Insertion-type expansive soil rainfall testing device and method

Abstract

The present invention provides an insertable expansive soil rainfall testing device and method, comprising: an insert rod; an earth pressure sensor; a water injection device; a water source supply device; and a control terminal. By installing an earth pressure sensor at the bottom of the insert rod and arranging a water injection device above the sensor, the device effectively simulates the stress response of expansive soil under rainfall conditions, accurately determining the expansion properties of the expansive soil layer on-site. This device also ensures that water uniformly penetrates the soil within the sensor's detection area, thereby improving the accuracy of stress measurement. Furthermore, the control terminal monitors and calculates the water injection volume and earth pressure in real time, enabling more accurate analysis of the physical and mechanical properties of the expansive soil and providing a reliable reference for related engineering and structural design.

Description

Technical Field

[0001] The present invention relates to the field of expansive soil performance testing, in particular to an insertable expansive soil rainfall testing device and a method thereof. Background Art

[0002] Expansive soils are widely distributed in my country, and their diseases are prominent, seriously impacting the speed of foundation construction and regional development in expansive soil areas. Currently, the expansion characteristics of expansive soils are generally determined according to specifications. However, this method is often conservative and fails to fully utilize the foundation's performance, leading to the adoption of large-scale reinforcement and strong support measures, which indirectly wastes resources. The expansiveness indicators of strata given in geological survey data or specifications often fail to reflect the actual stratum characteristics at the construction site, and the expansiveness indicators derived from laboratory methods often differ significantly from the actual foundation conditions. Therefore, accurately obtaining the expansiveness indicators of expansive soil strata under rainfall conditions is of great significance to both structural design and engineering construction. Therefore, an insertable expansive soil rainfall testing device and method are proposed to address the above issues. Summary of the Invention

[0003] The main purpose of the present invention is to provide an insertable expansive soil rainfall testing device and method, which can detect on-site the change law of the physical and mechanical parameters of the expansive soil under the action of water expansion, which can greatly promote the construction capacity of major projects, make greater contributions to economic development, and have broad application prospects.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: an insertable expansive soil rainfall testing device and method thereof, comprising:

[0005] Insertion rod for insertion into expansive soil;

[0006] The soil pressure sensor is set at the bottom of the insertion rod to detect the stress of the expansive soil;

[0007] A water injection device is provided inside the insertion rod and the water injection position is located above the soil pressure sensor, and is used to inject a fixed amount of water into the expansive soil to simulate rainfall conditions;

[0008] A water source providing device is connected to the water injection device and is used to provide water thereto;

[0009] The control terminal is used to control the water supply device and the water injection volume of the water injection device, monitor the stress data detected by the soil pressure sensor, and calculate and analyze the expansion index.

[0010] In a preferred embodiment, the water injection device includes a flow control device, a telescopic control device, and a telescopic water injection needle assembly, which are sequentially arranged inside the insertion rod from top to bottom. An opening for the telescopic water injection needle assembly to pass through is provided on the wall of the insertion rod.

[0011] A rubber sheet that can be separated from the center is arranged at the opening.

[0012] In a preferred embodiment, the retractable water injection needle assembly includes a fixed ring fixed on the inner wall surface of the insertion rod, and a plurality of water injection needles are retractably provided on the fixed ring. The water outlet ends of the water injection needles can be inserted and exited from corresponding openings, and a wedge is provided at the tail end thereof. The water inlet end of the water injection needle is provided above the tail end thereof. A return spring is also provided on the outside of the water injection needle and is located between the fixed ring and the wedge.

[0013] The soil pressure sensor is an annular pressure sensor.

[0014] In the preferred embodiment, the telescopic control device includes a telescopic push rod and a pushing conical block arranged in sequence from top to bottom inside the insertion rod, the pushing conical block is adapted to the wedge block, a plurality of limit sliders are arranged on the outside of the top end of the pushing conical block, and a limit slide groove corresponding to the limit slider is arranged inside the insertion rod, and the two are slidably connected, and the telescopic push rod is connected to the inner wall of the insertion rod through a plurality of fixed blocks arranged on its outside.

[0015] In the preferred embodiment, the pushing conical block is a retractable structure, specifically including a plurality of hollow conical blocks that can be retracted one by one. The plurality of hollow conical blocks are connected by soft rubber sheets, and a retractable rod is arranged inside the blocks. The two ends of the retractable rod are respectively connected to the inner walls of the top and bottom two hollow conical blocks, and a retractable spring is installed on the outside of the rod.

[0016] In a preferred embodiment, the flow control device includes an electromagnetic flow controller and a water distributor, which are sequentially arranged inside the insertion rod from top to bottom. The water inlet of the electromagnetic flow controller is connected to the water source supply device through a water pipe, and the water outlet is connected to the water inlet of the water distributor. The number of water outlets of the water distributor matches the number of water injection needles and is connected to the water inlet of the corresponding water injection needles through a water distribution hose.

