Method and device for testing porosity of soil body

Abstract

The invention discloses a soil porosity testing method and device, and the soil porosity testing method comprises the following steps: preparing a salt solution with a first mass concentration c1, pouring the salt solution into a saturation cylinder, putting a saturator into the saturation cylinder, and reading the volume reading V0 of the side wall of the saturation cylinder; filling the soil body sample into a saturator, then putting the soil body sample into the saturation cylinder again, ensuring that the saturation cylinder forms a closed environment, starting a vacuum pump to enable the interior of the saturation cylinder to be in a negative pressure state, reading the volume reading V1 of the side wall of the saturation cylinder after vacuumizing for the first time, and calculating the volume Va of air in pores of the soil body sample according to a formula Va = V1-V0; taking out the soil body sample from the saturator, independently putting the soil body sample into a saturation cylinder, and decomposing the soil body sample into the salt solution; taking out the salt solution, measuring the mass concentration of the salt solution as c2, and calculating the volume Vw occupied by pore water in the soil body sample according to the change of the mass concentration of the salt solution; and calculating the porosity of the soil body sample according to the formula # imgabs0 #, wherein Vv is the total volume of the soil body sample. According to the invention, the pore water volume is considered, so that the test accuracy is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of soil detection technology, and in particular to a soil porosity testing method and device. Background Art

[0002] Soil porosity is one of the important parameters to measure soil structural characteristics and engineering properties. Soil porosity not only affects the permeability, compressibility, shear strength and other properties of the soil, but also determines engineering problems such as foundation settlement, slope instability, and groundwater inrush. Therefore, studying the test method of soil porosity is of great significance for ensuring engineering safety, improving engineering quality, and reducing engineering risks. At present, the common soil porosity test methods include volume replacement method, pycnometer method, mercury injection method, gas expansion method, image processing method, mercury intrusion method, etc.

[0003] Among them, the method of calculating soil porosity through volume replacement usually only replaces the air in the soil pores and regards it as the total pore volume. The calculation result ignores the proportion of pore water and is often too small. If the drying step in the rock and concrete porosity test is used before the pores of the soil sample are replaced by other media, the error caused by ignoring pore water can be solved in theory. However, for the soil, forced drying of free water and bound water between soil particles will cause certain disturbances to the arrangement of soil particles and pore structure, especially for loose gravel soil, causing the porosity of the soil to change during the drying process, making the final test results deviate further from the accurate value.

[0004] In addition, the image processing method has high equipment and testing fees. The mercury intrusion method requires pressure, which will cause the soft soil to be crushed by pressure and is only suitable for pore size analysis of harder solids. In addition, mercury and instruments are expensive, so the test cost is high when using this method. At the same time, mercury is a toxic chemical, and improper use will cause harm to experimenters and the environment.

[0005] In summary, the soil porosity test method still needs to be improved to solve the problems of the existing test method ignoring the error caused by the volume occupied by soil pore water, as well as the high cost and use risks of the existing test methods. Summary of the invention

[0006] The present application aims to solve at least one of the above technical problems in the prior art to a certain extent. To this end, the first embodiment of the present application provides a soil porosity testing method that can calculate the volume occupied by soil pore water, thereby improving the measurement accuracy of soil porosity.

[0007] The soil porosity testing method according to the first embodiment of the present application includes the following steps:

[0008] Step 1: Prepare a salt solution with a first mass concentration of c1 and pour it into a saturation cylinder. Place the saturator into the saturation cylinder and read the volume reading on the side wall of the saturation cylinder as V0;

[0009] Step 2: After the soil sample is filled in the saturator, it is placed in the saturation cylinder again to ensure that the saturation cylinder forms a closed environment. Turn on the vacuum pump to make the saturation cylinder in a negative pressure state. After vacuuming and saturation, read the volume reading of the side wall of the saturation cylinder as V1, and calculate the volume V occupied by the air in the pores of the soil sample. a =V1-V0;

[0010] Step 3: Take the soil sample out of the saturator and place it in a saturation tank separately to decompose the soil sample in the salt solution;

[0011] Step 4: Take out the salt solution and measure its mass concentration as c2. Calculate the volume of pore water in the soil sample as V according to the change of mass concentration of the salt solution. w ;

[0012] Step 5: Calculate the porosity of the soil sample Where V v is the total volume of the soil sample.

