Method for calculating clay content of soil body

Abstract

The invention relates to the technical field of soil particle analysis, and discloses a method for calculating the content of clay particles in a soil body, aiming at solving the problem of poor accuracy in the existing method, and the scheme mainly comprises the following steps: adding a dispersing agent into a clay sample filtered by a sieve tray, oscillating and dispersing to prepare a suspension; carrying out particle analysis test on the suspension by adopting a sedimentation analysis method to obtain a particle analysis test result; fitting and establishing a function relationship between the sinking depth and the sinking time of the soil particles in the suspension based on a particle analysis test result; according to the function relationship and based on the Stokes law, calculating the sinking time required for the clay particles to sink to a preset depth; determining the corresponding soil particle mass according to the sinking time required for the clay particles to sink to the preset depth and based on the particle analysis test result, and taking the determined soil particle mass as the clay particle mass in the clay sample; calculating the clay content of the clay sample according to the clay mass. The method improves the accuracy of clay content calculation, and is suitable for soil body analysis.

Description

Technical Field

[0001] The invention relates to the technical field of soil particle analysis, and in particular to a method for calculating the clay content of a soil body. Background Art

[0002] Clay is a mineral particle with extremely small particle size in the soil. As the smallest active component in the soil, the content of clay is the core parameter of soil classification and plays a decisive role in the physical, chemical and engineering properties of the soil. Soil with high clay content is prone to swelling due to water absorption and shrinkage due to water loss, which may cause foundation deformation or soil cracks. It is necessary to strengthen anti-seepage treatment or improve soil quality in engineering; in agriculture, an appropriate amount of clay can enhance the ability to retain water and fertilizer, but too high a content will reduce soil permeability; in the protection of earthen sites, clay content analysis can guide the selection of reinforcement materials to prevent collapse caused by shrinkage and cracking.

[0003] In the prior art, the determination methods of clay content mainly include physical separation method, chemical analysis method and sedimentation method. Among them, the physical separation method mainly separates clay by centrifugation and calculates the content percentage, or combines dispersion treatment (such as boiling method or chemical dispersant) and then screens the coarse particles, and calculates the clay content according to the mass of the remaining soil particles; in this method, high-speed centrifugation may cause the combination of clay and organic matter or binder to be destroyed, thereby underestimating the actual clay content, and the screening method cannot effectively screen clay. The chemical analysis method mainly uses colorimetry or chemical reagent treatment (such as using H 2 O 2 -HCl to remove organic matter and cementing agent) to assist in clay separation and determination; however, when using chemical reagents to remove organic matter, clay minerals (such as vermiculite) may be partially dissolved, resulting in distortion of clay content determination values. Sedimentation methods mainly include hydrometer method and pipette method. The hydrometer method calculates clay content by correcting the hydrometer reading, and the pipette method uses the difference in soil particle sedimentation rate to separate clay particles; the hydrometer method is affected by temperature, dispersant concentration and subjectivity of readings, and is prone to errors, especially at low clay content (<10%). The error is significant, while the pipette method has higher accuracy.

[0004] Application publication number CN117491210A discloses a soil particle analysis method, which discloses a method for determining the percentage of soil particles of different particle sizes in the soil based on the pipette method. The main technical scheme is: the sedimentation time required for soil particles of different particle sizes to freely settle to a preset depth is calculated by Stokes' law, and a certain amount of soil suspension is sucked at a preset depth according to the calculated sedimentation time and weighed, and the content of soil particles smaller than a certain particle size in the sucked suspension is calculated, and then the proportion of soil particles of different particle sizes in the soil sample is calculated. When calculating the settling time required for soil particles of different particle sizes to freely settle to a preset depth, this scheme assumes by default that the soil particles in the suspension sink at a uniform speed, that is, the sinking depth of the soil particles in the suspension is in an ideal linear relationship with the sinking time. The inventors have found through research that the soil particles in the suspension do not sink at a uniform speed, that is, the sinking speed and time of the soil particles in the suspension are not in an ideal linear relationship, but a nonlinear relationship. The settling time of the soil particles is calculated based on the uniform sinking of the soil particles, and the accuracy of the obtained settling time is poor, which leads to the problem of poor accuracy in calculating the proportion of soil particles based on the settling time. Summary of the invention

[0005] The invention aims to solve the problem of poor accuracy in existing methods for determining the clay content of soil, and proposes a method for calculating the clay content of soil.