[0017] An opening for the water distribution hose to pass through is provided on the limiting slider.

[0018] In a preferred embodiment, the bottom end of the insertion rod is provided with a piercing cone tip;

[0019] The water source providing device includes a water tank and a water pump. The water inlet end of the water pump is connected to the water tank through a water pipe, and the water outlet end is connected to the water injection device;

[0020] A support plate for placing the control terminal is also provided on the top of the insertion rod, and a through hole is provided at the center of the support plate.

[0021] In a preferred embodiment, the insertion rod is a multi-section telescopic sleeve, which specifically includes a bottom sleeve, multiple intermediate sleeves and a top sleeve that are installed one by one from bottom to top. The soil pressure sensor, the penetration cone tip and the water injection device are all arranged on the bottom sleeve, and the water delivery pipe is a spiral hose.

[0022] The top sleeve and the middle sleeve are provided with a plurality of vertical downward ratchet grooves and telescopic limit grooves, and the top of the middle sleeve and the bottom sleeve are provided with a ratchet structure and a telescopic limit block on the outside. The ratchet structure and the telescopic limit block are matched with the ratchet groove and the telescopic limit groove respectively.

[0023] The outer walls of the top sleeve and the bottom end of the middle sleeve are in an inwardly inclined tapered shape;

[0024] The pawl structure includes a receiving groove opened on the outside of the top of the middle sleeve and the bottom sleeve. The bottom of the receiving groove is rotatably connected to a pawl that is adapted to the pawl groove, and the receiving groove can completely accommodate the pawl. The pawl is rotatably connected to the receiving groove through a rotating shaft set at both ends of its bottom. The outside of the rotating shaft is also provided with a torsion spring for resetting. The two ends of the torsion spring respectively conflict with the opposite surfaces of the pawl and the receiving groove. An electromagnet is embedded in the wall of the receiving groove facing the pawl.

[0025] The method includes:

[0026] S1. Insert the insertion rod into the expansive soil to be tested and ensure that the soil pressure sensor at the bottom of the insertion rod is inserted to the preset depth. Then connect the transmission line of the control terminal and the water supply pipe of the water source device.

[0027] S2. Using the water supply device, a water injection device located above the soil pressure sensor injects a fixed amount of water into the expansive soil, thereby causing the expansive soil around the soil pressure sensor to deform.

[0028] S3. The pressure generated when the expansive soil deforms is monitored by the soil pressure sensor, and the specific stress data is transmitted to the control terminal. The control terminal then calculates and analyzes the expansiveness index to obtain the test results.

[0029] In the preferred solution, the specific calculation and analysis methods are:

[0030] S31. Measurement of soil pressure sensor. The soil pressure sensor records the pressure exerted by the expansive soil on the sensor during the expansion process. The specific formula is:

[0031] ;

[0032] : The pressure exerted by the soil on the sensor, unit: Pa, N / m²;

[0033] F : The force measured by the sensor, unit: N;

[0034] A : The force-bearing area of ​​the sensor, unit: m²;

[0035] S32. Functional analysis of the relationship between water injection volume and expansion. There is a relationship between the expansion of the soil and the amount of water injection. By recording the amount of water injected during the soil expansion process and the soil pressure at the corresponding time point , the pressure change caused by water volume and expansion can be described by establishing a functional relationship:

[0036] ;

[0037] : soil expansion pressure measured by the sensor, unit: Pa, N / m²;

[0038] : water injection volume, unit: m³;

[0039] Generally speaking, the expansion pressure of expansive soil increases as the amount of water injected increases, but this relationship is not linear. The specific relationship can be fitted through experimental data. The specific fitting form is:

[0040] ;

[0041] a 、 b 、 n is the fitting coefficient, determined by experimental data;

[0042] S33. Calculation of the expansion coefficient. The expansion coefficient of soil is an important indicator to measure the expansion capacity of soil when it encounters water. The coefficient is calculated by the relationship between the expansion pressure and the amount of water injection. ke It is an important indicator to measure the expansion capacity of soil when it encounters water. The calculation formula is as follows:

[0043] ;

[0044] : Expansion coefficient, which indicates the rate of change of soil pressure caused by unit water injection, unit: Pa / m³;

[0045] : Change of soil pressure, unit: Pa;

[0046] : Change in water injection volume, unit: m³;

[0047] The expansion coefficient can be obtained by deriving the pressure-injection rate curve of the experimental data;

[0048] If the expansion coefficient is calculated by the fitting form in step S32, the expansion coefficient for:

[0049] ;;;

[0050] This means that as the amount of water injected increases, the expansion coefficient may also change;

[0051] S34. Evaluation of soil physical and mechanical properties. The comprehensive physical and mechanical properties formula is:

[0052] ;

[0053] : Expansion coefficient, unit: Pa / m³;

[0054] : Maximum expansion pressure, unit: Pa;

[0055] : Soil density, unit: N / m³;

[0056] : moisture content, no unit, percentage;

[0057] Through the above steps, the test results are obtained.

