An in-situ testing device for swelling parameters of expansive soil

Abstract

The present invention belongs to the field of soil layer measurement, and discloses an in-situ testing device for the expansive parameters of expansive soil, including an upper top plate, a plurality of water injection pipes, a reaction plate, and a plurality of displacement meters. A plurality of water injection pipe mounting holes are provided on the upper top plate; one end of the plurality of water injection pipes is respectively connected to the plurality of water injection pipe mounting holes, and a plurality of water injection holes are provided on the other end side walls; and one end of the water injection pipe is connected to the opening of the water injection pipe mounting hole; one end of the plurality of displacement meters is connected to the reaction plate, and the other end is connected to the upper top plate. An upper top plate and a plurality of water injection pipes are provided, and then the testing device is fixed in the in-situ expansive soil layer through the plurality of water injection pipes. During water injection, the water injection pipes play a good anchoring role due to the expansion of the soil layer. At the same time, the reaction plate fits the surface of the expansive soil layer, and the expansion of the expansive soil layer is characterized by measuring the displacement of the reaction plate, thereby realizing the in-situ measurement of the expansive parameters of the expansive soil layer, so that the measured value is as close to the actual situation as possible.

Description

Technical Field

[0001] The invention belongs to the field of soil layer measurement and relates to an in-situ testing device for swelling parameters of expansive soil. Background Art

[0002] Atmospheric influence depth refers to the effective depth of soil deformation caused by precipitation, evaporation, ground temperature and other factors under the influence of natural climate. The expansive soil layer within this range is easily affected by the environment and has a great impact on the project. Therefore, it is very important to clarify the expansive parameters of the expansive soil layer within the atmospheric influence depth for the design of building structures. At present, the expansive parameters of the expansive soil layer are basically measured in the laboratory, that is, after the soil samples are taken out of the drilling hole, their expansive parameters are measured under the condition of saturation with water and limiting the deformation of the soil samples.

[0003] Although this method is simple and easy to implement, it is difficult to perform due to the following reasons: 1. The soil sample is disturbed and the expansion deformation is released; 2. The indoor test uses segmented sampling and cannot fully represent the entire soil layer; 3. The moisture content of the soil sample caused by full immersion and saturation is different from that caused by on-site immersion and penetration; 4. The indoor deformation is a lateral limit condition, while the in-situ deformation is a three-dimensional stress state; 5. Indoor tests cannot accurately obtain the soil wetting deformation and expansion force deformation process; which often leads to large differences between the measured values ​​of the expansion parameters and the actual situation on site. Summary of the invention

[0004] The purpose of the present invention is to overcome the disadvantage that the measured values ​​of the expansion parameters in the above-mentioned prior art are often greatly different from the actual situation on site, and to provide an in-situ testing device for the expansion parameters of expansive soil.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In one aspect of the present invention, an in-situ testing device for expansive soil expansion parameters comprises:

[0007] An upper top plate, wherein a plurality of water injection pipe installation holes are provided on the upper top plate;

[0008] A plurality of water injection pipes, one end of each of which is connected to a plurality of water injection pipe mounting holes, and a plurality of water injection holes are provided on the side wall of the other end; and one end of each of the water injection pipes connected to the water injection pipe mounting hole is open;

[0009] reaction plate; and

[0010] A plurality of displacement meters, each of which has one end connected to the reaction plate and the other end connected to the upper plate;

[0011] When in use: one end of the plurality of water injection pipes away from the upper top plate is inserted into the expansive soil layer, the reaction plate is located between the upper top plate and the surface of the expansive soil layer, and the surface of the reaction plate is in contact with the surface of the expansive soil layer; the displacement meter is used to measure the displacement of the reaction plate.

[0012] The test device of the present invention is further improved in that:

[0013] The distance between two adjacent water injection holes gradually increases in the direction away from the upper top plate.

