CN216309983U - An integrated test device for consolidation expansion and shrinkage of fine-grained soil and dry-wet cycle - Google Patents

Abstract

A fine grained soil consolidation swelling and shrinkage and dry-wet cycle integrated test device comprises an outer ring container used for simulating temperature, humidity and wind speed conditions; the annular inner ring container is used for applying lateral pressure to the multi-cavity film covering structure, and a lower permeable plate is arranged in an open area formed in the inner ring container; a sample is arranged above the lower porous plate, an upper porous plate, a pressurizing base and a top cover are sequentially arranged on the top surface of the sample from bottom to top, a plurality of displacement sensors in a no-load state are arranged on the lower end surface of the top cover, the upper end surface of the pressurizing base is connected with an external pressurizing mechanism, a pressure sensor and a displacement sensor in a load state are arranged on the pressurizing base, a temperature, humidity and wind speed sensor is arranged on the inner wall of the outer ring container, and a water content sensor is arranged around the sample; the various sensors, the displacement meter and the camera are connected with a multi-channel data acquisition instrument; the utility model also discloses a corresponding test method; the change of the consolidation expansion and shrinkage of the soil body of the fine-grained soil under different dry and wet cycle conditions is evaluated more comprehensively; the test efficiency, the flexibility, the applicability and the accuracy are improved.

Description

An integrated test device for consolidation expansion and shrinkage of fine-grained soil and dry-wet cycle

technical field

The utility model relates to the fields of geotechnical mechanics and engineering, in particular to an integrated test device for fine-grained soil consolidation, expansion and contraction and dry-wet cycle and a test method thereof, which is suitable for but not limited to studying the consolidation, expansion and contraction of various types of soils and a test method thereof. Wet and dry cycle characteristics.

Background technique

The capacity of fine-grained soil to increase in volume due to the increase in moisture content is called expansion; the capacity to shrink in volume due to loss of water in the soil is called shrinkage. The increase and decrease of moisture content in fine-grained soil are mainly caused by external factors, such as precipitation, changes in surface water and groundwater, and changes in temperature and humidity. The expansion and contraction of fine-grained soil has a great influence on engineering buildings. The expansion and contraction of soil not only reduces the strength of soil, but also causes soil deformation and damage to buildings. Slopes composed of fine-grained soil often cause landslides due to soil expansion, which brings harm to the project. Therefore, it is of great significance to study the expansion and shrinkage of fine-grained soil in engineering practice. In engineering construction, structures built on expansive soil with constant water content will not suffer damage caused by expansion and contraction. When the water content of soil changes, volume expansion in both vertical and horizontal directions occurs immediately. A slight change in moisture content, in amounts of only 1% to 2%, is sufficient to cause detrimental swelling. An in-depth understanding of the expansion and contraction characteristics of fine-grained soil is the key to solving the engineering problems caused by the expansion and contraction of fine-grained soil. The expansion and shrinkage of fine-grained soil is greatly affected by its degree of consolidation and the variation of dry-wetting cycles. The key to understanding the expansion and contraction of fine-grained soil is to study the consolidation and expansion and contraction of fine-grained soil under different dry-wetting cycles.

The current related test devices all have the following shortcomings:

(1) The fine-grained soil consolidation expansion-shrinkage and dry-wet cycle integrated test device of the present utility model, the consolidation test, expansion test, shrinkage test and dry-wet cycle test of the former fine-grained soil are all performed separately in different test equipment. Completed, the test is not continuous, and repeated sampling and loading is required, and the soil is disturbed many times, and the error of the test results is large;

(2) At present, the expansion test of fine-grained soil only measures the change in the vertical direction of the sample during the expansion process, and does not measure the change in the horizontal direction;

(3) At present, most of the shrinkage tests of fine-grained soil only measure the vertical shrinkage of the soil body, and cannot measure the real-time volume change during the soil body shrinkage process;

(4) At present, most of the expansion and contraction test devices of fine-grained soil cannot adjust the lateral pressure and cannot simulate different stress states of soil under different engineering conditions. Therefore, it is necessary to design a high-efficiency fine-grained soil consolidation expansion and shrinkage and dry-wet cycle integrated test device to systematically complete the consolidation expansion and dry-wet cycle test of fine-grained soil, and measure the soil under different dry-wet cycle conditions. Consolidation and expansion and shrinkage properties of the soil, thus providing further support for the research on the expansion and contraction properties of fine-grained soils.

