so that the upper cover, soil sample bucket and base are pressed and fixed together. The pressure head mechanism is located inside the soil sample container and includes a pressure plate and a pressure rod. One end of the pressure rod is fixedly connected to the center of the pressure plate, and the axis of the pressure rod is perpendicular to the upper surface of the pressure plate. A through hole is opened in the center of the upper cover, and the other end of the pressure rod extends out of the soil sample container from the through hole and is fixedly connected to the support beam on the upper part of the reaction frame. When the axial pressure mechanism drives the base and the soil sample container to move upward, the pressure head mechanism remains stationary, thereby applying stress to the coarse-grained saline soil. A displacement measuring device is installed on the upper cover to measure the stress deformation of the coarse-grained saline soil during the stress application process. The pressure rod has a water-permeable hole at the top and a water inlet hole at the bottom of the pressure plate. The water-permeable hole and the water inlet hole are connected through the water flow channel inside the pressure rod and the pressure plate. The pressure water source is connected to the water-permeable hole and is used to inject water into the soil sample bucket for dissolution testing. The base has a water outlet hole and is used to discharge the water injected for testing from the soil sample bucket. The resistivity testing system includes a resistivity testing device and multiple electrodes. Multiple mounting holes are opened on the side wall of the soil sample bucket, and multiple electrodes are installed in each mounting hole and in contact with the coarse-grained saline soil inside the soil sample bucket. Each electrode is connected to the resistivity testing device. The potential data of each electrode during the solution collapse test is acquired in real time through the resistivity testing device, which is used for subsequent imaging of the interior of the coarse-grained saline soil.

[0006] Furthermore, a groove is formed on the upper surface of the base, and the soil sample bucket is placed in the groove. This limits the position of the soil sample bucket on the upper surface of the base, preventing the soil sample bucket from moving around during pressure application.

[0007] Furthermore, it also includes a collection tank, which is connected to the outlet via a drainage pipe to collect water discharged from the solution collapse test. The drainage pipe is equipped with a drainage control valve to control the connection between the outlet and the collection tank as needed. Collecting water facilitates subsequent testing and effectively conserves water resources.

[0008] Furthermore, the connecting mechanism is a bolt. Using bolts facilitates the installation, fixing, and disassembly of the top cover, soil sample container, and base, and makes it convenient to replace the internal coarse-grained saline soil.

[0009] Furthermore, the displacement measuring device is a dial gauge, which is fixed on the upper surface of the cover. The probe of the dial gauge is in contact with the support beam on the upper part of the reaction frame. When the dial gauge moves upward with the cover, the probe of the dial gauge continuously measures the change in distance between it and the support beam, thereby determining the stress deformation of the coarse-grained saline soil in the soil sample bucket.

[0010] Furthermore, the soil sample container has two rows of mounting holes on its side wall, each row arranged along the axial direction of the container, and the two rows are symmetrically arranged about the axis of the container. This arrangement of the electrodes increases the resistivity acquisition range for coarse-grained saline soil, facilitating subsequent imaging.

[0011] Furthermore, the electrode is sealed to the mounting hole with epoxy resin. This ensures a tight seal between the electrode and the mounting hole, preventing coarse-grained saline soil from leaking out during testing.

[0012] Furthermore, both the soil sample container and the pressure head mechanism are made of polyetheretherketone (PEEK). This material has sufficient rigidity to ensure accurate deformation measurement, as well as insulation to reduce the influence of external boundaries on the test results.

[0013] Furthermore, the resistivity testing device is a network parallel resistivity meter.

[0014] Compared with existing technologies, this utility model combines a reaction frame, an axial compression mechanism, a base, a soil sample container, a top cover, a pressure head mechanism, a displacement measuring device, a pressure water source, and a resistivity testing system, which has the following advantages: 1. This utility model, through the cooperation of a reaction frame, axial compression mechanism, base, soil sample bucket, top cover and pressure head mechanism, can apply different consolidation stresses to coarse-grained saline soil, and monitor its stability stage through a displacement measuring device. This facilitates the solution collapse test to be carried out in different stable consolidation stress environments, providing support for subsequent data analysis.