[0006] The technical solution adopted by the present invention to solve the above technical problems is:

[0007] A method for calculating the clay content of a soil body, the method comprising:

[0008] After the clay sample has been filtered through the sieve plate, a dispersant is added and then dispersed by shaking to prepare a suspension;

[0009] Performing a particle analysis test on the suspension using a sedimentation analysis method to obtain a particle analysis test result, wherein the particle analysis test result includes the sinking depth of soil particles corresponding to different sinking times and the mass of soil particles after drying the suspension sucked by a pipette at a preset depth;

[0010] Based on the particle analysis test results, a functional relationship between the sinking depth and sinking time of soil particles in the suspension is established by fitting;

[0011] Calculating the sinking time required for the clay particles to sink to the preset depth according to the functional relationship and based on Stokes' law;

[0012] Determining the corresponding soil particle mass according to the sinking time required for the clay particles to sink to the preset depth and based on the particle analysis test results, and using the determined soil particle mass as the clay particle mass in the clay sample;

[0013] The clay content of the clay sample is calculated based on the clay mass, the total mass of the clay sample, the total volume of the suspension and the volume of the suspension aspirated by the pipette.

[0014] Furthermore, the functional relationship between the sinking depth and sinking time of the soil particles is:

[0015]

[0016] Where L is the sinking depth of soil particles, t is the sinking time of soil particles, W and K m Represents a characteristic constant.

[0017] Furthermore, the Stokes' law is as follows:

[0018]

[0019] The calculation formula for the sinking time required for the clay particles to sink to the preset depth is as follows:

[0020]

[0021] Where v represents the sinking velocity of clay particles, ρ s represents the density of clay particles, ρ w represents the density of water at 4°C, η represents the viscosity coefficient of water, g represents the acceleration of gravity, d represents the particle size of clay particles, and t i Indicates the sinking time corresponding to the clay particles.

[0022] Furthermore, the particle size of the clay particles is less than or equal to 0.005 mm.

[0023] Furthermore, the method of determining the corresponding soil particle mass based on the sinking time required for the clay particles to sink to the preset depth and based on the particle analysis test results specifically includes calculating the corresponding soil particle mass using a linear interpolation method, and the calculation formula is as follows:

[0024]

[0025] Among them, m dx represents the mass of soil particles corresponding to the sinking time required for clay particles to sink to the preset depth, t i represents the sinking time corresponding to the clay particles, t i-1 and t i+1 Indicates the two adjacent sinking times corresponding to the clay particles in the particle analysis test results, m di-1 and m di+1 Respectively represent the two adjacent sinking times t in the particle analysis test results i-1 and t i+1 The corresponding soil particle mass.

[0026] Furthermore, the calculation formula of the clay content is as follows:

[0027]

[0028] Where X represents the clay content of the clay sample, m dx Represents the mass of clay particles in the clay sample, m d represents the total mass of the clay sample, V represents the total volume of the suspension, and V x Indicates the volume of suspension aspirated by the pipette.

[0029] Furthermore, a particle analysis test is performed on the suspension using a sedimentation analysis method, specifically including:

[0030] At different sinking times, a suspension sinking meter is used to measure the sinking depth of soil particles in the suspension, and a pipette is used to suck the suspension of a preset depth. The sucked suspension is dried, and the dried soil particles are weighed to obtain the corresponding soil particle mass.

[0031] Furthermore, the dispersant is sodium hexametaphosphate.

[0032] Furthermore, the preset depth is 10 cm.

[0033] Furthermore, the sieve plate used to filter the clay sample had a pore size of 0.075 mm.

[0034] The beneficial effects of the present invention are as follows: the method for calculating the clay content of a soil body provided by the present invention adopts a sedimentation method to determine the clay content, which improves the accuracy of calculating the clay content compared with a physical separation method and a chemical analysis method; and, according to the particle analysis test results, the present invention fits the real functional relationship between the sinking depth and the sinking time of soil particles in a suspension, calculates the sinking time required for the clay to sink to a preset depth according to the functional relationship and based on Stokes' law, thereby improving the accuracy of calculating the sinking time, and further improving the accuracy of calculating the clay content; in addition, the present invention calculates the clay content according to the calculated sinking time and the particle analysis test results, thereby further improving the accuracy of calculating the clay content. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a flow chart for calculating the clay content of a soil body provided in an embodiment;

[0036] Figure 2 A schematic diagram of a particle analysis test process provided in an embodiment;

[0037] Figure 3 A schematic diagram of a correlation curve between the sinking depth and sinking time of soil particles in a suspension provided in an embodiment;

[0038] Figure 4 The diagram is a schematic diagram of the relationship between the logarithm of the sinking time of soil particles in the suspension provided in the embodiment and the mass of the soil particles after the suspension is dried. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution in this embodiment will be clearly and completely described below in conjunction with the drawings in this embodiment.