Utility model content

In order to solve the deficiencies or shortcomings of the prior art, the utility model provides an efficient integrated test device for fine-grained soil consolidation, expansion, shrinkage and dry-wet cycle. It completes the consolidation test, expansion test, shrinkage test and dry-wet cycle test in the same device, which comprehensively reflects the changes of soil consolidation and expansion-shrinkage under different dry-wet cycle conditions, avoids repeated tests, and saves tests. Time, reduce the disturbance to the soil during the test, and can control the lateral pressure of the soil, and measure the volume change of the soil in the vertical and horizontal directions in real time.

In order to achieve the above purpose, the utility model relates to: an integrated test device for fine-grained soil consolidation, expansion, shrinkage and dry-wet cycle, comprising an outer-circle container for simulating temperature, humidity, and wind speed conditions; the outer-circle container is a cavity structure and is provided with The air inlet pipe with the No. 1 valve and the air outlet pipe with the No. 2 valve are connected with the temperature, humidity and wind speed controller, and the inner bottom surface of the outer ring container is provided with an annular inner ring container for applying lateral pressure. , the open area formed inside the inner ring container is provided with a lower permeable plate; a sample is arranged above the lower permeable plate, and the top surface of the sample is sequentially provided with an upper permeable plate, a gland plate, a pressurized base and a top. Cover, the lower end face of the top cover is provided with a plurality of unloaded state displacement sensors (including No. 1 displacement sensor, No. 2 displacement sensor, No. 3 displacement sensor, No. 4 displacement sensor), the upper end face of the pressure base and the external pressure mechanism A pressure sensor and a loaded state displacement sensor are arranged on the pressurized base, a temperature, humidity, and wind speed sensor is arranged on the inner wall of the outer ring container, and a water content sensor is arranged around the sample. The sensor, displacement meter, camera and multi-channel data The acquisition instrument is connected, and the multi-channel data acquisition instrument signal is connected to the computer processing system through the data line;

The inner ring container includes a rigid multi-chamber structure, and the multi-chamber structure includes an upper chamber, a middle chamber and a lower chamber arranged in sequence from top to bottom, and the ends of the upper chamber, the middle chamber and the lower chamber close to the sample are all open structures They are covered with independent and sealed rubber films (including the upper cavity rubber film, the middle cavity rubber film, and the lower cavity rubber film)), and an outer layer of rubber that is in direct contact with the sample is also arranged between the multi-cavity structure and the sample. Membrane; the middle cavity is connected to the No. 1 pressurized pipe, the upper and lower chambers are connected to the No. 2 pressurized pipe, and the interior of the multi-cavity structure can be filled with water to apply lateral pressure to the sample; the outer rubber film is in direct contact with the sample , the rubber film expands and contracts with the sample;

Further, the temperature, humidity and wind speed controller includes a heater for adjusting air temperature, a humidifier for adjusting air humidity, and a fan for adjusting air flow rate.

Further, the upper cavity and the lower cavity are protective cavities, the middle cavity is a measurement cavity, and the height of the middle cavity is not greater than the height of the shrinkage limit of the sample.

Further, the upper permeable plate and the lower permeable plate are made of alumina or non-corroded metal materials, the permeability coefficient of which should not be greater than that of the sample, and the diameter of the upper permeable plate should be smaller than the diameter of the sample by 0.2-0.5mm. .

Further, the water content sensor includes three probes, and the three probes are equally spaced around the sample and located between the sample and the rubber film. Under the action of the confining pressure exerted by the inner ring container, one side is close to the sample. Contact, measure the volumetric moisture content of the sample, the measurement range is 0-100%.