[0015] 2. This utility model uses a pressurized water source to inject water into coarse-grained saline soil under different consolidation stress conditions to conduct a solution collapse test. During the test, a resistivity testing system is used to continuously acquire potential data at different locations of the coarse-grained saline soil. After the test is completed, the resistivity distribution image of the coarse-grained saline soil under different consolidation pressures can be directly obtained through existing inversion methods. Based on this image, the interaction of brine and water-salt migration inside the sample during the solution collapse process can be analyzed, as well as the anisotropy of the soil sample structure before and after the test can be reflected. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model.

[0017] Figure 2 This is a schematic diagram of the soil sample bucket in this utility model.

[0018] In the diagram: 1. Reaction frame; 2. Axial compression mechanism; 3. Base; 4. Soil sample container; 5. Top cover; 6. Pressure head mechanism; 7. Dial gauge; 8. Pressure water source; 9. Drainage pipe; 10. Collection tank; 11. Resistivity testing system; 12. Water outlet; 13. Electrode; 14. Epoxy resin; 15. Water permeable hole; 16. Drainage control valve. Detailed Implementation

[0019] The present invention will be further described below.

[0020] like Figure 1As shown, this utility model includes a reaction frame 1, an axial compression mechanism 2, a base 3, a soil sample container 4, a top cover 5, a pressure head mechanism 6, a displacement measuring device, a pressure water source 8, and a resistivity testing system 11. The axial compression mechanism 2 is installed in the middle of the reaction frame 1 and is a hydraulic cylinder or a pneumatic cylinder. The base 3 is fixed to the upper part of the pressure end of the axial compression mechanism 2. The soil sample container 4 is a cylindrical shape with open ends, placed on the base, and is used to hold coarse-grained saline soil. The top cover 5 is placed on the top of the soil sample container 4, and the top cover 5 is connected to the base 3 through a connecting mechanism, so that the top cover 5, the soil sample container 4, and the base 3 are pressed and fixed together. The pressure head mechanism 6 is located inside the soil sample container 4 and includes a pressure plate and a pressure rod. One end of the pressure rod is fixedly connected to the center of the pressure plate, and the axis of the pressure rod is perpendicular to the center of the pressure plate. The pressure rod extends from the upper surface of the pressure plate; a through hole is opened in the center of the upper cover 5, and the other end of the pressure rod extends out of the through hole into the soil sample bucket 4, and is fixedly connected to the support beam on the upper part of the reaction frame 1; when the axial pressure mechanism 2 drives the base 3 and the soil sample bucket 4 to move upward, the pressure head mechanism 6 remains stationary, thereby applying stress to the coarse-grained saline soil; a displacement measuring device is installed on the upper cover 5 to measure the stress deformation of the coarse-grained saline soil during the stress application process; a water permeable hole 15 is opened at the upper part of the pressure rod, and a water inlet hole is opened at the lower part of the pressure plate. The water permeable hole 15 and the water inlet hole are connected through the water flow channel inside the pressure rod and the pressure plate. The pressure water source 8 is connected to the water permeable hole 15 to inject water into the soil sample bucket 4 for dissolution testing; a groove is opened on the upper surface of the base 3, and the soil sample bucket 4 is placed in the groove. This can limit the soil sample bucket 4 on the upper surface of the base 3 and prevent the soil sample bucket 4 from moving during the pressure application process. A water outlet 12 is provided on the base 3 to discharge the water injected during the test into the soil sample container 4; it also includes a collection tank 10, which is connected to the water outlet 12 via a drainage pipe 9 to collect the water discharged from the solution test; a drainage control valve 16 is installed on the drainage pipe 9 to control the opening and closing of the water outlet 12 and the collection tank 10 as needed. Collecting water facilitates subsequent testing and effectively saves water resources. The resistivity testing system 11 includes a resistivity testing device and multiple electrodes 13, wherein the resistivity testing device is a network parallel resistivity transilluminator; as... Figure 2 As shown, multiple mounting holes are opened on the side wall of the soil sample bucket 4, and multiple electrodes 13 are installed in each mounting hole respectively and in contact with the coarse-grained saline soil inside the soil sample bucket 4. Each electrode 13 is connected to the resistivity testing device. The potential data of each electrode 13 during the solution collapse test is obtained in real time through the resistivity testing device, which is used for subsequent imaging of the interior of the coarse-grained saline soil.