[0013] Based on the above technical scheme, the first embodiment of the present application has at least the following beneficial effects: the soil porosity testing method provided by the present application utilizes a vacuum pump to place the saturation cylinder in a negative pressure state, thereby causing the air in the pores of the soil sample placed in the saturator to be replaced by a salt solution, and the volume of the air in the pores of the soil sample is measured by reading the volume change of the salt solution in the saturation cylinder; the saturated soil sample is placed in a salt solution for decomposition, and during the decomposition of the soil in the salt solution, the pore water in the soil sample fully infiltrates into the salt solution, causing the mass concentration of the salt solution to change, and the volume occupied by the pore water in the soil sample is calculated by the change in the mass concentration of the salt solution; finally, the volume occupied by the air and water in the pores of the soil sample is divided by the total volume of the soil sample to obtain a more accurate soil porosity. The present application uses a salt solution as a volume replacement medium, which is low in cost and risk-free, and at the same time, the pore water volume is taken into account for soil porosity determination, and the test accuracy is greatly improved.

[0014] According to the soil porosity testing method of the first embodiment of the present application, the volume V occupied by the pore water in the soil sample in step 4 is w The calculation formula is

[0015] In the formula, ρ w is the density of the original pore water in the soil sample.

[0016] According to the soil porosity testing method of the first aspect of the present application, the process of decomposing the soil sample in the salt solution in step 3 is specifically any of the following methods or combinations:

[0017] The soil sample is stirred by the rotation of the stirring blades in the saturation cylinder;

[0018] The decomposition of the soil sample is accelerated by shaking the saturated cylinder.

[0019] According to the soil porosity testing method of the first aspect of the present application, in step 4, the soil sample needs to be separated from the salt solution before taking out the salt solution. The process of separating the soil sample from the salt solution is specifically as follows: starting the centrifugal device arranged at the bottom of the saturation cylinder, the centrifugal device drives the saturation cylinder to rotate centrifugally, and the soil sample is separated from the salt solution by setting the rotation speed and centrifugal time.

[0020] According to the soil porosity testing method of the first aspect of the present application, after taking out the salt solution in step 4, the salt solution is further filtered and its mass concentration is measured as c2.

[0021] According to the soil porosity testing method of the first embodiment of the present application, the salt solution is a sodium chloride solution.

[0022] A soil porosity testing device according to an embodiment of the second aspect of the present application includes: a saturator for accommodating a soil sample;

[0023] A saturation cylinder is provided with a stirring blade and a sealing cover, wherein the sealing cover is used to seal the saturation cylinder into a closed environment;

[0024] A vacuum pump, the vacuum pump is tightly connected to the sealing cover through an exhaust pipe, and is used to make the saturated cylinder in a negative pressure state by vacuuming;

[0025] A centrifugal device is connected to the base of the saturation cylinder through a transmission device, and is used to drive the saturation cylinder to perform centrifugal rotation.

[0026] According to the soil porosity testing device of the second embodiment of the present application, the saturation cylinder is made of a transparent material and has scale lines on its side walls.

[0027] According to the soil porosity testing device of the second aspect of the present application, the soil porosity testing device also includes an oscillating table, and the bottom of the saturation cylinder is fixedly connected to the top surface of the oscillating table through a support frame.

[0028] According to the soil porosity testing device of the second embodiment of the present application, the side wall of the saturation cylinder is provided with a liquid outlet, and the liquid outlet is equipped with a water stop clamp.

[0029] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a schematic diagram of the structure of a soil porosity testing device in an embodiment of the second aspect of the present application;

[0032] Figure 2 This is a schematic diagram of the structure of a saturator in an embodiment of the second aspect of the present application;

[0033] Reference numerals:

[0034] Saturator 100, steel ring base 110, knob 120, hoop 130, fixed side rod 140, three-valve membrane 150, permeable stone 160, saturation cylinder 200, sealing cover 210, stirring blade 220, liquid outlet 230, water stop clamp 231, vacuum pump 300, exhaust pipe 310, centrifugal device 400, centrifugal rotor 410, transmission device 420, oscillating shaker 500, supporting steel frame 510, beaker 600, Baume meter 610. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0037] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0038] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0039] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0040] The technical solution of the present application will be further described below in conjunction with embodiments and drawings.