In general, compared with the prior art, the following beneficial effects can be achieved through the above technical solutions conceived by the present utility model:

(1) The consolidation test, expansion test, shrinkage test and dry-wet cycle test of fine-grained soil can be completed in the same test equipment, and the continuity between tests is better; The soil is basically not disturbed during the process, and the test results are more accurate;

(2) It can more comprehensively evaluate the change of soil consolidation expansion and contraction properties of fine-grained soil under different dry-wetting cycle conditions, and has a wide range of application prospects;

(3) Different dry and wet cycle conditions, consolidation pressure and lateral pressure can be set according to the test needs, the operation is simple and easy, and the test efficiency, flexibility, applicability and accuracy are improved.

Description of drawings

Fig. 1 is the structural representation of the preferred embodiment of the present utility model;

FIG. 2 is a schematic diagram of the partial structure of the multi-chamber structure of the preferred embodiment of the present invention (sample 5 only shows part);

Fig. 3 is the partial structure schematic diagram of the rubber film place of the preferred embodiment of the present utility model;

Fig. 4 is the partial top view of the sample place of the preferred embodiment of the present utility model;

In the figure: 1-top cover; 2-pressurized base; 3-pressurized cover plate; 4-upper permeable plate; 5-sample; 6-lower permeable plate; 7-outer ring container; 8-inner ring container ; 9- No. 1 pressurized pipeline; 10- Air pump; 11- No. 1 valve, 11b- No. 2 valve, 11c- No. 3 valve, 11d- No. 4 valve; 12- Heating machine; 13- Humidifier; 14- Fan; 15- temperature, humidity and wind speed controller; 16- multi-channel data acquisition instrument; 17- computer processing system; 18- pressure sensor; 19- load state displacement sensor; 20- unload state displacement sensor; 20a- a No. displacement sensor, 20b-No.2 displacement sensor, 20c-No.3 displacement sensor, 20d-No.4 displacement sensor; 21-Temperature, humidity and wind speed sensor; 22a-No.1 moisture content sensor probe, 22b-No.2 moisture content sensor probe, 22c-No.3 moisture content sensor probe; 23a-No.1 flow sensor; 23b-No.2 flow sensor; 24-Camera; 25-Multi-cavity structure; Cavity rubber membrane; 26d-outer rubber membrane; 27-upper cavity; 28-middle cavity; 29-lower cavity; 30-No. 2 pressure pipeline.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as there is no conflict with each other.

Example 1:

As shown in Figures 1 to 2, an integrated test device for fine-grained soil consolidation, expansion, shrinkage and dry-wet cycle includes an outer container 7 for simulating temperature, humidity and wind speed conditions; the outer container 7 is a cavity structure and is provided with The air inlet pipe 71 with the No. 1 valve 11a and the air outlet pipe 72 with the No. 2 valve 11b are connected with the temperature, humidity and wind speed controller 15. The annular inner ring container 8 of the pressure, the open area formed inside the inner ring container 8 is provided with a lower water permeable plate 6; the sample 5 is arranged above the lower water permeable plate 6, and the top surface of the sample 5 is sequentially arranged from bottom to top. The water permeable plate 4, the pressurizing base 2 and the top cover 1, the lower end surface of the top cover 1 is provided with a plurality of unloaded state displacement sensors 20, the upper end surface of the pressurizing base 2 is connected with an external pressurizing mechanism, and the pressurizing base 2 A pressure sensor 18 and a loaded state displacement sensor 19 are arranged on it, a temperature, humidity, and wind speed sensor 21 is arranged on the inner wall of the outer ring container 7, and a moisture content sensor 22 is arranged around the sample 5. The multi-channel data acquisition instrument 16 is connected, and the signal of the multi-channel data acquisition instrument 16 is connected to the computer processing system 17 through the data line.

Preferably, the upper permeable plate 4 and the lower permeable plate 6 are made of alumina or non-corroded metal materials, the permeability coefficient of which should not be greater than that of the sample, and the diameter of the upper permeable plate should be smaller than the diameter of the sample by 0.2-0.5 mm;

Preferably, the loaded state displacement sensor 19, No. 1 displacement sensor 20a, No. 2 displacement sensor 20b, No. 3 displacement sensor 20c, No. 4 displacement sensor 20d have an accuracy of 0.2% of the full scale.