[0058] The present invention provides an insertable expansive soil rainfall testing device and method thereof. By arranging a soil pressure sensor at the bottom end of an insertion rod and arranging a water injection device above the sensor, the stress response of expansive soil under rainfall conditions can be effectively simulated, and the expansion performance of the expansive soil layer can be accurately obtained on site. At the same time, it is ensured that water can evenly penetrate into the soil within the sensor detection area, thereby improving the accuracy of stress measurement. At the same time, the control terminal monitors and calculates the water injection volume and soil pressure in real time, which can more accurately analyze the physical and mechanical properties of the expansive soil and provide a reliable reference basis for related engineering and structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present invention will be further described below with reference to the accompanying drawings and examples:

[0060] Figure 1 It is the overall structural diagram of the present invention;

[0061] Figure 2 This is a half-section structural diagram of the insertion rod of the present invention;

[0062] Figure 3 This is a half-section view of the connection structure between the water injection device and the insertion rod of the present invention;

[0063] Figure 4 This invention Figure 3Schematic diagram of the telescopic structure of the middle telescopic control device;

[0064] Figure 5 This is a structural diagram of the connection between the opening and the rubber sheet of the present invention;

[0065] Figure 6 This is a structural diagram of the retractable water injection needle assembly of the present invention;

[0066] Figure 7 It is a structural diagram of the telescopic control device of the present invention;

[0067] Figure 8 This is a front view of a half-section structure of the telescopic control device of the present invention;

[0068] Figure 9 This is a front view of a half-section structure of the telescopic control device of the present invention in the telescopic state;

[0069] Figure 10 This is an exploded view of the connection structure between the top casing and the middle casing of the present invention;

[0070] Figure 11 This is a half-section diagram of the connection structure between the top casing and the middle casing of the present invention;

[0071] Figure 12 This invention Figure 11 A magnified view of the structure in the middle;

[0072] Figure 13 This is a schematic diagram of the torsion spring installation structure of the present invention;

[0073] Figure: control terminal 1; insertion rod 2; opening 201; rubber sheet 202; bottom sleeve 20; multiple intermediate sleeves 21; top sleeve 22; ratchet groove 23; telescopic limit groove 24; telescopic limit block 25; pawl structure 26; receiving groove 260; rotating shaft 261; electromagnet 263; torsion spring 264; soil pressure sensor 3; piercing cone tip 4; water injection device 5; retractable water injection needle assembly 50; fixing ring 501; water injection needle 502; wedge Block 503; return spring 504; telescopic control device 51; pushing conical block 510; hollow conical block 5100; soft rubber sheet 5101; telescopic rod 5102; telescopic spring 5103; limiting slider 5104; opening 5105; telescopic push rod 511; fixed block 5110; flow control device 52; electromagnetic flow controller 520; water distributor 521; water distribution hose 522; water pipe 6; water source supply device 7; support plate 8; DETAILED DESCRIPTION

[0074] Example 1

[0075] like Figure 1-2As shown, an insertable expansive soil rainfall test device includes: an insertion rod 2, an earth pressure sensor 3, a water injection device 5, a water source providing device 7 and a control terminal 1, wherein the insertion rod 2 is used to be inserted into the expansive soil and has a hollow interior. The earth pressure sensor 3 is arranged at the bottom of the insertion rod 2 and can be sent to a test position in the expansive soil through the insertion rod 2 and is used to detect the stress condition of the expansive soil. The water injection device 5 is arranged inside the insertion rod 2 and is used to inject a fixed amount of water into the expansive soil to simulate rainfall conditions. The water injection position is located above the earth pressure sensor 3 and the distance between the two is close, so that the water can be absorbed by the expansive soil around the earth pressure sensor 3 to form an ideal testing environment. The water source providing device 7 is connected to the water injection device 5 and is used to provide it with water. The control terminal 1 is used to control the water injection amount of the water source providing device 7 and the water injection device 5, monitor the stress data detected by the earth pressure sensor 3, and calculate and analyze the expansibility index. The water source providing device 7 and the control terminal 1 are both arranged on the soil surface.