[0041] The present application provides a soil porosity testing method, which can calculate the volume occupied by soil pore water, thereby improving the measurement accuracy of soil porosity. The soil porosity testing method includes the following steps:

[0042] Step 1: Prepare a salt solution with a first mass concentration of c1 and pour it into a saturation cylinder. Place the saturator into the saturation cylinder and read the volume reading on the side wall of the saturation cylinder as V0;

[0043] Step 2: After the soil sample is filled in the saturator, it is placed in the saturation cylinder again to ensure that the saturation cylinder forms a closed environment. Turn on the vacuum pump to make the saturation cylinder in a negative pressure state. After the vacuum is drawn for the first time, read the volume reading of the side wall of the saturation cylinder as V1, and calculate the volume V occupied by the air in the pores of the soil sample. a =V1-V0;

[0044] Step 3: Take the soil sample out of the saturator and place it in a saturation tank separately to decompose the soil sample in the salt solution;

[0045] Step 4: Take out the salt solution and measure its mass concentration as c2. Calculate the volume of pore water in the soil sample as V according to the change of mass concentration of the salt solution. w ;

[0046] Step 5: Calculate the porosity of the soil sample Where V v is the total volume of the soil sample.

[0047] As an example, the salt solution in this application is a sodium chloride solution, which has a relatively stable chemical property. At the same time, the sodium chloride solution is a non-toxic and harmless reagent that is easily obtained, has a low cost of use, and a simple method, which is conducive to the promotion of the method. It should be noted that the salt solution in this application can also be selected from other solutions with relatively stable chemical properties that are not easy to react with soil samples, such as sodium sulfate solution.

[0048] It should be noted that after the soil sample is loaded into the saturator, it is placed in the saturation cylinder again to ensure that the saturation cylinder forms a closed environment, and the vacuum pump is turned on to make the saturation cylinder in a negative pressure state. During the vacuuming process, the air in the soil sample is replaced by the salt solution, resulting in a decrease in the volume of the salt solution in the saturation cylinder and a decrease in the reading of the scale line on the side wall of the saturation cylinder. The volume of the decreased reading is the volume of the air in the soil sample, that is, the volume reading of the side wall of the saturation cylinder after the first vacuuming is V1, and the volume occupied by the air in the pores of the soil sample is V a = V1 - V0. It can be understood that the present application uses salt solution as a medium for replacing the air volume in the soil sample, which is low in cost and risk-free.

[0049] Optionally, the first time of vacuuming in this application is set to 24 hours to ensure that the air in the pores of the soil sample has been completely replaced by the sodium chloride solution to reach a saturated state, thereby improving the measurement accuracy of the porosity of the soil sample. It should be noted that other longer or shorter time spans can also be selected for the first time, and adjustments can be made according to the specific conditions of the soil sample to be tested.

[0050] It should be noted that steps 1 and 2 of the present application only calculate the volume occupied by the air in the pores of the soil sample, and steps 3 to 5 of the present application further take into account the volume occupied by the pore water in the soil sample, thereby greatly improving the test accuracy of the soil porosity.

[0051] As an example, in step 3, the soil sample is taken out from the saturator and placed separately in a saturation cylinder to decompose the soil sample in the salt solution. It should be noted that in the process of decomposing the soil sample in the salt solution, the free water between the soil particles and most of the weakly bound water will be separated from the soil particles and dissolved in the salt solution. The infiltration of water in the soil sample will cause the change of the mass concentration of the original salt solution. The present application calculates the volume occupied by pore water in the soil sample by the change of the mass concentration of the salt solution.

[0052] As an example, in step 4, the salt solution is taken out and its mass concentration is measured as c2. The volume of pore water in the soil sample is calculated as V according to the change of the mass concentration of the salt solution. wSpecifically, the volume V occupied by the pore water in the soil sample in step 4 is w The calculation formula is In the formula, ρ w is the density of the original pore water in the soil sample. w Usually 1g / cm 3 , which can be adjusted according to the specific conditions of the soil sample to be tested.

[0053] Furthermore, in step 3 of the present application, any of the following methods or combinations are used to ensure that the soil sample is fully decomposed in the salt solution: (1) The soil sample is stirred by rotating the stirring blades in the saturation cylinder; (2) The decomposition of the soil sample is accelerated by oscillating and shaking the saturation cylinder. The soil sample is cut into a cylindrical shape before being loaded into the saturator. The rotation of the stirring blades in the saturation cylinder can cut and stir the soil sample, thereby accelerating the decomposition of the soil sample. Similarly, oscillating and shaking the saturation cylinder can drive the salt solution and the soil sample in the cylinder to collide with each other, thereby accelerating the decomposition of the soil sample and allowing the pore water in the soil sample to fully penetrate into the salt solution. It should be noted that other methods can also be used to accelerate the decomposition of the soil sample in the salt solution, such as manual rapid stirring or centrifugal rotation of the saturation cylinder, etc., and the present application does not give examples one by one here.

