CN108362728A - A kind of cold area's Modified soil three-dimensional swell-shrink deformation indoor test system - Google Patents

Abstract

The invention relates to an indoor test system for three-dimensional expansion and contraction deformation of modified soil in cold regions. The four corrective feet on the bottom of the base can be adjusted to make the bottom of the base horizontal by adjusting the four corrective feet under the bottom of the base. The form of arrangement is respectively welded and fixed on the middle reference column of the peripheral frame; the four side panels for measuring deformation are corresponding to each other, and are respectively connected with the fixed bracket through the slider and the two crossed slide rails. It is an inseparable whole, in which the side panels are of a grid structure; the invention can simulate the three-dimensional expansion and contraction deformation of embankment soil in cold regions under temperature changes, and the test integrity is good, the operation is simple, and the application range is wide. It can be adjusted according to soil type, moisture content and compactness.

Description

An indoor test system for three-dimensional expansion and contraction deformation of modified soil in cold regions

technical field

The invention relates to a rock soil test system, which is specially suitable for indoor testing of three-dimensional frost heave rate of embankment modified soil in cold regions.

Background technique

A large number of high-grade highways and railways and other line projects inevitably pass through seasonal frozen soil areas and areas with large temperature differences between day and night. Adhering to the principle of "getting materials locally", some rock and soil materials need to be modified for use in embankments. Filling, such as adding cement to aeolian sand and other materials to modify the embankment project, but the embankment project after this modification will expand and shrink during the freeze-thaw process, and many unfavorable engineering geological problems such as cracks and thawing will appear. , Bringing many hidden dangers to projects in cold regions. Therefore, to simulate the outdoor environment, it is particularly important to test the three-dimensional expansion and contraction deformation of the modified soil in the cold region under the freeze-thaw state. At present, the measurement of indoor expansion and contraction of soil mainly focuses on one-dimensional and two-dimensional devices, that is, assuming that the sample is flat and ignoring the influence of the three-dimensional sample itself, such as patent CN203755286U, which can only measure Frost heave changes in the vertical direction are only measured and the data is not complete; another example is the patent CN202057647U. Although the patent integrates measurement and refrigeration, the temperature is not easy to control, and it is limited to negative temperatures, and the use of Freon refrigeration does not conform to the concept of environmental protection. The soil in cold regions, especially embankment filling in cold regions, is not only affected by one-dimensional or two-dimensional temperature changes, but mostly in a three-dimensional temperature environment, and its freeze-thaw deformation is in a three-dimensional state. The patent of the present invention provides an indoor test device for measuring the three-dimensional expansion and contraction deformation of soil in cold regions, which solves the problem that the three-dimensional frost heave rate of soil cannot be measured in the current indoor state, and provides an important basis for the construction of high-grade line projects in cold regions scientific basis.

Contents of the invention

In order to measure the three-dimensional expansion-contraction deformation of soil in cold regions under freeze-thaw state, the present invention provides an indoor test device for measuring three-dimensional expansion-contraction deformation of soil in cold regions. The device can effectively measure the three-dimensional expansion-contraction rate of indoor soil.

The technical solution adopted by the present invention to solve its technical problems is:

An indoor test system for three-dimensional expansion and contraction deformation of modified soil in cold regions, characterized in that:

The outer edge of the base bottom plate is equipped with front level bubbles and side level bubbles respectively, and four corrective feet are arranged under the base bottom plate to keep the base bottom plate in a horizontal state.

The four corrective feet under the base plate can be adjusted to make the base plate in a horizontal state;

Two slide rails are arranged under the center of the bottom plate of the base, arranged in a criss-cross pattern, respectively welded and fixed on the middle datum column of the peripheral frame;

The four side panels for measuring deformation are corresponding to each other, and are respectively connected with the fixed bracket through the slider and the two cross slide rails, and are connected as an inseparable whole, in which the side panels are of grid structure;