[0076] It should be noted that the control terminal 1 can be a touch screen controller or a controller with a display panel, which is equipped with relevant systems for calculation and control, used for data calculation and equipment control. In addition, the control terminal 1 is connected to the water source supply device 7, the water injection device 5 and the monitoring soil pressure sensor 3 through an electrical connection. In addition, this is a conventional technical means, so it will not be described in detail here.

[0077] In addition, it is equipped with a mobile battery that meets the requirements and is connected to relevant equipment through wires to achieve power supply requirements.

[0078] With this design, a fixed amount of water can be injected into the expansive soil at a preset depth through the water injection device 5, so that the expansive soil produces corresponding expansion deformation, and then the stress data is collected through the soil pressure sensor 3 and transmitted to the control terminal 1, and the control terminal 1 is used to complete the expansion deformation calculation.

[0079] Example 2

[0080] Further illustrate with reference to Example 1, Figure 3-9 The structure shown, in order to be able to inject water into the expansive soil above the soil pressure sensor 3 and avoid unnecessary damage to the water injection needle 502 when the insertion rod 2 is inserted, the water injection device 5 includes a flow control device 52, a telescopic control device 51 and a telescopic water injection needle assembly 50 arranged in sequence inside the insertion rod 2 from top to bottom, and an opening 201 for the telescopic water injection needle assembly 50 to pass through is provided on the wall of the insertion rod 2.

[0081] The retractable water injection needle assembly 50 can retract the water injection needle 502 on the insertion rod 2 into the expansive soil during the process of inserting the insertion rod 2 into the expansive soil to avoid unnecessary damage. At the same time, after being inserted into place, it can be inserted into the expansive soil through the retractable control device 51, so that water can be injected into the interior of the expansive soil to produce a better expansion and deformation effect.

[0082] In the preferred embodiment, a rubber sheet 202 that can be separated from the center is provided at the opening 201, specifically a ring-shaped rubber sheet with a M-shaped splitting line. The M-shaped splitting line divides the circular rubber sheet into multiple sector-shaped areas from the center. When the water injection needle 502 passes through the center, the multiple sector-shaped areas of the ring-shaped rubber sheet will be separated from the M-shaped splitting line. When the water injection needle 502 is retracted, the ring-shaped rubber sheet is restored, thereby further preventing the problem of damage to the water injection needle 502 during the insertion process, and at the same time preventing expansive soil from entering and affecting the equipment.

[0083] In this embodiment, the retractable water injection needle assembly 50 includes a fixing ring 501 fixed on the inner wall surface of the insertion rod 2, and the fixing ring 501 is fixed on the inner wall surface of the insertion rod 2. A plurality of water injection needles 502 are retractably provided on the fixing ring 501. In this embodiment, the number of water injection needles 502 is four, and they are evenly distributed on the fixing ring 501. The four water injection needles 502 can inject water into the expansive soil more evenly. The water outlet end of the water injection needle 502 can pass through the corresponding opening 201, and a wedge block 503 is fixed at its tail end. The water inlet end of the water injection needle 502 is arranged above its tail, and the outside of the water injection needle 502 is also provided with a return spring 504 located between the fixing ring 501 and the wedge block 503.

[0084] With such a design, the four water injection needles 502 can be controlled to extend simultaneously by the resistance wedge 503 , and can be retracted under the action of the return spring 504 after the resistance disappears.

[0085] In addition, the soil pressure sensor 3 is an annular pressure sensor, which can more comprehensively detect the stress changes around it.

[0086] Furthermore, the telescopic control device 51 includes a telescopic push rod 511 and a pushing conical block 510, which are sequentially arranged inside the insertion rod 2 from top to bottom. The pushing conical block 510 is adapted to the wedge block 503. A plurality of limiting sliders 5104 are arranged on the outside of the top of the pushing conical block 510. In this embodiment, there are four limiting sliders 5104, and they are equidistant on the pushing conical block 510. A limiting groove 203 corresponding to the limiting slider 5104 is arranged inside the insertion rod 2. The two are slidably connected to make it easier to lift and lower. The telescopic push rod 511 is connected to the inner wall of the insertion rod 2 through a plurality of fixed blocks 5110 arranged on its outside. In this embodiment, there are four fixed blocks 5110.

[0087] It should be noted that the telescopic push rod 511 can be a cylinder or an electric push rod. In this embodiment, a waterproof electric push rod is preferred.

[0088] With such a design, the telescopic push rod 511 can push the pushing conical block 510 to extend and retract between the wedge blocks 503 of the four water injection needles 502, thereby achieving the effect of controlling the extension and retraction of the four water injection needles 502 through the change of the contact surface.