[0040] In some processes described in the specification of the present invention and the above-mentioned drawings, multiple operations appearing in a specific order are included, but it should be clearly understood that these operations may not be executed in the order in which they appear in this document or may be executed in parallel. The serial numbers of the operations are only used to distinguish between different operations, and the serial numbers themselves do not represent any execution order; in addition, these processes may include more or fewer operations, and these operations may be executed sequentially or in parallel.

[0041] The technical solution of the present invention is applicable to application scenarios of soil clay content analysis, such as foundation soil, agricultural soil, and soil heritage protection.

[0042] In the current method of analyzing the clay content of soil using the sedimentation method, it is generally believed that the soil particles in the suspension descend at a uniform rate; however, the inventors have found through research that the soil particles in the suspension do not descend at a uniform rate. The method of analyzing the clay content of soil based on the uniform sinking of soil particles has the problem of poor accuracy.

[0043] Based on this, the technical scheme of the present invention is proposed. In the present invention, a dispersant is added to a clay sample filtered through a sieve plate, and the mixture is dispersed by shaking to prepare a suspension. A particle analysis test is performed on the suspension using a sedimentation analysis method to obtain a particle analysis test result, wherein the particle analysis test result includes the sinking depth of soil particles corresponding to different sinking times and the mass of soil particles after drying of the suspension sucked by a pipette at a preset depth. A functional relationship between the sinking depth and the sinking time of soil particles in the suspension is established by fitting based on the particle analysis test result. The sinking time required for the clay particles to sink to the preset depth is calculated based on the functional relationship and based on Stokes' law. The corresponding soil particle mass is determined based on the sinking time required for the clay particles to sink to the preset depth and based on the particle analysis test result, and the determined soil particle mass is used as the clay mass in the clay sample. The clay content of the clay sample is calculated based on the clay mass, the total mass of the clay sample, the total volume of the suspension and the volume of the suspension sucked by the pipette.

[0044] Specifically, the present invention first prepares a clay sample into a suspension, and performs a particle analysis test on the suspension, records the sinking depths of soil particles corresponding to different sinking times, and records the mass of soil particles after drying the suspension sucked by a pipette at a preset depth corresponding to different sinking times; then, according to the sinking depths of soil particles corresponding to different sinking times in the particle analysis test results, the real functional relationship between the sinking depth and the sinking time of soil particles in the suspension is fitted, and then the sinking time required for the clay particles to sink to the preset depth is calculated according to the functional relationship and Stokes' law; then, according to the calculated sinking time and based on the mass of soil particles corresponding to different sinking times in the particle analysis test results, the corresponding clay mass is calculated; finally, the clay content percentage of the clay sample is calculated according to the clay mass. Compared with the physical separation method and chemical analysis method in the prior art, the present invention improves the accuracy of clay content calculation; and, the present invention calculates the sinking time required for the clay to sink to a preset depth through a fitted functional relationship, thereby improving the accuracy of sinking time calculation, and further improving the accuracy of clay content calculation; in addition, the present invention calculates the clay content based on the particle analysis test results, further improving the accuracy of clay content calculation.

[0045] The technical solution in this embodiment will be clearly and completely described below in conjunction with the drawings in this embodiment. Obviously, the described embodiment is only a part of the embodiments of the present invention, rather than all the embodiments.

[0046] Figure 1 A flow chart showing a method for calculating the clay content of soil is shown in Figure 1 , the method comprises the following steps:

[0047] Step 1: Add the dispersant to the clay sample filtered through the sieve plate, shake and disperse it to make a suspension.

[0048] In practical applications, the clay sample can be filtered through a sieve plate with a pore size of 0.075 mm, and then a dispersant is added to prepare a suspension, and the dispersant can be sodium hexametaphosphate.