Before the test, rigidly connect the two side panels with the upper slide rail bracket (5), and make this part slidingly connected with the upper slide rail (9) through the upper slide rail slider (7), and the upper slide rail spring (11) Installed between the two upper slide rail sliders (7), mark three sets of symmetrical planes on the sample (22), namely upper and lower, front and rear, and left and right respectively, and paste the strain gauges on the center of the front and rear symmetrical sides. After the knot is firm, place the sample (22) on the base plate (15), ensure that the side plate (20) is fully in contact with the left and right sides of the sample (22), and measure the average accumulation within 2 minutes of 20 reciprocating Strain ≤ 50με, write down the elastic coefficient and connection length of the spring at this time; similarly, connect the other two side plates to the lower rail bracket (6) rigidly, and pass this part through the lower rail slider (8) and the lower rail bracket (8). The rails (10) are slidingly connected, and the lower rail spring (12) is installed between the two lower rail sliders (8). The elastic coefficient and connection length of the lower rail spring (12) are consistent with the upper rail spring (11). .

Further, the material of the side plate is an aluminum plate with a large thermal conductivity. At the same time, the peripheral side length of the plate is smaller than the side length of the sample, the side of the bottom plate is longer than the side length of the test piece, and the material of the bottom plate is Invar with a small thermal conductivity.

When the temperature drops, the sample freezes and shrinks, and the side plate is tightly attached to the sample by virtue of the elastic recovery force, and the shrinkage deformation is measured; when the temperature rises, the sample expands;

Place the standard sample (22) on the center of the base bottom plate (15), make the four side panels in precise contact with it, put one end of the telescopic head of the four side sensors close to the contact area of the side panel, and place the side panels The tail end of the sensor is fixed on the middle reference column (18) of the peripheral frame, the upper mounting plate (19) is placed, one end of the telescopic head of the upper sensor is closely attached to the contact area of the upper mounting plate (19), and the tail end of the upper sensor is fixed on the periphery The frame upper cover (16) center is placed on the peripheral frame upper cover, and the five sensor telescopic heads are compressed to half of their length by adjusting the fixed ends of the five tails, so as to ensure that the deformation can be effectively recorded during expansion and contraction;

Put the three-dimensional testing device into the freeze-thaw environment chamber. When the temperature rises, the sample expands and deforms, causing the side plate to slide on the upper and lower rails. At this time, the side sensor measures the small horizontal displacement of the plate. , to measure the expansion and deformation of the sample in two horizontal directions, and the upper plate will produce vertical displacement under the action of expansion force to measure the expansion and deformation of the sample in the vertical direction; when the temperature decreases, the sample shrinks and deforms , through the horizontal elastic recovery force of the spring between the sliders, the side plate is in close contact with the sample, and the sensor measures the shrinkage horizontal displacement of the plate to measure the shrinkage deformation of the sample in two horizontal directions, and the upper plate will be in Under the action of gravity, it is displaced downward, and the shrinkage deformation of the sample in the vertical direction is measured.

The beneficial effects of the present invention are:

It can simulate the three-dimensional expansion and contraction deformation of embankment soil in cold regions indoors under temperature changes. The test has good integrity, easy operation and wide application range. It can be carried out according to different types of test pieces such as soil type, moisture content and compactness. Two-way elastic adjustment, continuous collection of expansion and contraction deformation data under different freeze-thaw cycles, different freeze-thaw temperatures and different freeze-thaw rates, with high precision and good execution rate. Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is further described:

Fig. 1 is a structural representation of the present invention

Fig. 2 is the front view of the present invention

Fig. 3 is a side view of the present invention

Fig. 4 is the top view of the present invention

Fig. 5 is the base bottom plate of the present invention

Fig. 6 is the testing device of the present invention

Fig. 7 is a sectional view of the present invention

Structure description:

In the figure 1. Upper sensor, 2. Side sensor, 3. Fixed end of upper sensor, 4. Fixed end of side sensor, 5. Upper rail bracket, 6. Lower rail bracket, 7. Upper rail slider 8. Lower rail slider, 9. Upper rail, 10. Lower rail, 11 Upper rail spring, 12. Lower rail spring, 13. Front level bubble, 14. Side level bubble, 15. Base plate, 16. Periphery Frame upper cover, 17. Peripheral frame, 18. Middle reference column, 19. Upper plate, 20. Side plate, 21. Correction foot column, 22. Sample

Detailed ways:

The outer edge of the bottom plate of the base is equipped with the front level bubble and the side level bubble respectively, and the four correction feet under the base bottom plate can be adjusted to make the base bottom plate in a horizontal state; in order to ensure that the device simultaneously measures the lateral two-way deformation , two slide rails are arranged under the center of the bottom plate of the base, which are arranged in a criss-cross pattern, respectively welded and fixed on the middle datum column of the peripheral frame; It is connected with the fixed bracket through the slider and the smooth upper and lower rails, and the connection is an inseparable whole. The main feature of the side panel is the grid structure. The material is an aluminum plate with a high thermal conductivity. The grid width is 20mm and the thickness It is 2mm, which can not only ensure the coordination of deformation between the sample and the board, but also ensure that the temperature can be transmitted well. Length = (the side length of the sample - 20mm), in order to ensure that the sample does not hang in the air when it expands and deforms, the side length of the bottom plate = (the side length of the test piece + 10mm), to simulate the relatively closed heat transfer environment of the lower side of the embankment soil, the thickness of the bottom plate is 20mm, the material is Invar with small thermal conductivity; between the two sliders in the smooth guide rail, a spring with small elastic coefficient is installed. The special feature of this spring is that when the sample is installed, the spring is in tension, There is a certain tension between the two sliders to ensure full contact between the board and the sample, but the sample cannot produce excessive strain under the action of two-way board extrusion, that is, during the test, when the test board is not arranged Paste transverse strain gauges (BX120-60AA) on both sides of the sample to ensure that the average cumulative strain in 2 minutes of 20 reciprocating measurements is less than or equal to 50με. When the temperature drops, the sample freezes and shrinks, and the side plate is tightly attached to the sample by virtue of the elastic recovery force, and the shrinkage deformation is measured; when the temperature rises, the sample expands, and the spring has a greater influence on the temperature deformation of the sample Small, in the same way, repeat the above spring installation steps in the lower rail; put one end of the side sensor close to the sensing area of the side panel, and reserve enough telescopic length, and fix the end of the sensor on the middle reference column of the peripheral frame Above, fix the tail of the sensor through the fixed end of the side sensor on the middle reference column, put the standard sample into the three-dimensional expansion and contraction deformation measurement device, place the upper plate, and install the upper sensor on the sensor fixed end of the upper plate Place the upper cover of the peripheral frame. In order to improve the applicability of the test system to high and low temperatures and make the simulated environment more realistic, the sensor uses a low temperature resistant sensor (-30°C), a two-way retractable side head, and a range of 5mm. Put the three-dimensional testing device into the freeze-thaw environment chamber. When the temperature rises, the sample expands and deforms, causing the side plate to slide on the upper and lower slide rails. At this time, the sensor measures the small displacement of the plate to determine Expansion and deformation of the sample; when the temperature drops, the sample undergoes freezing and shrinkage deformation, through the elastic recovery force of the spring between the sliders, the side plate is in close contact with the sample, and the sensor measures the shrinkage displacement of the plate to measure the sample When testing the three-dimensional deformation law of the specimen under multiple freeze-thaw conditions, the test system can ensure the continuity of the test data and the integrity of the test specimen.

In Fig. 5, on the base plate (15), adjust the four correcting feet (21), so that the front level bubble (13) on the outer edge of the base plate (15) is centered, and at the same time, the side level bubble (14) Center it so that the base plate (15) is in a horizontal state.

In Fig. 6, the side panel (20) is rigidly connected with the upper slide rail support (5), and this part is slidably connected with the upper slide rail (9) through the upper slide rail slider (7). Install the upper rail spring (11) between the two upper rail sliders (7); similarly, the side plate (20) is rigidly connected to the lower rail bracket (6), and slide this part through the lower rail The block (8) is slidably connected with the lower rail (10), and the lower rail spring (12) is installed between the two lower rail sliders (8).

In Fig. 7, the upper and lower slide rails (9), (10) are arranged in a criss-cross pattern, and are respectively rigidly connected to the middle reference column (18); the side sensors (2) are connected to the middle reference column (18) and fix it with the side sensor fixing end (4). Put the upper plate (19) on the top of the sample, and make the upper sensor (1) closely contact with the upper plate (19), and fix it on the upper cover (16) of the peripheral frame with the fixed end of the upper sensor (3), so that The overall external frame is closed.