[0014] It also includes: a water pumping pipe, one end of which passes through the reaction plate and is connected to the water pumping pipe installation hole opened on the upper top plate, and the other end is provided with a plurality of water pumping holes; and one end of the water pumping pipe and the water pumping pipe installation hole are open; when in use: the end of the water pumping pipe away from the upper top plate is inserted into the expansive soil layer.

[0015] The distance between two adjacent water pumping holes gradually decreases in the direction away from the upper top plate.

[0016] The diameter of the reaction disk is greater than the atmospheric influence depth.

[0017] It also includes: a plurality of moisture sensors; when in use: the plurality of moisture sensors are arranged at intervals from top to bottom in the expansive soil layer below the reaction disk.

[0018] The ends of the plurality of water injection pipes away from the upper top plate are arranged as pointed ends.

[0019] Another aspect of the present invention is an in-situ testing device for expansive soil parameters, comprising:

[0020] An upper top plate, wherein a plurality of water injection pipe installation holes are provided on the upper top plate;

[0021] A plurality of water injection pipes, one end of each of which is connected to a plurality of water injection pipe mounting holes, and a plurality of water injection holes are provided on the side wall of the other end; and one end of each of the water injection pipes connected to the water injection pipe mounting hole is open;

[0022] Reaction plate;

[0023] A plurality of displacement meters, each of which has one end connected to the reaction plate and the other end connected to the upper plate; and

[0024] A spring assembly, one end of which is connected to the reaction plate, and the other end of which is connected to the upper plate;

[0025] When in use: one end of the plurality of water injection pipes away from the upper top plate is inserted into the expansive soil layer, the reaction plate is located between the upper top plate and the surface of the expansive soil layer, and the surface of the reaction plate is in contact with the surface of the expansive soil layer, and the displacement meter is used to measure the displacement of the reaction plate.

[0026] The test device of the present invention is further improved in that:

[0027] It also includes: a water pumping pipe, one end of which passes through the reaction plate and is connected to the water pumping pipe installation hole opened on the upper top plate, and the other end is provided with a plurality of water pumping holes; and one end of the water pumping pipe and the water pumping pipe installation hole are open; when in use: the end of the water pumping pipe away from the upper top plate is inserted into the expansive soil layer.

[0028] The spring assembly includes a plurality of springs, one end of each of the plurality of springs is connected to the reaction disk, and the other end of each of the springs is connected to the upper top disk.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] By setting an upper top plate, setting a number of water injection pipe installation holes on the upper top plate, fixing a number of water injection pipes through the number of water injection pipe installation holes, and then installing the number of water injection pipes inside the in-situ expansive soil layer, the water injection pipes play a good anchoring role due to the expansion of the expansive soil during water injection. At the same time, the reaction plate fits the surface of the expansive soil layer, and the displacement of the reaction plate is measured by the displacement meter to characterize the expansion of the expansive soil layer, so as to achieve in-situ measurement of the expansive parameters of the expansive soil layer, and there is no need to collect soil samples back to the laboratory for measurement, which effectively overcomes various defects of laboratory measurement and makes the measurement value as close to the actual situation as possible. At the same time, a number of displacement meters are set, and the expansion is calculated by the average of the number of displacement meters, which effectively reduces the measurement error.

[0031] Furthermore, the distance between two adjacent water injection holes of the plurality of water injection holes gradually increases in the direction away from the upper top plate, so as to fully simulate the step-by-step infiltration of actual precipitation, so that the measured expansion parameters are closer to the actual situation.

[0032] Furthermore, it also includes a pumping pipe. On the one hand, through the pumping force of the pumping pipe, a certain negative pressure is maintained in the center of the expansive soil layer, so that the water injected by the water injection pipe can quickly seep into the expansive soil layer, so that the expansive soil layer is quickly saturated with water, shortening the test time and improving work efficiency. On the other hand, the design of the pumping pipe effectively prevents water from seeping into the soil below the atmospheric influence depth, which in turn causes errors in the measurement results, so that the water can only saturate the expansive soil layer within the atmospheric influence depth as much as possible, thereby minimizing the measurement error.