2 and 3, the inner ring container 8 includes a rigid multi-chamber structure 25, and the multi-chamber structure includes an upper chamber 27, a middle chamber 28 and a lower chamber 29 arranged in sequence from top to bottom. The upper chamber 27, the middle chamber The ends of the cavity 28 and the lower cavity 29 close to the sample 5 are both open structures and each is covered with a rubber film that is independent and sealed. The rubber film 26d (the outer rubber film 26d expands and contracts with the sample 5); the middle cavity 28 is connected with the No. 1 pressure pipeline 9 (built-in or external pressure pump), and the upper cavity 27 and the lower cavity 29 are connected with the No. 2 pressure pipeline 30 connections, the multi-chamber structure can be filled with water to apply lateral pressure to the sample. Each cavity is connected with No. 1 pressurizing pipe 9 (built-in or external pressurizing pump), and the interior can be filled with water to apply lateral pressure to the sample. The upper chamber 27 and the lower chamber 29 are protective chambers, the middle chamber 28 is a measuring chamber, and the height of the middle chamber is not greater than the height of the shrinkage limit of the sample.

Preferably, the temperature, humidity and wind speed controller 15 includes a heater 12 for adjusting the air temperature, a humidifier 13 for adjusting the air humidity, and a fan 14 for adjusting the air flow rate.

Please refer to FIG. 4, the water content sensor 22 includes three probes No. 1 water content sensor probe 22a, No. 2 water content sensor probe 22b, and No. 3 water content sensor probe 22c, which are equally spaced around the sample 5, located in the sample Between 5 and the rubber film 26, under the action of the confining pressure exerted by the inner ring container 8, one side is in close contact with the sample 5, and the volumetric moisture content of the sample is measured, and the measurement range is 0-100% (such as Tiannuo TDR -6A soil temperature and humidity sensor).

Preferably, the multi-channel data acquisition instrument 16, with multiple parallel sampling channels, can simultaneously correspond to multiple pressure sensors 18, a loaded state displacement sensor 19, an unloaded state displacement sensor 20, a moisture content sensor 22, and a temperature, humidity, and wind speed sensor 21. , No. 1 flow sensor 23a, No. 2 flow sensor 23b and camera 24 for data collection and communication transmission (commercially available multi-channel data collector, no less than 32 channels, such as AT4516 multi-channel data collector).

Place the sample 5 in the circular position inside the inner ring container 8 of the device, and place the permeable stone and filter paper on the top and bottom of the sample. A pressurized cover plate 3 and a pressurized base 2 are placed on the upper permeable plate 4 in sequence, and a top cover 1 is covered, and the top cover 1 is connected to an external pressurizing device. One side of the pipe of the outer ring container 7 is connected to the temperature, humidity and wind speed controller 15 as an air inlet, and the other side of the pipe is connected to the air pump 10 as an air outlet. The pipelines on both sides of the inner ring container 8 are connected to the No. 1 pressurized pipeline 9 . The camera 24 is mounted on the top cover 1 . The moisture content sensor 22 is placed on the rubber film 26 and the sample 5 , and is in close contact with the sample 5 .

Example 2:

The sample to be tested is yellowish-brown, in a hard plastic state, and contains black iron-manganese nodules. It is a ring knife sample with a diameter of 61.8mm and a height of 20mm cut from undisturbed soil. The moisture content is 17.0% and the dry density is 1.77g/ ^cm3 . .

Step 1: Place the device on the operating platform, and connect each sensor to the multi-channel data acquisition instrument 16 . The multi-channel data acquisition instrument 16 is connected to the computer processing system 17 .

Step 2: Place the lower permeable plate 6 in the container, place the sample 5 on the lower permeable plate 6, place thin filter paper between the sample 5 and the lower permeable plate 6, and place the thin filter paper on the sample 5 in turn, and the upper permeable plate. board 4;

Step 3: Open the No. 3 valve 11c and No. 4 valve 11d, fill the inner ring container with water, and keep the volume of water in the inner ring container unchanged according to the test conditions.

