A micro-vibration table test method for potential study of silty sand body

Abstract

The application discloses a micro-vibration table test method for studying the potential of silty sand, and the specific steps are as follows: (1) making the long side of the soil box parallel to the excitation direction; (2) drawing grid mark lines on one side of the long side of the transparent glass jar; (3) fixing the glass jar on the reciprocating oscillator; (4) testing the maximum and minimum dry densities of any silty sand; (5) dyeing the silt particles red and the sand particles natural color, and stirring uniformly for standby; (6) preparing a sample with an initial relative density of 20% in the transparent glass jar; (7) starting the vibration test; (8) processing the high-definition image recorded by the camera; and (9) comparing the test results, studying the contact state of the sand and silt mixture particles, the vibration influence, and the influence mechanism of the silt content on the potential of the sandy soil body. The application has the following advantages: (1) the test can record the development law of the ground settlement with the vibration times, and can analyze the influence of the silt content on the potential of the sandy soil body; and (2) the test can record the contact state and mutual displacement trend of the sand and silt particles in the vibration process through the high-pixel camera.

Description

Technical Field

[0001] This invention relates to the field of simulated earthquake technology, specifically to a miniature shaking table test method for studying the potential variation of fine sand bodies. Background Technology

[0002] Over the past 30 years, widespread liquefaction and the resulting severe damage to surface structures and underground infrastructure have repeatedly occurred in catastrophic earthquakes around the world. Fine-grained sandy soils are widely distributed in nature, and their liquefaction or subsidence hazards in earthquakes have become increasingly prominent. However, there are still many uncertainties regarding the earthquake damage mechanisms and prediction methods for fine-grained sandy soils.

[0003] Research on the influence of fine particle content on the liquefaction potential of sandy soil has been fraught with contradictions and controversies, and a large number of indoor test results have not been of substantial significance for improving the field liquefaction discrimination method for silty sand and silt.

[0004] Earthquake simulation shaking tables can effectively reproduce earthquake processes and conduct artificial seismic wave tests. They are the most direct method for studying the seismic response and failure mechanisms of soil foundations and buildings / structures in the laboratory. However, even small shaking tables used in geotechnical testing have drawbacks such as high testing costs and time-consuming and labor-intensive sample preparation due to large sample sizes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a micro-vibration table test method for studying the potential variation of fine sand bodies.

[0006] To achieve the purpose of adjustable usage angle mentioned in the background section, the present invention provides the following technical solution:

[0007] A micro-vibration table test method for studying the potential variation of fine sand bodies, the specific steps of which are as follows:

[0008] (1) The micro vibration table uses a transparent glass cylinder as a soil box with dimensions of 35cm*20cm*22cm. The soil height during the test is 15cm. In order to obtain the maximum "planar size ratio" and reduce the influence of sand box boundary reflection, the long side (35cm) of the soil box is parallel to the excitation direction.

[0009] (2) On one side of the long side (35cm), mark a grid of lines for filling soil, with a length of 35cm and a height of 15cm. The spacing between the lines is 1cm. Figure 3 As shown. This serves as a relative coordinate system, used to analyze the relative displacement of soil particles during vibration.

[0010] (3) Fix the glass cylinder on the SLY-DZ01 reciprocating oscillator with a vibration frequency of 0-100 rpm, a maximum allowable displacement of ±20 mm on the table, and a maximum load of 30 kg.

[0011] (4) For any sandy soil containing silt, test the maximum and minimum density according to the relative density test method in the Geotechnical Test Code;

[0012] (5) Pass the mixture through a 0.075mm sieve to separate the sand particles and silt particles from the above-mentioned sand. Dye the silt particles red and leave the sand particles in their natural color. Mix them thoroughly according to a certain mass content of silt particles and set aside.

[0013] (6) Prepare samples in a transparent glass tank at an initial relative density of 20%;

[0014] (7) The vibration test was started using the SLY-DZ01 reciprocating oscillator, and the test process of the long side (35cm) of the transparent glass tank was recorded using a high-pixel camera mounted on a tripod.