[0033] Furthermore, the distance between two adjacent pumping holes gradually decreases in the direction away from the upper top plate, so that water can saturate the expansive soil layer within the atmospheric influence depth as much as possible.

[0034] Furthermore, the diameter of the reaction disk is larger than the atmospheric influence depth. Since too small a size will cause severe stress concentration at the edge of the reaction disk, this force may damage the test soil and cause measurement failure. When the horizontal diameter is larger than the vertical depth, it is believed in engineering practice that in this case the stress concentration is weak and the measurement is carried out normally.

[0035] Furthermore, it also includes a plurality of moisture sensors, through which the current moisture content at each depth in the expansive soil layer can be obtained in real time, so as to carry out combined statistics and analysis between the moisture content and the expansiveness parameter, and at the same time, know whether the current expansive soil layer is already saturated with water.

[0036] Furthermore, the ends of the plurality of water injection pipes away from the upper top plate are arranged as pointed ends, so as to facilitate fixing the water injection pipes in the expansive soil layer.

[0037] Furthermore, a spring assembly is provided, one end of which is connected to the reaction plate, and the other end is connected to the upper top plate. The expansion force of the expansive soil layer can be calculated through the displacement of the reaction plate and the stiffness coefficient of the spring assembly, thereby realizing in-situ expansion force measurement of the expansive soil layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a front view of the testing device in the first embodiment of the present invention;

[0039] Figure 2 It is a front view of a testing device in a second embodiment of the present invention;

[0040] Figure 3 FIG. 4 is a top view of a testing device in a second embodiment of the present invention.

[0041] Among them: 1-bolt; 2-upper top plate; 3-water injection pipe; 4-displacement meter; 5-spring; 6-reaction plate; 7-water extraction pipe; 8-water injection hole; 9-water extraction hole; 10-water sensor. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0045] See also Figure 1 In the first embodiment of the present invention, an in-situ testing device for the expansive parameters of expansive soil is disclosed, and the testing device includes an upper top plate 2, a plurality of water injection pipes 3, a reaction plate 6, and a plurality of displacement meters 4. The upper top plate 2 is provided with a plurality of water injection pipe mounting holes; one end of the plurality of water injection pipes 3 is respectively connected to the plurality of water injection pipe mounting holes, and the other end side walls are provided with a plurality of water injection holes 8; and, the water injection pipes 3 are connected to the opening of one end of the water injection pipe mounting holes; one end of the plurality of displacement meters 4 is connected to the reaction plate 6, and the other end is connected to the upper top plate 2. And, when in use: one end of the plurality of water injection pipes 3 away from the upper top plate 2 is inserted into the expansive soil layer, the reaction plate 6 is located between the upper top plate 2 and the surface of the expansive soil layer, and the surface of the reaction plate 6 is in contact with the surface of the expansive soil layer; the displacement meter 4 is used to measure the displacement of the reaction plate 6.

[0046] Specifically, the water injection pipe 3 and the water injection pipe mounting hole can be fixedly connected by bolts 1. The water injection pipe 3 generally uses a hollow steel pipe, and water is injected into the expansive soil layer by connecting the water supply equipment at the open end. In this embodiment, 6 water injection pipe mounting holes are set, and they are evenly distributed along the outer circumference of the upper top plate 2, but it is not limited to this. Other numbers and arrangements are also possible. At the same time, 6 water injection pipes 3 are also designed adaptively, and the evenly arranged method ensures that the expansive soil layer is evenly injected with water.

[0047] At the same time, during the water injection process, the surrounding expansive soil expands when it encounters water, and the expansion force will "squeeze" the water injection pipe 3. Sufficient pressure helps to anchor the equipment. The water injection pipe 3 plays an anchoring role while injecting water.