Step 4: Place the pressurized cover plate 3 and the pressurized base 2 on the upper permeable plate 4 so that the center of the pressurized cover plate 3 and the pressurized base 2 are aligned.

Step 5: Connect the device to the pressurizing device, determine the consolidation pressure at all levels to be applied, and start consolidation. The height change of the sample is recorded by the loaded state displacement sensor 19, and the applied pressure is recorded by the pressure sensor 18. After each level of pressure is applied, when the deformation reaches 0.01mm per hour, the height change of the sample is measured as the stability standard. Follow this step Pressurize step by step until the end of the test.

Carry out the above steps to complete the consolidation test.

Example 3:

Step 1: Same as step 1 in Example 2.

Step 2: Same as Step 2 of Example 2.

Step 3: Same as Step 3 of Example 2.

Step 4: Cover the top cover 1 , so that the No. 1 displacement sensor 20 a , the No. 2 displacement sensor 20 b , and the No. 3 displacement sensor 20 c are in contact with the upper permeable plate 4 .

Step 5: Open the No. 1 valve 11a, close the No. 2 valve 11b, pour pure water into the container from bottom to top, and keep the water surface 5mm above the sample, the difference between the displacement meter readings within 2 hours does not exceed 0.01mm, and the expansion is stable .

Carry out the above steps to complete the unloaded expansion test.

Example 4:

Step 1: Same as step 1 in Example 2.

Step 2: Same as step 2 in Example 2.

Step 3: Open the valves 11c and 11d, fill the inner ring container with water, set a certain water pressure according to the test conditions, and apply lateral pressure to the sample. The water pressure of the upper and lower protection chambers is slightly greater than that of the middle chamber. .

Step 4: Same as step 4 in Example 3.

Step 5: Open the No. 1 valve 11a and the No. 2 valve 11b. According to the test conditions, set the temperature, humidity and wind speed of the air. One side of the pipe connected to the temperature, humidity and wind speed controller 15 is the air inlet, and the other side of the pipe connected to the air pump 10 is the air outlet to keep the air inside the device circulating.

During the test, the temperature, humidity and wind speed sensor 21 records the temperature, humidity and wind speed of the air actually passing through the device, the moisture content sensor 22 records the moisture content change of the sample, the unloaded state displacement sensor 20 records the vertical height change of the sample, and the camera 24 records. The development of cracks on the surface of the sample, the No. 1 flow sensor 23a arranged in the No. 1 pressurizing pipe 9 and the No. 2 flow sensor 23b arranged in the No. 2 pressurizing pipe 30 record the radial volume change of the sample, and calculate The radius value at any time of the sample.

The calculation formula involved in the test:

During the test, the radius value r _t of the sample at any time:

r _t ——the radius of the sample at time t, cm;

r ₀ ——the initial radius of the sample, cm;

ΔV——The volume change of the measuring cavity in the middle cavity during t time, cm ³ ;

h _m ——The height of the measuring cavity of the middle cavity, cm.

Example 5:

After carrying out Example 2, remove the pressurized base 2 and the pressurized cover plate 3, carry out step 4 and step 5 in Example 3, then open No. 1 valve 11a and No. 2 valve 11b, discharge the moisture in the device, and then Step 5 in Example 4 was carried out.

Carry out the above steps to complete the consolidation expansion and contraction integration test of the sample.

Example 6:

While carrying out Example 4, the temperature, humidity and wind speed of the air at the air inlet can be changed, and the dry-wet cycle test of the sample under different conditions and times can be carried out.

During the expansion test, the changes in the vertical and horizontal directions of the soil body during the expansion process can be measured in real time; during the shrinkage test process, the changes in the vertical direction and girth of the soil body during the shrinkage process can be measured in real time, and the volume change of the soil body during the shrinkage process can be obtained. ; During the expansion and contraction test of fine-grained soil, the lateral pressure can be adjusted to simulate the in-situ stress level at different depths.