[0089] In the preferred embodiment, since the distance between the water injection needle 502 and the soil pressure sensor 3 needs to be set relatively close to ensure the test environment of the expansive soil, the length of the pushing conical block 510 is limited. In order to achieve the effect of ejecting the water injection needle 502 in a limited space, the pushing conical block 510 is a retractable structure, specifically including a plurality of hollow conical blocks 5100 that can be retracted one by one. The plurality of hollow conical blocks 5100 are connected to each other by a soft rubber sheet 5101, and a telescopic rod 5102 is arranged inside the telescopic rod 5102. The two ends of the telescopic rod 5102 are respectively connected to the inner walls of the two uppermost and lowermost hollow conical blocks 5100, and a telescopic spring 5103 is installed on the outside.

[0090] With this design, when the pushing conical block 510 moves downward to push the wedge block 503 of the water injection needle 502, the hollow conical block 5100 at the bottom relaxes its resistance due to the space, and the compressible telescopic spring 5103 and the telescopic rod 5102 shrink into the hollow conical block 5100 located above it. By the sequential expansion and contraction of the hollow conical block 5100, the pushing conical block 510 can keep moving downward in the limited space until the water injection needle 502 is completely ejected. Figure 4 As shown, when the pushing conical block 510 moves upward, the pushing conical block 510 can be restored under the action of the telescopic spring 5103.

[0091] It should be noted that the number of hollow conical blocks 5100 and soft rubber sheets 5101 is determined according to the specific length and the ejection length of the water injection needle 502. It should also be noted that when the hollow conical block 5100 below begins to extend and retract, the wedge block 503 and the hollow conical block 5100 above it conflict with each other.

[0092] Furthermore, the flow control device 52 includes an electromagnetic flow controller 520 and a water distributor 521 which are sequentially arranged inside the insertion rod 2 from top to bottom. The water inlet end of the electromagnetic flow controller 520 is connected to the water source providing device 7 through the water pipe 6, and the water outlet end is connected to the water inlet end of the water distributor 521. The number of water outlet ends of the water distributor 521 is adapted to the number of water injection needles 502, and is connected to the water inlet end of the corresponding water injection needles 502 through the water distribution hose 522, thereby realizing the control of the flow rate and ensuring the uniformity of the water output of each water injection needle 502.

[0093] An opening 5105 is provided on the limiting slider 5104 for the water distribution hose 522 to pass through, thereby avoiding unnecessary confusion when the limiting slider 5104 is raised or lowered.

[0094] In a preferred embodiment, a piercing cone tip 4 is fixed to the bottom end of the insertion rod 2 to facilitate its insertion into the expansive soil.

[0095] The water source providing device 7 includes a water tank and a water pump. The water inlet end of the water pump is connected to the water tank through a water pipe, and the water outlet end is connected to the water injection device 5, specifically connected to the water pipe 6, to achieve the effect of water supply.

[0096] A support plate 8 for placing the control terminal 1 is also provided at the top of the insertion rod 2. After the insertion of the insertion rod 2 is completed, the control terminal 1 can be placed on the support plate 8 for operation. At the same time, the setting of the support plate 8 also facilitates the application of pressure on the insertion of the insertion rod 2, and a perforation is provided at the center of the support plate 8, which facilitates the penetration and connection of the transmission line and the water pipe 6.

[0097] It should be noted that the transmission line and the water pipe 6 are both connected through a quick-connect plug-in connector, so that after the insertion rod 2 is inserted, the control terminal 1 and the water source providing device 7 can be quickly connected. The quick-connect plug-in connector can be a commonly used product on the market.

[0098] Example 3

[0099] Further illustrate with reference to Examples 1 and 2, as Figure 2 、 10-13 shows a structure in which, in order to facilitate the carrying of the device, the insertion rod 2 is a multi-section telescopic sleeve, which specifically includes a bottom sleeve 20, a plurality of intermediate sleeves 21 and a top sleeve 22 which are assembled one by one from bottom to top. The specific number of the plurality of intermediate sleeves 21 can be determined according to the actual length. The soil pressure sensor 3, the penetration cone tip 4 and the water injection device 5 are all arranged on the bottom sleeve 20, and the water pipe 6 is a spiral hose for easy extension and retraction.

[0100] In the preferred embodiment, in order to facilitate quick extraction and use, the top sleeve 22 and the middle sleeve 21 are internally provided with a plurality of vertically downward ratchet grooves 23 and telescopic limit grooves 24. In this embodiment, the number of ratchet grooves 23 is four, and the number of telescopic limit grooves 24 is two, and they are evenly distributed. The outside of the top of the middle sleeve 21 and the bottom sleeve 20 is provided with a ratchet structure 26 and a telescopic limit block 25. The ratchet structure 26 and the telescopic limit block 25 respectively cooperate with the ratchet groove 23 and the telescopic limit groove 24. It should be noted that the shape of the ratchet structure 26 and the ratchet groove 23 allows the sleeves to only perform one-way extension movement. In order to facilitate the arrangement of the ratchet structure 26, the ratchet grooves 23 of adjacent sleeves are staggered.