[0048] Preferably, the plurality of water injection holes 8 are arranged densely on top and sparsely on the bottom, that is, the spacing between two adjacent water injection holes 8 gradually increases in the direction away from the upper top plate 2, so as to fully simulate the step-by-step infiltration of actual precipitation, so that the measured expansion parameters are closer to the actual situation.

[0049] Preferably, it also includes a pumping pipe 7, one end of which passes through the reaction plate 6 and is connected to the pumping pipe mounting hole opened on the upper top plate 2, and the other end is provided with a plurality of pumping holes 9; and one end of the pumping pipe 7 and the pumping pipe mounting hole are open; when in use: the end of the pumping pipe 7 away from the upper top plate 2 is inserted into the expansive soil layer.

[0050] On the one hand, through the suction effect of the pumping pipe 7, a certain negative pressure is maintained in the center of the expansive soil layer, so that the water injected by the water injection pipe 3 can quickly seep into the expansive soil layer, so that the expansive soil layer is quickly saturated with water, shortening the test time and improving work efficiency. In this embodiment, the pumping pipe 7 is arranged in the middle of a plurality of water injection pipes 3, so that the negative pressure in the expansive soil layer can be uniform, the seepage speed in each direction is roughly equal, and it is as close as possible to the actual rainfall seepage situation, so as to improve the accuracy of the measurement result.

[0051] On the other hand, the design of the pumping pipe 7 effectively prevents water from seeping into the soil below the atmospheric influence depth, which would lead to errors in the measurement results. It allows water to saturate the expansive soil layer within the atmospheric influence depth as much as possible, thereby minimizing the error between the measurement results and the actual situation.

[0052] Preferably, the distance between two adjacent pumping holes 9 gradually decreases in the direction away from the upper top plate 2, so that water can saturate the expansive soil layer within the atmospheric influence depth as much as possible.

[0053] Preferably, the diameter of the reaction disk 6 is greater than the atmospheric influence depth.

[0054] Too small a size will cause severe stress concentration at the edge of the reaction plate, which may damage the test soil and cause the test to fail. When the horizontal diameter is greater than the vertical depth, it can be considered in engineering practice that the stress concentration is weak in this case, so this design is adopted.

[0055] Preferably, it further comprises a plurality of moisture sensors 10; when in use: the plurality of moisture sensors 10 are arranged at intervals from top to bottom in the expansive soil layer below the reaction plate 6. The moisture sensors 10 can be used to obtain the current moisture content at each depth position in the expansive soil layer in real time, so as to perform statistics and analysis on the combination of moisture content and expansibility parameters, and at the same time, to know whether the current expansive soil layer is already saturated with water.

[0056] Preferably, the ends of the plurality of water injection pipes 3 away from the upper top plate 2 are configured as pointed ends, so as to facilitate fixing the water injection pipes 3 in the expansive soil layer.

[0057] The specific working process of the in-situ test device for the expansive parameters of expansive soil in this embodiment is described by taking the expansive soil layer at the atmospheric influence depth as an example. The test object is a cylindrical expansive soil body surrounded by the water injection pipe 3 and the atmospheric influence depth surface, whose height is the atmospheric influence depth and the bottom area is the area of ​​the reaction plate 6. In addition, in order to reduce the influence of the boundary effect, the diameter of the device should be greater than the atmospheric influence depth, and the test soil body is an oblate cylinder:

[0058] Step 1: Select a suitable test site, use drilling equipment to drill a hole with a depth of about the atmospheric impact depth and a diameter of about the diameter of the pumping pipe 7, wrap the moisture sensor 10 with in-situ expansive soil, and measure its dry density, place a moisture sensor 10 in the borehole at each distance; put the pumping pipe 7 into the borehole, backfill with expansive soil and compact it.

[0059] Step 2: Drive several water injection pipes 3 according to the preset arrangement, install the top plate 2, and fix the water injection pipes 3 with bolts 1, install the displacement meter 4 and the reaction plate 6, and place the reaction plate 6 close to the surface of the expansive soil layer.

[0060] Step 3: Install the top plate 2.