[0054] As an example, in step 4 of the present application, the soil sample needs to be separated from the salt solution before taking out the salt solution, and the taken out salt solution is the supernatant after the soil sample and the salt solution are separated. Specifically, the process of separating the soil sample from the salt solution can be: starting a centrifugal device arranged at the bottom of the saturation cylinder, the centrifugal device drives the saturation cylinder to rotate centrifugally, and the soil sample and the salt solution are separated by setting the rotation speed and centrifugal time.

[0055] It is understandable that the principle of the centrifugal device is to generate a relatively strong centrifugal force through high-speed rotation, accelerate the sedimentation rate of different specific gravity components (solid particles and liquid) in the solution, and thus achieve solid-liquid separation. In the present application, the centrifugal device drives the saturated cylinder to rotate at high speed, accelerates the sedimentation of soil particles in the salt solution, and finally achieves the separation of the soil sample and the salt solution, and finally the salt solution is located above the soil sample to form a supernatant. It should be noted that other methods can also be used in the present application to separate the soil sample from the salt solution, such as standing and filtering, etc., and this application does not give examples one by one here.

[0056] Optionally, in step 4 of the present application, after taking out the salt solution, the salt solution is further filtered and its mass concentration is measured as c2. It can be understood that the filtration operation can further remove the soil particles mixed in the salt solution, ensuring that the measurement result of the mass concentration of the salt solution is more accurate.

[0057] It can be understood that the volume of air in the pores of the soil sample V in this application is aand the volume of pore water in the soil sample V w To calculate the soil porosity, the calculation formula for the soil sample porosity P is: Where V v is the total volume of the soil sample. Furthermore, the volume of air in the pores of the soil sample V a =V1-V0, the volume occupied by pore water in the soil sample

[0058] In summary, the calculation formula of the porosity P of soil samples can be expanded to

[0059] Where: V w is the pore water volume, V a is the volume of air in the pores, V v is the total volume of the soil sample; V1 is the total volume of the salt solution and the sample after the soil sample is saturated in the saturation cylinder for 24 hours, V0 is the volume reading of the solution when the saturator is placed in the saturation cylinder, c2 is the mass concentration of the solution after the soil sample is stirred and dissolved in the saturation cylinder, c1 is the initial mass concentration of the salt solution, ρ w The density of the original pore water in the soil, usually 1g / cm 3 .

[0060] It can be understood that in the present application, the volume of air in the pores of the soil sample is first calculated by the test principle of volume displacement, and then the volume of pore water in the soil sample is calculated by the change in the mass concentration of the soaking salt solution before and after the soil sample is stirred and decomposed, which largely avoids the influence on the original pores of the soil before saturation, and at the same time compensates for the error of pore water on the test results, so that the accuracy of the soil porosity test results is greatly improved.

[0061] The second embodiment of the present application also provides a soil porosity testing device, which can realize integrated operations such as saturation, decomposition, and centrifugation of soil samples during the test, thereby avoiding the impact of splashing liquid when changing containers on the test results.

[0062] refer to Figure 1The soil porosity testing device provided in the present application includes: a saturator 100, a saturation cylinder 200, a vacuum pump 300 and a centrifugal device 400, wherein the saturator 100 is used to accommodate a soil sample; the saturation cylinder 200 is provided with a stirring blade 220 and a sealing cover 210, wherein the stirring blade 220 is used to accelerate the decomposition of the soil sample in the salt solution, and the sealing cover 210 is used to seal the saturation cylinder 200 into a closed environment; the vacuum pump 300 is tightly connected to the sealing cover 210 through an exhaust pipe 310, and is used to make the saturation cylinder 200 in a negative pressure state by vacuuming; the centrifugal device 400 is connected to the base of the saturation cylinder 200 through a transmission device 420, and is used to drive the saturation cylinder 200 to rotate centrifugally.