Using the above-mentioned high-efficiency fine-grained soil consolidation expansion and shrinkage and dry-wet cycle integrated test device, it can more comprehensively reflect the soil structure changes during the dry-wet cycle process, avoid repeated tests, and reduce test time. The device is simple in design and structure, easy to operate, and has good stability. Each group of components is durable, not easy to wear, and has strong practicability and high precision. One or more different test paths can be set according to the needs of the test. Efficiency, flexibility, applicability and accuracy can more comprehensively evaluate changes in soil moisture content, expansion and contraction, consolidation characteristics and surface crack development under different dry-wetting cycle conditions, and have broad application prospects.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and replacements made within the spirit and principles of the present invention Improvements, etc., should be included within the protection scope of the present invention.

Claims (5)

1. A fine grained soil consolidation expansion and shrinkage and dry-wet cycle integrated test device is characterized by comprising an outer ring container (7) for simulating temperature, humidity and wind speed conditions; the outer ring container (7) is of a cavity structure and is provided with an air inlet pipe (71) with a first valve (11a) and an air outlet pipe (72) with a second valve (11b), the air inlet pipe (71) is connected with a temperature, humidity and air speed controller (15), an annular inner ring container (8) for applying lateral pressure is arranged on the bottom surface inside the outer ring container (7), and a lower permeable plate (6) is arranged in an open area formed inside the inner ring container (8); a sample (5) is arranged above the lower porous plate (6), an upper porous plate (4), a pressurizing base (2) and a top cover (1) are sequentially arranged on the top surface of the sample (5) from bottom to top, a plurality of displacement sensors (20) in a non-load state are arranged on the lower end surface of the top cover (1), the upper end surface of the pressurizing base (2) is connected with an external pressurizing mechanism, a pressure sensor (18) and a displacement sensor (19) in a load state are arranged on the pressurizing base (2), a temperature, humidity and wind speed sensor (21) is arranged on the inner wall of the outer ring container (7), water content sensors (22) are arranged around the sample (5), various sensors, displacement meters and cameras (24) are connected with a multi-channel data acquisition instrument (16), and signals of the multi-channel data acquisition instrument (16) are connected with a computer processing system (17) through data lines;

the inner ring container (8) comprises a rigid multi-cavity structure (25), the multi-cavity structure comprises an upper cavity (27), a middle cavity (28) and a lower cavity (29) which are sequentially arranged from top to bottom, one ends of the upper cavity (27), the middle cavity (28) and the lower cavity (29) close to the sample (5) are both open structures and are respectively coated with independent rubber films in sealing connection, and an outer rubber film (26d) which is directly contacted with the sample (5) is further arranged between the multi-cavity structure and the sample (5); the middle cavity (28) is connected with the first pressurizing pipeline (9), the upper cavity (27) and the lower cavity (29) are connected with the second pressurizing pipeline (30), and the multi-cavity structure can be filled with water to apply lateral pressure to a sample.

2. The fine soil consolidation swelling and shrinking and dry-wet cycle integrated test device according to claim 1, wherein the temperature, humidity and wind speed controller (15) comprises a heater (12) for adjusting air temperature, a humidifier (13) for adjusting air humidity and a fan (14) for adjusting air flow rate.

3. The fine soil consolidation shrinkage and dry-wet cycle integrated test device according to claim 1, wherein the upper cavity (27) and the lower cavity (29) are protection cavities, the middle cavity (28) is a measurement cavity, and the height of the middle cavity is not more than the height of the shrinkage limit of the sample.

4. The fine soil consolidation shrinkage and dry-wet cycle integrated test device according to claim 1, wherein the upper permeable plate (4) and the lower permeable plate (6) are made of alumina or a metal material which is not corroded, the permeability coefficient of the upper permeable plate is not larger than that of a sample, and the diameter of the upper permeable plate is 0.2-0.5 mm smaller than that of the sample.

5. The fine soil consolidation swelling and shrinking and dry-wet cycle integrated test device according to claim 2, characterized in that the moisture content sensor (22) comprises three probes, the three probes are distributed around the sample (5) at equal intervals and are positioned between the sample (5) and the rubber membrane (26), one side of the moisture content sensor is in close contact with the sample (5) under the confining pressure applied by the inner ring container (8), and the volume moisture content of the sample is measured, and the measurement range is 0-100%.

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