[0061] Step 4: Connect the water injection pipe 3 to the water supply equipment, connect the water suction pipe 7 to the water pumping equipment, and adjust the displacement meter 4 to zero.

[0062] Step 5: Turn on the power supply to start the pumping and water supply equipment, record the readings of the moisture sensor 10 and the displacement meter 4 at each time and organize the data after the test. The expansion amount corresponding to the expansive soil layer can be calculated based on the average value of the displacement meter 4 readings at each time and the area of ​​the reaction plate 6.

[0063] In the second embodiment of the present invention, an in-situ testing device for the swelling parameters of expansive soil is disclosed, and the testing device includes an upper top plate 2, a plurality of water injection pipes 3, a reaction plate 6, a plurality of displacement meters 4, and a spring assembly. When in use: the ends of the plurality of water injection pipes 3 away from the upper top plate 2 are inserted into the expansive soil layer, the reaction plate 6 is located between the upper top plate 2 and the surface of the expansive soil layer, and the surface of the reaction plate 6 is in contact with the surface of the expansive soil layer, and the displacement meter 4 is used to measure the displacement of the reaction plate 6.

[0064] The spring assembly includes a plurality of springs 5, one end of each of the plurality of springs 5 ​​is connected to the reaction plate 6, and the other end is connected to the upper plate 2. The spring 5 is a spring with a large spring coefficient, and the displacement can be regarded as zero within the allowable error range to minimize the change in expansion force caused by the deformation of the expansive soil layer.

[0065] According to the average value of the readings of the four displacement meters, plus the known stiffness coefficient, the expansion force of the expansive soil layer can be obtained. The formula is as follows:

[0066]

[0067] Where, F is the expansion force of the expansive soil layer, k is the stiffness coefficient of spring 5, is the average reading of displacement meter 4.

[0068] The specific working process of the in-situ test device for the expansive parameters of expansive soil in this embodiment is described by taking the expansive soil layer at the atmospheric influence depth as an example. The test object is a cylindrical expansive soil body surrounded by the water injection pipe 3 and the atmospheric influence depth surface, whose height is the atmospheric influence depth and the bottom area is the area of ​​the reaction plate 6. In addition, in order to reduce the influence of the boundary effect, the diameter of the device should be greater than the atmospheric influence depth, and the test soil body is an oblate cylinder:

[0069] Step 1: Select a suitable test site, use drilling equipment to drill a hole with a depth of about the atmospheric impact depth and a diameter of about the diameter of the pumping pipe 7, wrap the moisture sensor 10 with in-situ expansive soil, and measure its dry density, place a moisture sensor 10 in the borehole at each distance; put the pumping pipe 7 into the borehole, backfill with expansive soil and compact it.

[0070] Step 2: Drive several water injection pipes 3 according to the preset arrangement, install the top plate 2, and fix the water injection pipes 3 with bolts 1, install the displacement meter 4, spring assembly, reaction plate 6, and place the reaction plate 6 close to the surface of the expansive soil layer.

[0071] Step 3: Install the top plate 2.

[0072] Step 4: Connect the water injection pipe 3 to the water supply equipment, connect the water suction pipe 7 to the water pumping equipment, and adjust the displacement meter 4 to zero.

[0073] Step 5: Turn on the power supply to start the pumping equipment and water supply equipment, record the readings of the moisture sensor 10 and the displacement meter 4 at each moment and organize the data after the test.

[0074] Step 6: The average value of the displacement at each moment recorded by the displacement meter 4 According to the formula The expansion force of the expansive soil layer at each moment can be calculated.