[0063] As an example, in the present application, the saturation cylinder 200 is made of a transparent material and has scale lines on the side wall, which is convenient for checking the change in the volume of the salt solution in the saturation cylinder 200. The volume of the air in the pores of the soil sample can be calculated by the change in the scale line reading. The specific process is:

[0064] (1) Prepare a salt solution with a known mass concentration of c1 and pour it into the saturation cylinder 200. Place the saturator 100 into the saturation cylinder 200 and record the volume of the solution as V0 according to the scale on the side wall of the saturation cylinder 200. (2) Take out the saturator 100, load the soil sample to be tested into the saturator 100 and put them back into the saturation cylinder 200. (3) Connect the exhaust pipe 310 and the sealing cover 210 tightly, and then connect the sealing cover 210 and the saturation cylinder 200 tightly. The saturation cylinder 200 forms a closed environment through the sealing cover 210. Then, turn on the vacuum pump 300 to keep the inside of the saturation cylinder 200 in a negative pressure environment. After 24 hours of vacuuming, the soil sample is considered to be saturated. At this time, observe the reading on the side wall of the saturation cylinder 200 and record it as volume V1. At this time, the difference between V1 and V0 is the volume V occupied by the air in the pores of the soil sample. a , V a =V1-V0.

[0065] refer to Figure 2 In the present application, the saturator 100 includes a steel ring base 110, a knob 120, a fixed side rod 140, a three-valve membrane 150, a hoop 130 and a permeable stone 160, wherein the interior of the saturator 100 is cylindrical, and the upper and lower steel ring bases 110 are fastened together by the matching connection of the knob 120 and the fixed side rod 140. As an example, the process of filling the soil sample in the saturator 100 is as follows: the soil sample to be tested is cut into a cylinder and then filled into the saturator 100, and then fixed by the knob 120. Optionally, the saturator 100 is made of stainless steel.

[0066] The soil porosity testing device provided in the present application accelerates the decomposition of the saturated soil sample in the salt solution by setting a stirring blade 220 in the saturation cylinder 200, and accelerates the separation of the soil sample from the salt solution by setting a centrifugal device 400 to measure the change in the mass concentration of the salt solution, thereby calculating the volume of pore water in the soil sample. The specific process is as follows:

[0067] (4) After taking out the soil sample from the saturator 100, place it separately into the saturation cylinder 200. Due to the effect of gravity, the soil sample will sink to the bottom of the saturation cylinder 200; (5) Start the stirring blade 220 at the bottom of the saturation cylinder 200, set the stirring blade 220 to work at a certain speed for a period of time until the soil sample is completely decomposed in the salt solution, and then stop stirring; (6) Unplug the exhaust pipe 310 connected to the sealing cover 210, start the centrifugal device 400 at the bottom of the saturation cylinder 200, set the speed and centrifugal time to completely separate the soil particles of the soil sample from the salt solution, and then close the centrifugal device 400.

[0068] Optionally, the centrifugal device 400 includes a centrifugal rotor 410, a transmission device 420 and a stirring centrifugal control system. The transmission device 420 is fixedly connected to the bottom of the saturation cylinder 200, and is used to transmit the torque of the centrifugal rotor 410 to the saturation cylinder 200, driving the saturation cylinder 200 to rotate at high speed. The stirring centrifugal control system can control the rotation time and speed of the stirring blade 220 and the centrifugal rotor 410 respectively.

[0069] In summary, the soil porosity testing device provided in the present application can realize integrated operations such as saturation, decomposition, and centrifugation of soil samples. There is no need to transfer salt solution during the test process, which makes the operation more convenient and avoids errors in the test results caused by taking samples at different stages. At the same time, it also avoids the impact of splashing liquid on the test results when changing containers.

[0070] As an example, the soil porosity testing device provided in the present application further includes an oscillating table 500, and the bottom of the saturated cylinder 200 is fixedly connected to the top surface of the oscillating table 500 through a supporting steel frame 510 to prevent the saturated cylinder 200 from shifting or falling during the oscillation process. In the process of decomposing the soil sample in the salt solution, the oscillating table 500 at the bottom of the supporting steel frame 510 of the saturated cylinder 200 is started, so that the oscillating table 500 oscillates the mixed solution in the saturated cylinder 200 at a certain frequency and amplitude, so that the soil sample is more fully decomposed in the salt solution.

[0071] As an example, the side wall of the saturation cylinder 200 is provided with a liquid outlet 230, and the liquid outlet 230 is equipped with a water stop clamp 231. Figure 1By setting a liquid outlet 230 on the side wall of the saturation cylinder 200, it is convenient to take out the supernatant after the soil sample and the salt solution are separated. The water stop clamp 231 of the liquid outlet 230 can be opened to allow the supernatant after centrifugation to flow out, which is convenient for measuring the mass concentration of the salt solution. Optionally, by fixing a filter membrane on the section of the liquid outlet 230, the salt solution can be further filtered to improve the measurement accuracy of the mass concentration change of the salt solution.