[0101] With this design, all sleeves can be quickly opened by stretching, and the retraction effect can be effectively avoided by the interference relationship between the pawl structure 26 and the ratchet groove 23, and the telescopic limit groove 24 and the telescopic limit block 25 can avoid separation.

[0102] In addition, the outer walls of the bottom ends of the top casing 22 and the middle casing 21 are in an inwardly inclined tapered shape, so as to facilitate better insertion into the expansive soil.

[0103] Furthermore, the pawl structure 26 includes a receiving groove 260 opened on the outside of the top of the middle sleeve 21 and the bottom sleeve 20. The bottom of the receiving groove 260 is rotatably connected with a pawl 262 adapted to the ratchet groove 23, and the receiving groove 260 can completely accommodate the pawl 262. The pawl 262 is rotatably connected to the receiving groove 260 through a rotating shaft 261 set at both ends of its bottom. The outside of the rotating shaft 261 is also provided with a torsion spring 264 for resetting. The two ends of the torsion spring 264 respectively conflict with the opposite surfaces of the pawl 262 and the receiving groove 260. Therefore, through the shape setting of the pawl structure 26 and the ratchet groove 23, when the pawl structure 26 moves downward, the pawl 262 can be continuously retracted into the receiving groove 260 through contact with the ratchet groove 23. When the pawl structure 26 wants to move upward, it will conflict with the ratchet groove 23 to achieve a locking effect, so that the insertion rod 2 can maintain its length and be inserted into the expansive soil.

[0104] In addition, in order to facilitate the retraction and carrying of the insertion rod 2 when not in use, an electromagnet 263 is embedded in the wall of the accommodating groove 260 facing the pawl 262. The specific retraction method is: appropriately stretch the sleeve downward to properly disengage the pawl 262 from the ratchet groove 23, then turn on the electromagnet 263 to absorb the pawl 262 into the accommodating groove 260, and then retract it.

[0105] It should be noted that the electromagnet 263 is connected to the control terminal 1 through a transmission line.

[0106] Example 4

[0107] Further illustrate with reference to Examples 1-3, Figure 1 The structure shown in FIG. 1 includes a method for using the above-mentioned insertion-type expansive soil rainfall testing device, the method comprising:

[0108] S1. Insert the insertion rod 2 into the expansive soil to be tested, and ensure that the soil pressure sensor 3 at the bottom of the insertion rod 2 is inserted to the preset depth, and then connect the transmission line of the control terminal 1 and the water supply pipe of the water source providing device 7;

[0109] S2. The water supply device 7 supplies water to the water injection device 5 located above the soil pressure sensor 3 to inject a certain amount of water into the expansive soil, thereby causing the expansive soil around the soil pressure sensor 3 to deform.

[0110] S3. The soil pressure sensor 3 monitors the pressure generated when the expansive soil is deformed, and transmits the specific stress data to the control terminal 1. The control terminal 1 calculates and analyzes the expansiveness index to obtain the test results.

[0111] In the preferred solution, the specific calculation and analysis methods are:

[0112] S31, measurement of soil pressure sensor 3. Soil pressure sensor 3 records the pressure exerted by the expansive soil on the sensor during the expansion process. The specific formula is:

[0113] ;

[0114] : The pressure exerted by the soil on the sensor, unit: Pa, N / m²;

[0115] F : The force measured by the sensor, unit: N;

[0116] A : The force-bearing area of ​​the sensor, unit: m²;

[0117] S32. Functional analysis of the relationship between water injection volume and expansion. There is a relationship between the expansion of the soil and the amount of water injection. By recording the amount of water injected during the soil expansion process and the soil pressure at the corresponding time point , the pressure change caused by water volume and expansion can be described by establishing a functional relationship:

[0118] ;

[0119] : soil expansion pressure measured by the sensor, unit: Pa, N / m²;

[0120] : water injection volume, unit: m³;

[0121] Generally speaking, the expansion pressure of expansive soil increases as the amount of water injected increases, but this relationship is not linear. The specific relationship can be fitted through experimental data. The specific fitting form is:

[0122] ;

[0123] a 、 b 、 n is the fitting coefficient, determined by experimental data;

[0124] S33. Calculation of the expansion coefficient. The expansion coefficient of soil is an important indicator to measure the expansion capacity of soil when it encounters water. The coefficient is calculated by the relationship between the expansion pressure and the amount of water injection. ke It is an important indicator to measure the expansion capacity of soil when it encounters water. The calculation formula is as follows:

[0125] ;

[0126] : Expansion coefficient, which indicates the rate of change of soil pressure caused by unit water injection, unit: Pa / m³;