[0021] As an improvement of the present invention, the connecting mechanism is a bolt. Using bolts facilitates the installation, fixing, and disassembly of the upper cover 5, soil sample container 4, and base 3, and makes it convenient to replace the internal coarse-grained saline soil. The displacement measuring device is a dial gauge 7, which is fixed to the upper surface of the upper cover 5. The probe of the dial gauge 7 contacts the support beam on the upper part of the reaction frame 1. When the dial gauge 7 moves upward with the upper cover 5, the probe of the dial gauge 7 continuously measures the change in distance between itself and the support beam, thereby determining the stress and deformation of the coarse-grained saline soil inside the soil sample container 4.

[0022] As another improvement of the present invention, such as Figure 2 As shown, the soil sample container 4 has two rows of mounting holes on its side wall. Each row of mounting holes is arranged along the axial direction of the soil sample container 4, and the two rows are symmetrically arranged about the axis of the soil sample container 4. This arrangement of the mounting electrodes 13 improves the resistivity acquisition range for coarse-grained saline soil, facilitating subsequent imaging. The electrodes 13 are sealed to the mounting holes with epoxy resin 14. This ensures the airtightness between the electrodes 13 and the mounting holes, preventing coarse-grained saline soil from overflowing from the mounting holes during the test.

[0023] As another improvement of the present invention, both the soil sample bucket 4 and the pressure head mechanism 6 are made of polyetheretherketone (PEEK). This material has sufficient rigidity to ensure accurate deformation measurement, and also has an insulating effect to reduce the influence of external boundaries on the test results.

[0024] The working process of this utility model is as follows: the soil sample bucket 4 is inserted into the groove of the base 3, coarse-grained saline soil is put into the soil sample bucket 4, the pressure head mechanism 6 and the upper cover 5 are installed in the corresponding positions in sequence, the upper cover 5 is tightened with bolts, and the dial gauge 7 is installed and fixed. The resistivity testing device is connected to each electrode 13 on the soil sample bucket 4 by wires; the axial pressure mechanism 2 provides a constant consolidation pressure, which is applied in stages at 50, 100, 200, 400 and 800 kPa respectively. First, the axial compression mechanism is activated with a pressure of 50 kPa. This drives the base 3, soil sample container 4, and top cover 5 upwards, while the pressure head mechanism 6 remains stationary. Consolidation stress is applied to the coarse-grained saline soil through the pressure head mechanism 6, soil sample container 4, and base 3. If the difference in readings of the dial gauge 7 is no greater than 0.05 mm after 1 hour under this fixed pressure, it indicates that the current consolidation stress has stabilized the deformation of the coarse-grained saline soil. The current applied pressure value is maintained. Then, the drainage control valve 16 is opened, and the pressure water source 8 is injected into the soil sample container 4 through the permeable hole 15 at the set pressure. A solution collapse test is then performed on the coarse-grained saline soil under the current consolidation pressure. Simultaneously, the power is turned on. The resistivity testing device collects the potential value of the electrode 13 around the coarse-grained saline soil every 10 minutes and records the reading of dial gauge 7 every half hour. Since the solution process causes changes in the interior of the coarse-grained saline soil, its overall shape is further compressed. The solution test is stopped when the difference between two dial gauge 7 readings 1 hour apart is less than or equal to 0.05 mm. Then, the solution deformation of the soil sample is calculated based on the reading of dial gauge 7 to complete the solution deformation test. Finally, based on the collected potential data, the resistivity distribution image of the coarse-grained saline soil during the solution test under the consolidation pressure is obtained by inversion using the software built into the resistivity testing device.