[0015] (8) Process the high-resolution image of the long side (35cm) of the glass tank recorded by the camera, measure it proportionally (grid marking lines, with a spacing of 1cm in both directions), and analyze the displacement process of the dyed powder particles and the changing characteristics of the relative position of the powder particles among the sand particles during the processing experiment. Investigate whether the powder particles changed from participating in the soil particle skeleton to filling the pores between coarse particles, or the opposite change, and the development process of surface settlement with the number of vibrations;

[0016] (9) Compare the test results of the above (8) test results of samples with different powder contents, study the particle contact state and vibration influence of sand-powder mixture, and the influence mechanism of powder content on the change potential of sandy soil.

[0017] The advantages of this patent are:

[0018] (1) From a macroscopic perspective, this experiment can record the development law of surface settlement with the number of vibrations, and the void ratio can be converted from the settlement, and the relative density can be converted from the void ratio. Therefore, the number of vibrations required for four specified relative density ranges, such as 20%-35%-50%-65%-80%, can be obtained by analyzing the experimental data. By comparing the number of vibrations required for the four ranges of sandy soil with different silt contents, the influence of silt content on the change potential of sandy soil can be analyzed.

[0019] (2) From a microscopic perspective, this experiment used a high-resolution camera to record the contact state and mutual displacement trend of sand and powder particles during vibration. The powder particles were stained to facilitate observation. The resulting analysis will significantly improve our understanding of the particle contact model of sand and powder mixtures and the settling mechanism after vibration.

[0020] Based on the above two findings, and through this experimental method, a large number of tests were conducted on various types of sand and non-plastic silt widely distributed in nature. It is expected that a more objective and comprehensive understanding will be formed on the influence of silt content on liquefaction potential and the liquefaction discrimination of fine sand. Attached Figure Description

[0021] Figure 1 A schematic diagram of a miniature vibration table.

[0022] Figure 2 Illustration of a transparent fiberglass product

[0023] Figure 3 Schematic diagram of transparent fiberglass grid marking lines

[0024] Figure 4 Schematic diagram of the particle state of a mixture of sand and powder

[0025] Figure 5 Schematic diagram of the contact state of coarse and fine mixed particles Detailed Implementation

[0026] A micro-vibration table test method for studying the potential variation of fine sand bodies, the specific steps of which are as follows:

[0027] (1) As Figure 1-2 As shown. The micro vibration table uses a transparent glass cylinder as the soil box, with dimensions of 35cm*20cm*22cm. The soil height during the test was 15cm. In order to obtain the maximum "planar size ratio" and reduce the influence of sand box boundary reflection, the long side (35cm) of the soil box was made parallel to the excitation direction.

[0028] (2) On one side of the long side (35cm), mark a grid of lines for filling soil, with a length of 35cm and a height of 15cm. The spacing between the lines is 1cm. Figure 3 As shown. This serves as a relative coordinate system, used to analyze the relative displacement of soil particles during vibration.

[0029] (3) Fix the glass cylinder on the SLY-DZ01 reciprocating oscillator with a vibration frequency of 0-100 rpm, a maximum allowable displacement of ±20 mm on the table, and a maximum load of 30 kg.

[0030] (4) For any sandy soil containing silt, test the maximum and minimum dry density according to the relative density test method in the Geotechnical Test Code;

[0031] (5) Pass the mixture through a 0.075mm sieve to separate the sand particles and silt particles from the above-mentioned sand. Dye the silt particles red and leave the sand particles in their natural color. Mix them thoroughly according to a certain mass content of silt particles and set aside.

[0032] (6) Prepare samples in a transparent glass tank at an initial relative density of 20%;

[0033] (7) The vibration test was started using the SLY-DZ01 reciprocating oscillator, and the test process of the long side (35cm) of the transparent glass tank was recorded using a high-pixel camera mounted on a tripod.