[0049] Step 2: Perform a particle analysis test on the suspension using a sedimentation analysis method to obtain particle analysis test results, which include the sinking depth of soil particles corresponding to different sinking times and the mass of soil particles after drying the suspension sucked by a pipette at a preset depth.

[0050] See also Figure 2 In practical applications, the sinking depth of soil particles in the suspension can be measured at different sinking times using a suspension sinking meter, and the suspension of a preset depth can be sucked with a pipette, the sucked suspension can be dried, and the dried soil particles can be weighed to obtain the sinking depth and soil particle mass corresponding to different sinking times.

[0051] In this embodiment, 30 g of clay sample was filtered through a sieve plate with a pore size of 0.075 mm, and then a dispersant was added and shaken to disperse to prepare a suspension with a total volume of V = 1000 mL. Then, at different sinking times (0, t1, t2, t3, ...) of the suspension, the sinking depth of the soil particles in the suspension was measured, and the mass of the soil particles after the suspension at a depth of 10 cm was sucked by a pipette and dried was recorded to obtain the particle analysis test results shown in Table 1.

[0052] Table 1 - Particle analysis test results

[0053]

[0054] Step 3: Based on the particle analysis test results, a functional relationship between the sinking depth and sinking time of soil particles in the suspension is established by fitting.

[0055] Based on the results of particle analysis tests, it can be found that the sedimentation law of soil particles in suspension conforms to the sedimentation theory of soil mechanics suspension, but the sedimentation speed of soil particles in suspension is not uniform. Figure 3 According to the results of the particle analysis test, the correlation curve between the sinking time and the sinking depth of the soil particles in the suspension can be fitted. By analyzing the correlation curve between the sinking time and the sinking depth, it can be found that the curve basically conforms to the law of the Michaelis-Menten equation curve. The Michaelis-Menten equation represents a hyperbola.

[0056] Based on this, this embodiment establishes the functional relationship between the sinking time and sinking depth of soil particles (including clay particles) in the suspension by fitting the particle analysis test results, as follows:

[0057]

[0058] Where L is the sinking depth of soil particles (cm), t is the sinking time of soil particles (min), W and K m represents the characteristic constant, which is calculated by regression following the Michaelis-Menten equation.

[0059] This embodiment uses the particle analysis test results in Table 1, and the function relationship obtained by fitting is as follows:

[0060]

[0061] Step 4: Calculate the sinking time required for the clay particles to sink to the preset depth according to the functional relationship and based on Stokes' law.

[0062] It can be understood that Stokes' law can be used to calculate the settling velocity of soil particles in fluids. The expression for calculating the settling velocity of clay particles in suspension using Stokes' law can be:

[0063]

[0064] Where v represents the sinking velocity of clay particles, ρ s Indicates the density of clay particles (g / cm 3 ), ρ w Indicates the density of water at 4°C (g / cm 3 ), η represents the viscosity coefficient of water (1×10 -6 kpa·s), g represents the acceleration due to gravity (981 cm / s 2 ), d represents the particle size of clay particles (mm).

[0065] By establishing an integral equation, the calculation formula for the sinking time required for the clay to sink to the preset depth can be derived, namely:

[0066]

[0067] Among them, t i Indicates the sinking time (min) required to sink to the preset depth.

[0068] In practical applications, the density and particle size of the clay particles are substituted into the above formula to calculate the sinking time required for the clay particles to sink to the preset depth. In this embodiment, soil particles with a particle size less than or equal to 0.005 mm are used as clay particles, that is, d = 0.005 mm, and the above formula is substituted to obtain the sinking time t required for the clay particles to sink to a depth of 10 cm. i =64.43min.

[0069] Step 5: Determine the corresponding soil particle mass according to the sinking time required for the clay particles to sink to the preset depth and based on the particle analysis test results, and use the determined soil particle mass as the clay particle mass in the clay sample.

[0070] Based on the particle analysis test results, a corresponding relationship table between the logarithm of the sinking time of the soil particles in the suspension and the mass of the soil particles after absorbing the suspension and drying can be obtained, please refer to Table 2.

[0071] Table 2 - Corresponding relationship between the logarithm of the sinking time and the mass of the soil particles after absorbing the suspension and drying

[0072]

[0073]

[0074] See also Figure 4According to the corresponding relationship table shown in Table 2, the corresponding relationship between the logarithm of the sinking time of the soil particles in the suspension and the mass of the soil particles after absorbing the suspension and drying can be obtained. By constructing the corresponding relationship by taking the logarithm of the sinking time, the calculation complexity is reduced, the numerical overflow or underflow problem is avoided, thereby simplifying the operation and improving the calculation efficiency.