[0025] The above process was repeated at subsequent pressures of 100, 200, 400, and 800 kPa to obtain resistivity distribution images during the solution collapse test of coarse-grained saline soil under different consolidation pressures.

[0026] The above description is only a preferred embodiment of the present utility model. 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 utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A device for testing the dissolution of coarse-grained saline soil with resistivity imaging, characterized in that, It includes a reaction frame, axial compression mechanism, base, soil sample bucket, top cover, pressure head mechanism, displacement measuring device, pressure water source, and resistivity testing system; The axial compression mechanism is installed in the middle of the reaction frame, and the base is fixed on the upper part of the pressure end of the axial compression mechanism. The soil sample bucket is a cylindrical shape with open ends placed on the base, used to hold coarse-grained saline soil. The upper cover is placed on the upper part of the soil sample bucket, and the upper cover is connected to the base through a connecting mechanism, so that the upper cover, soil sample bucket and base are pressed and fixed together. The pressure head mechanism is located inside the soil sample container and includes a pressure plate and a pressure rod. One end of the pressure rod is fixedly connected to the center of the pressure plate, and the axis of the pressure rod is perpendicular to the upper surface of the pressure plate. A through hole is opened in the center of the upper cover, and the other end of the pressure rod extends out of the soil sample container from the through hole and is fixedly connected to the support beam on the upper part of the reaction frame. When the axial pressure mechanism drives the base and the soil sample container to move upward, the pressure head mechanism remains stationary, thereby applying stress to the coarse-grained saline soil. A displacement measuring device is installed on the upper cover to measure the stress deformation of the coarse-grained saline soil during the stress application process. The pressure rod has a water-permeable hole at the top and a water inlet hole at the bottom of the pressure plate. The water-permeable hole and the water inlet hole are connected through the water flow channel inside the pressure rod and the pressure plate. The pressure water source is connected to the water-permeable hole and is used to inject water into the soil sample bucket for dissolution testing. The base has a water outlet hole and is used to discharge the water injected for testing from the soil sample bucket. The resistivity testing system includes a resistivity testing device and multiple electrodes. Multiple mounting holes are opened on the side wall of the soil sample bucket, and multiple electrodes are installed in each mounting hole and in contact with the coarse-grained saline soil inside the soil sample bucket. Each electrode is connected to the resistivity testing device. The potential data of each electrode during the solution collapse test is acquired in real time through the resistivity testing device, which is used for subsequent imaging of the interior of the coarse-grained saline soil.

2. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, A groove is formed on the upper surface of the base, and the soil sample bucket is placed in the groove.

3. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, It also includes a collection tank, which is connected to the outlet via a drainage pipe to collect the water discharged from the solution trap test; the drainage pipe is equipped with a drainage control valve to control the connection and disconnection between the outlet and the collection tank as needed.

4. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, The connecting mechanism is a bolt.

5. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, The displacement measuring device is a dial gauge, which is fixed on the upper surface of the cover. The probe of the dial gauge is in contact with the support beam at the top of the reaction frame. When the dial gauge moves upward with the cover, the probe of the dial gauge continuously measures the change in distance between it and the support beam, thereby determining the stress and deformation of the coarse-grained saline soil in the soil sample bucket.

6. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, The soil sample container has two rows of mounting holes on its side wall. Each row of mounting holes is arranged along the axial direction of the soil sample container, and the two rows are symmetrical about the axis of the soil sample container.

7. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, The electrode is sealed to the mounting hole with epoxy resin.

8. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, Both the soil sample bucket and the pressure head mechanism are made of polyetheretherketone (PEEK).

9. The coarse-grained saline soil solution collapse testing device with resistivity imaging according to claim 1, characterized in that, The resistivity testing device is a network parallel resistivity meter.

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