The working process is as follows:

Place the soil sample (22) in the center of the base bottom plate (15), make the side panels (20) closely fit the sample (22), and place the upper panel (19) in the center of the sample (22) , and connect each part of the sensor. Place the device as a whole in a freeze-thaw environment chamber. When the temperature rises or falls, when the sample expands or contracts, the upper plate (19) and the side plate (20) will move and place on it. The upper sensor (1) and side sensor (2) of the utility model will collect movement deformation, reflect the freeze-thaw deformation law of soil in cold regions, and provide quality assurance for the construction of high-grade cold region line projects.

Claims (3)

1. An indoor testing system for three-dimensional expansion and contraction deformation of modified soil in cold regions, characterized in that: The outer edge of the base bottom plate is equipped with front level bubbles and side level bubbles respectively, and four corrective feet are arranged under the base bottom plate to keep the base bottom plate in a horizontal state. The four corrective feet under the base plate can be adjusted to make the base plate in a horizontal state; Two slide rails are arranged under the center of the bottom plate of the base, arranged in a criss-cross pattern, respectively welded and fixed on the middle datum column of the peripheral frame; The four side panels for measuring deformation are corresponding to each other, and are respectively connected with the fixed bracket through the slider and the two cross slide rails, and are connected as an inseparable whole, in which the side panels are of grid structure; Before the test, rigidly connect the two side panels with the upper slide rail bracket (5), and make this part slidingly connected with the upper slide rail (9) through the upper slide rail slider (7), and the upper slide rail spring (11) Installed between the two upper slide rail sliders (7), mark three sets of symmetrical planes on the sample (22), namely upper and lower, front and rear, and left and right respectively, and paste the strain gauges on the center of the front and rear symmetrical sides. After the knot is firm, place the sample (22) on the base plate (15), ensure that the side plate (20) is fully in contact with the left and right sides of the sample (22), and measure the average accumulation within 2 minutes of 20 reciprocating Strain ≤ 50με, write down the elastic coefficient and connection length of the spring at this time; similarly, connect the other two side plates to the lower rail bracket (6) rigidly, and pass this part through the lower rail slider (8) and the lower rail bracket (8). The rails (10) are slidingly connected, and the lower rail spring (12) is installed between the two lower rail sliders (8). The elastic coefficient and connection length of the lower rail spring (12) are consistent with the upper rail spring (11). . 2. The system according to claim 1, characterized in that: the material of the side panel is an aluminum plate with a large thermal conductivity; at the same time, the peripheral side length of the panel is smaller than the side length of the sample, the side of the bottom plate is larger than the side length of the test piece, and the material of the bottom plate Invar with low thermal conductivity. 3. The method of applying the system as claimed in claim 1 or 2, characterized in that: when the temperature drops, the sample freezes and shrinks, and the side plate is closely attached to the sample by virtue of the elastic recovery force, and the shrinkage deformation is measured ; When the temperature rises, the sample expands; Place the standard sample (22) on the center of the base bottom plate (15), make the four side panels in precise contact with it, put one end of the telescopic head of the four side sensors close to the contact area of the side panel, and place the side panels The tail end of the sensor is fixed on the middle reference column (18) of the peripheral frame, the upper mounting plate (19) is placed, one end of the telescopic head of the upper sensor is closely attached to the contact area of the upper mounting plate (19), and the tail end of the upper sensor is fixed on the periphery The frame upper cover (16) center is placed on the peripheral frame upper cover, and the five sensor telescopic heads are compressed to half of their length by adjusting the fixed ends of the five tails, so as to ensure that the deformation can be effectively recorded during expansion and contraction; Put the three-dimensional testing device into the freeze-thaw environment chamber. When the temperature rises, the sample expands and deforms, causing the side plate to slide on the upper and lower rails. At this time, the side sensor measures the small horizontal displacement of the plate. , to measure the expansion and deformation of the sample in two horizontal directions, and the upper plate will produce vertical displacement under the action of expansion force to measure the expansion and deformation of the sample in the vertical direction; when the temperature decreases, the sample shrinks and deforms , through the horizontal elastic recovery force of the spring between the sliders, the side plate is in close contact with the sample, and the sensor measures the shrinkage horizontal displacement of the plate to measure the shrinkage deformation of the sample in two horizontal directions, and the upper plate will be in Under the action of gravity, it is displaced downward, and the shrinkage deformation of the sample in the vertical direction is measured.