[0072] It can be understood that the soil porosity testing device provided in the present application also includes a beaker 600 and a Baume meter 610. The supernatant flowing out of the liquid outlet 230 is collected in the beaker 600. The mass concentration of the salt solution at this time is read by the Baume meter 610 as c2. The calculation formula of the porosity P of the soil sample is:

[0073] Where: V w is the pore water volume, V a is the volume of air in the pores, V v is the total volume of the soil sample; V1 is the total volume of the salt solution and the sample after the soil sample is saturated in the saturation cylinder 200 for 24 hours, V0 is the volume reading of the solution when the saturator 100 is placed in the saturation cylinder 200, c2 is the mass concentration of the solution after the soil sample is stirred and dissolved in the saturation cylinder 200, c1 is the initial mass concentration of the salt solution, ρ w The density of the original pore water in the soil, usually 1g / cm 3 .

[0074] It should be noted that when a liquid outlet 230 is provided on the side wall of the saturated cylinder 200 , in the vacuuming step of the aforementioned step, in addition to sealing the saturated cylinder 200 by means of the sealing cover 210 , the liquid outlet 230 also needs to be closed by means of the water stop clamp 231 to ensure that a closed environment is formed in the saturated cylinder 200 .

[0075] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. A soil porosity testing method, characterized in that: The steps include: Step 1: Prepare a salt solution with a first mass concentration of c1 and pour it into a saturation cylinder. Place the saturator into the saturation cylinder and read the volume reading on the side wall of the saturation cylinder as V0; Step 2: After the soil sample is filled in the saturator, it is placed in the saturation cylinder again to ensure that the saturation cylinder forms a closed environment. Turn on the vacuum pump to make the saturation cylinder in a negative pressure state. After vacuuming and saturation, read the volume reading of the side wall of the saturation cylinder as V1, and calculate the volume V occupied by the air in the pores of the soil sample. a =V1-V0; Step 3: Take the soil sample out of the saturator and place it in a saturation tank separately to decompose the soil sample in the salt solution; Step 4: Take out the salt solution and measure its mass concentration as c2. Calculate the volume of pore water in the soil sample as V according to the change of mass concentration of the salt solution. w ; Step 5: Calculate the porosity of the soil sample Where V v is the total volume of the soil sample.

2. The soil porosity testing method according to claim 1, characterized in that: The volume V occupied by the pore water in the soil sample described in step 4 w The calculation formula is In the formula, ρ w is the density of the original pore water in the soil sample.

3. The soil porosity testing method according to claim 1, characterized in that: The process of decomposing the soil sample in the salt solution in step 3 is specifically any of the following methods or combinations: The soil sample is stirred by the rotation of the stirring blades in the saturation cylinder; The decomposition of the soil sample is accelerated by shaking the saturated cylinder.

4. The soil porosity testing method according to claim 1, characterized in that: In step 4, the soil sample needs to be separated from the salt solution before the salt solution is taken out. The process of separating the soil sample from the salt solution is specifically as follows: starting the centrifugal device arranged at the bottom of the saturation cylinder, the centrifugal device drives the saturation cylinder to rotate centrifugally, and the soil sample is separated from the salt solution by setting the rotation speed and centrifugal time.

5. The soil porosity testing method according to claim 4, characterized in that: In step 4, after the salt solution is taken out, the salt solution is further filtered and its mass concentration is measured to be c2.

6. The soil porosity testing method according to claim 1, characterized in that: The salt solution is a sodium chloride solution.

7. Soil porosity testing device, characterized in that: include: Saturator, used to hold the soil sample; A saturation cylinder is provided with a stirring blade and a sealing cover, wherein the sealing cover is used to seal the saturation cylinder into a closed environment; A vacuum pump, the vacuum pump is tightly connected to the sealing cover through an exhaust pipe, and is used to make the saturated cylinder in a negative pressure state by vacuuming; A centrifugal device is connected to the base of the saturation cylinder through a transmission device, and is used to drive the saturation cylinder to perform centrifugal rotation.

8. The soil porosity testing device according to claim 7, characterized in that: The saturation cylinder is made of transparent material and has scale lines on its side wall.

9. The soil porosity testing device according to claim 7, characterized in that: The soil porosity testing device also includes an oscillating table, and the bottom of the saturation cylinder is fixedly connected to the top surface of the oscillating table through a support frame.

10. The soil porosity testing device according to claim 7, characterized in that: The side wall of the saturation cylinder is provided with a liquid outlet, and the liquid outlet is matched with a water stop clamp.

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