[0127] : Change of soil pressure, unit: Pa;

[0128] : Change in water injection volume, unit: m³;

[0129] The expansion coefficient can be obtained by deriving the pressure-injection rate curve of the experimental data;

[0130] If the expansion coefficient is calculated by the fitting form in step S32, the expansion coefficient for:

[0131] ;;;

[0132] This means that as the amount of water injected increases, the expansion coefficient may also change;

[0133] S34. Evaluation of soil physical and mechanical properties. The comprehensive physical and mechanical properties formula is:

[0134] ;

[0135] : Expansion coefficient, unit: Pa / m³;

[0136] : Maximum expansion pressure, unit: Pa;

[0137] : Soil density, unit: N / m³;

[0138] : moisture content, no unit, percentage;

[0139] Through the above steps, the test results are obtained.

[0140] The above embodiments are merely preferred technical solutions of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention shall be the technical solutions set forth in the claims, including equivalent alternatives to the technical features of the technical solutions set forth in the claims. In other words, equivalent alternatives and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. An insertable expansive soil rainfall testing device, characterized in that: include: An insertion rod (2) for inserting into expansive soil; A soil pressure sensor (3) is provided at the bottom of the insertion rod (2) and is used to detect the stress of the expansive soil; A water injection device (5) is arranged inside the insertion rod (2), and the water injection position is located above the soil pressure sensor (3), and is used to inject a fixed amount of water into the expansive soil to simulate rainfall conditions; A water source providing device (7), connected to the water injection device (5), for providing water thereto; A control terminal (1) is used to control the water injection amount of the water source supply device (7) and the water injection device (5), monitor the stress data detected by the soil pressure sensor (3), and calculate and analyze the expansion index; The water injection device (5) comprises a flow control device (52), a telescopic control device (51) and a telescopic water injection needle assembly (50) which are sequentially arranged inside the insertion rod (2) from top to bottom. An opening (201) for the telescopic water injection needle assembly (50) to pass through is provided on the wall surface of the insertion rod (2); A rubber sheet (202) that can be separated from the center is provided at the opening (201); The retractable water injection needle assembly (50) comprises a fixed ring (501) fixed on the inner wall surface of the insertion rod (2), a plurality of water injection needles (502) are retractably provided on the fixed ring (501), the water outlet ends of the water injection needles (502) can be passed through the corresponding openings (201), and a wedge block (503) is provided at the tail end thereof, the water inlet end of the water injection needle (502) is arranged above the tail end thereof, and a return spring (504) is also provided on the outside of the water injection needle (502) and is located between the fixed ring (501) and the wedge block (503); The soil pressure sensor (3) is an annular pressure sensor; The telescopic control device (51) includes a telescopic push rod (511) and a pushing cone block (510) which are sequentially arranged inside the insertion rod (2) from top to bottom. The pushing cone block (510) is adapted to the wedge block (503). A plurality of limiting sliders (5104) are arranged on the outside of the top of the pushing cone block (510). A limiting slide groove (203) corresponding to the limiting sliders (5104) is arranged inside the insertion rod (2). The two are slidably connected. The telescopic push rod (511) is connected to the inner wall of the insertion rod (2) through a plurality of fixing blocks (5110) arranged on the outside of the telescopic push rod (511). The pushing conical block (510) is a telescopic structure, specifically comprising a plurality of hollow conical blocks (5100) that can be retracted one by one. The plurality of hollow conical blocks (5100) are connected by soft rubber sheets (5101), and a telescopic rod (5102) is provided inside the hollow conical blocks. The two ends of the telescopic rod (5102) are respectively connected to the inner walls of the uppermost and lowermost hollow conical blocks (5100), and a telescopic spring (5103) is provided on the outside of the telescopic rod.

2. The insertable expansive soil rainfall testing device according to claim 1, characterized in that: The flow control device (52) comprises an electromagnetic flow controller (520) and a water distributor (521) which are sequentially arranged inside the insertion rod (2) from top to bottom. The water inlet end of the electromagnetic flow controller (520) is connected to the water source providing device (7) through the water pipe (6), and the water outlet end is connected to the water inlet end of the water distributor (521). The number of water outlet ends of the water distributor (521) matches the number of water injection needles (502), and is connected to the water inlet ends of the corresponding water injection needles (502) through the water distribution hose (522). The limiting slider (5104) is provided with an opening (5105) for the water distribution hose (522) to pass through.

3. The insertable expansive soil rainfall testing device according to claim 1 or 2, characterized in that: The bottom end of the insertion rod (2) is provided with a piercing cone tip (4); The water source providing device (7) includes a water tank and a water pump, wherein the water inlet of the water pump is connected to the water tank via a water pipe, and the water outlet is connected to the water injection device (5); A support plate (8) for placing the control terminal (1) is also provided on the top of the insertion rod (2), and a through hole is provided at the center of the support plate (8).