[0034] (8) Process the high-resolution image of the long side (35cm) of the glass tank recorded by the camera, measure it proportionally (grid marking lines, with 1cm spacing in both directions), and analyze the displacement process of the stained powder particles and the changes in the relative positions of the powder particles among the sand particles during the processing experiment. Investigate whether the powder particles participate in the formation of the soil particle skeleton (such as...). Figure 5 State 2) becomes filled with pores between coarse particles (such as...) Figure 5 State 1), or the opposite change, and the development process of surface subsidence with the number of vibrations;

[0035] (9) such as Figure 4 As shown, by comparing the test results of the above-mentioned item (8) of the samples with different powder contents, the particle contact state and vibration influence of the sand-powder mixture were studied, as well as the influence mechanism of powder content on the change potential of sandy soil.

[0036] The advantages of this patent are:

[0037] (1) From a macroscopic perspective, this experiment can record the development law of surface settlement with the number of vibrations, and the void ratio can be converted from the settlement, and the relative density can be converted from the void ratio. Therefore, the number of vibrations required for four specified relative density ranges, such as 20%-35%-50%-65%-80%, can be obtained by analyzing the experimental data. By comparing the number of vibrations required for the four ranges of sandy soil with different silt contents, the influence of silt content on the change potential of sandy soil can be analyzed.

[0038] (2) From a microscopic perspective, this experiment used a high-resolution camera to record the contact state and mutual displacement trend of sand and powder particles during vibration. The powder particles were stained to facilitate observation. The resulting analysis will significantly improve our understanding of the particle contact model of sand and powder mixtures and the settling mechanism after vibration.

[0039] Based on the above two findings, and through this experimental method, a large number of tests were conducted on various types of sand and non-plastic silt widely distributed in nature. It is expected that a more objective and comprehensive understanding will be formed on the influence of silt content on liquefaction potential and the liquefaction discrimination of fine sand.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A micro-vibration table test method for studying the potential variation of fine sand bodies, characterized in that, The specific steps are as follows: (1) The micro vibration table uses a transparent glass cylinder as a sand box with dimensions of 35cm*20cm*22cm. The soil height during the test is 15cm. In order to obtain the maximum plane size ratio and reduce the influence of sand box boundary reflection, the long side of the sand box is parallel to the excitation direction. (2) On the long side of the transparent glass tank, draw grid marking lines with a soil filling range of 35cm in length and 15cm in height, with a vertical and horizontal spacing of 1cm, as a relative coordinate system for analyzing the relative displacement of soil particles during vibration. (3) Fix the glass cylinder on the SLY-DZ01 reciprocating oscillator with a vibration frequency of 0-100 rpm, a maximum allowable displacement of ±20 mm on the table, and a maximum load of 30 kg. (4) For any sandy soil containing silt, test the maximum and minimum dry density according to the relative density test method in the Geotechnical Test Code; (5) Pass through a 0.075mm sieve to separate sand particles and silt particles in the sand. Dye the silt particles red and leave the sand particles in their natural color. Mix thoroughly according to a certain mass content of silt particles and set aside. (6) Prepare samples in a transparent glass tank at an initial relative density of 20%; (7) The vibration test was started using the SLY-DZ01 reciprocating oscillator, and the test process of the long side of the transparent glass tank was recorded using a high-pixel camera mounted on a tripod. (8) Process the high-definition image of the long side of the glass tank recorded by the camera, measure it proportionally, and the grid marking line spacing is 1cm. Analyze the displacement process of the dyed powder particles in the processing test, the change characteristics of the relative position of the powder particles between the sand particles, and examine whether the powder particles changed from participating in the soil particle skeleton to filling the pores between coarse particles, or the opposite change, as well as the development process of surface settlement with the number of vibrations. (9) Compare the test results of the above (8) test results of samples with different powder contents, study the particle contact state and vibration influence of sand-powder mixture, and the influence mechanism of powder content on the change potential of sandy soil.

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