[0075] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An in-situ testing device for the swelling parameters of expansive soil, characterized in that: include: An upper top plate (2), wherein a plurality of water injection pipe installation holes are provided on the upper top plate (2); A plurality of water injection pipes (3), one end of each of the plurality of water injection pipes (3) being connected to a plurality of water injection pipe mounting holes, and a plurality of water injection holes (8) being provided on the side walls of the other ends; and one end of each of the water injection pipes (3) being connected to the water injection pipe mounting hole is open; a reaction plate (6); and A plurality of displacement meters (4), wherein one end of each of the plurality of displacement meters (4) is connected to the reaction plate (6), and the other end of each of the plurality of displacement meters (4) is connected to the upper plate (2); When in use: one end of the plurality of water injection pipes (3) away from the upper top plate (2) is inserted into the expansive soil layer, the reaction plate (6) is located between the upper top plate (2) and the surface of the expansive soil layer, and the surface of the reaction plate (6) is in contact with the surface of the expansive soil layer; the displacement meter (4) is used to measure the displacement of the reaction plate (6); The plurality of water injection holes (8) are arranged such that the distance between two adjacent water injection holes (8) gradually increases in the direction away from the upper top plate (2); The ends of the plurality of water injection pipes (3) away from the upper top plate (2) are arranged as pointed ends.

2. The in-situ testing device for the swelling parameters of expansive soil according to claim 1, characterized in that: Also includes: A water pumping pipe (7), one end of the water pumping pipe (7) passes through the reaction plate (6) and is connected to a water pumping pipe mounting hole provided on the upper top plate (2), and the other end is provided with a plurality of water pumping holes (9); and one end of the water pumping pipe (7) and the water pumping pipe mounting hole are open; When in use: the end of the water pumping pipe (7) away from the upper top plate (2) is inserted into the expansive soil layer.

3. The in-situ testing device for the swelling parameters of expansive soil according to claim 2, characterized in that: The plurality of water pumping holes (9) are arranged in a direction away from the upper top plate (2), and the distance between two adjacent water pumping holes (9) gradually decreases.

4. The in-situ testing device for the swelling parameters of expansive soil according to claim 1, characterized in that: The diameter of the reaction disk (6) is greater than the atmospheric influence depth.

5. The in-situ testing device for the swelling parameters of expansive soil according to claim 1, characterized in that: Also includes: a plurality of moisture sensors (10); When in use: the plurality of moisture sensors (10) are arranged at intervals from top to bottom in the expansive soil layer below the reaction plate (6).

6. An in-situ testing device for the swelling parameters of expansive soil, characterized in that: include: An upper top plate (2), wherein a plurality of water injection pipe installation holes are provided on the upper top plate (2); A plurality of water injection pipes (3), one end of each of the plurality of water injection pipes (3) being connected to a plurality of water injection pipe mounting holes, and a plurality of water injection holes (8) being provided on the side walls of the other ends; and one end of each of the water injection pipes (3) being connected to the water injection pipe mounting hole is open; Reaction plate (6); A plurality of displacement meters (4), wherein one end of each of the plurality of displacement meters (4) is connected to the reaction plate (6), and the other end of each of the plurality of displacement meters (4) is connected to the upper plate (2); as well as A spring assembly, one end of which is connected to the reaction plate (6) and the other end of which is connected to the upper plate (2); When in use: one end of the plurality of water injection pipes (3) away from the upper top plate (2) is inserted into the expansive soil layer, the reaction plate (6) is located between the upper top plate (2) and the surface of the expansive soil layer, and the surface of the reaction plate (6) is in contact with the surface of the expansive soil layer, and the displacement meter (4) is used to measure the displacement of the reaction plate (6); Also includes: A water pumping pipe (7), one end of the water pumping pipe (7) passes through the reaction plate (6) and is connected to a water pumping pipe mounting hole provided on the upper top plate (2), and the other end is provided with a plurality of water pumping holes (9); and one end of the water pumping pipe (7) and the water pumping pipe mounting hole are open; When in use: one end of the water pumping pipe (7) away from the upper top plate (2) is inserted into the expansive soil layer; The spring assembly comprises a plurality of springs (5), one end of each of the plurality of springs (5) is connected to the reaction plate (6), and the other end of each of the plurality of springs (5) is connected to the upper plate (2).

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