4. The insertable expansive soil rainfall testing device according to claim 3, characterized in that: The insertion rod (2) is a multi-section telescopic sleeve, which specifically includes a bottom sleeve (20), a plurality of intermediate sleeves (21) and a top sleeve (22) which are mounted one by one from bottom to top. The soil pressure sensor (3), the piercing cone tip (4) and the water injection device (5) are all arranged on the bottom sleeve (20), and the water delivery pipe (6) is a spiral hose. A plurality of vertically downward ratchet grooves (23) and telescopic limit grooves (24) are provided inside the top sleeve (22) and the middle sleeve (21), and a ratchet structure (26) and a telescopic limit block (25) are provided outside the top end of the middle sleeve (21) and the bottom sleeve (20), and the ratchet structure (26) and the telescopic limit block (25) are matched with the ratchet grooves (23) and the telescopic limit grooves (24) respectively. The outer walls of the bottom ends of the top sleeve (22) and the middle sleeve (21) are in an inwardly inclined conical shape; The ratchet structure (26) includes a receiving groove (260) provided on the outside of the top of the middle sleeve (21) and the bottom sleeve (20), the bottom of the receiving groove (260) is rotatably connected to a ratchet (262) adapted to the ratchet groove (23), and the receiving groove (260) can completely accommodate the ratchet (262), the ratchet (262) is rotatably connected to the receiving groove (260) via a rotating shaft (261) provided at both ends of the bottom thereof, and a torsion spring (264) for resetting is also provided on the outside of the rotating shaft (261), the two ends of the torsion spring (264) respectively contact the opposite surfaces of the ratchet (262) and the receiving groove (260), and an electromagnet (263) is embedded in the wall of the receiving groove (260) facing the ratchet (262).

5. A method for using the insertable expansive soil rainfall testing device according to any one of claims 1 to 4, characterized in that: The method includes: S1. Insert the insertion rod (2) into the expansive soil to be tested, and ensure that the soil pressure sensor (3) at the bottom end of the insertion rod (2) is inserted to a preset depth, and then connect the transmission line of the control terminal (1) and the water supply pipe of the water source supply device (7); S2, supplying water through the water source providing device (7), so that the water injection device (5) located above the soil pressure sensor (3) injects a fixed amount of water into the expansive soil, thereby causing the expansive soil around the soil pressure sensor (3) to deform; S3, monitoring the pressure generated when the expansive soil is deformed by the soil pressure sensor (3), transmitting the specific stress data to the control terminal (1), and calculating and analyzing the expansiveness index by the control terminal (1) to obtain the test results.

6. A method for using the insertable expansive soil rainfall testing device according to claim 5, characterized in that: The specific calculation and analysis methods are as follows: S31, measurement of soil pressure sensor (3), soil pressure sensor (3) records the pressure exerted by the expansive soil on the sensor during the expansion process. The specific formula is: ； : soil expansion pressure measured by the sensor, unit: Pa, N / m²; F : The force measured by the sensor, unit: N; A : The force-bearing area of ​​the sensor, unit: m²; S32. Functional analysis of the relationship between water injection volume and expansion. There is a relationship between the expansion of the soil and the amount of water injection. By recording the amount of water injected during the soil expansion process and the soil expansion pressure measured by the sensor at the corresponding time point , by establishing a functional relationship to describe the pressure change caused by water volume and expansion: ； : soil expansion pressure measured by the sensor, unit: Pa, N / m²; : water injection volume, unit: m³; Among them, the expansion pressure of expansive soil increases as the water injection volume increases, but this relationship is not linear. The specific relationship form is fitted by experimental data, and the specific fitting form is: ； 、 b 、 n is the fitting coefficient, determined by experimental data; S33. Calculation of expansion coefficient, soil expansion coefficient It is an important indicator to measure the expansion capacity of soil when it encounters water. The coefficient is calculated by the relationship between the expansion pressure and the amount of water injected. The calculation formula is as follows: ； : Expansion coefficient, which indicates the rate of change of soil expansion pressure caused by unit water injection, unit: Pa / m³; : soil expansion pressure change measured by the sensor, unit: Pa; : Change in water injection volume, unit: m³; The expansion coefficient is obtained by deriving the pressure-water injection curve of the experimental data; S34. Evaluation of soil physical and mechanical properties. The comprehensive physical and mechanical properties formula is: ； : Expansion coefficient, unit: Pa / m³; : Maximum expansion pressure, unit: Pa; : Soil density, unit: N / m³; : moisture content, no unit, percentage; Through the above steps, the test results are obtained.

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