[0075] According to the correspondence between the logarithm of the sinking time of the soil particles in the suspension and the mass of the soil particles after absorbing the suspension and drying it, the interpolation method can be used to calculate the mass of the soil particles after absorbing the suspension and drying it corresponding to the sinking time required for the clay particles to sink to the preset depth, and use it as the mass of the clay particles. The calculation formula is as follows:

[0076]

[0077] Among them, m dx represents the mass of soil particles corresponding to the sinking time required for clay particles to sink to the preset depth, t i represents the sinking time corresponding to the clay particles, t i-1 and t i+1 Indicates the two adjacent sinking times corresponding to the clay particles in the particle analysis test results, m di-1 and m di+1 Respectively represent the two adjacent sinking times t in the particle analysis test results i-1 and t i+1 The corresponding soil particle mass.

[0078] Based on the particle analysis results shown in Table 1, it is assumed that the sinking time t required for the clay to sink to a depth of 10 cm is calculated. i = 64.43min, then in the particle analysis test results, the two adjacent sinking times are 50min and 120min, that is, t i-1 =50min,t i+1 = 120min, the corresponding mass of soil particles after absorbing the suspension and drying is 7.5mg and 5.5mg respectively, that is, m di-1 =7.5mg, m di+1 =5.5mg, substitute the above data into the formula to calculate the mass of soil particles corresponding to the clay particles sinking to a depth of 10cm:

[0079]

[0080] Step 6: Calculate the clay content of the clay sample based on the mass of the clay, the total mass of the clay sample, the total volume of the suspension and the volume of the suspension aspirated by the pipette.

[0081] In this embodiment, the calculation formula of clay content is as follows:

[0082]

[0083] Where, X represents the clay content of the clay sample (%), m dx represents the mass of clay particles in the clay sample (mg), m d represents the total mass of the clay sample (mg), V represents the total volume of the suspension (mL), and V x Indicates the volume of suspension aspirated by the pipette (mL).

[0084] Assume that the mass m of clay particles in the clay sample calculated in step 5 is dx =6.08 mg, the total mass of the clay sample m d = 30 g, the total volume of the suspension V = 1000 mL, the volume of the suspension sucked by the pipette V x =25mL, substitute the above data into the formula to calculate the clay content of the clay sample:

[0085]

[0086] In summary, this embodiment adopts the sedimentation method to determine the clay content, which improves the accuracy of the clay content calculation compared with the physical separation method and the chemical analysis method; and, this embodiment fits the true functional relationship between the sinking depth and the sinking time of the soil particles in the suspension according to the particle analysis test results, and calculates the sinking time required for the clay to sink to a preset depth according to the functional relationship and based on Stokes' law, thereby improving the accuracy of the sinking time calculation, and further improving the accuracy of the clay content calculation; in addition, this embodiment calculates the clay content according to the calculated sinking time and the particle analysis test results, further improving the accuracy of the clay content calculation.

Claims

1. A method for calculating the clay content of soil, characterized in that: The method comprises: After the clay sample has been filtered through the sieve plate, a dispersant is added and then dispersed by shaking to prepare a suspension; Performing a particle analysis test on the suspension using a sedimentation analysis method to obtain a particle analysis test result, wherein the particle analysis test result includes the sinking depth of soil particles corresponding to different sinking times and the mass of soil particles after drying the suspension sucked by a pipette at a preset depth; Based on the particle analysis test results, a functional relationship between the sinking depth and sinking time of soil particles in the suspension is established by fitting; Calculating the sinking time required for the clay particles to sink to the preset depth according to the functional relationship and based on Stokes' law; Determining the corresponding soil particle mass according to the sinking time required for the clay particles to sink to the preset depth and based on the particle analysis test results, and using the determined soil particle mass as the clay particle mass in the clay sample; The clay content of the clay sample is calculated based on the clay mass, the total mass of the clay sample, the total volume of the suspension and the volume of the suspension aspirated by the pipette.

2. The method for calculating the clay content of soil according to claim 1, characterized in that: The functional relationship between the sinking depth and sinking time of the soil particles is: Where L is the sinking depth of soil particles, t is the sinking time of soil particles, W and K m Represents a characteristic constant.

3. The method for calculating the clay content of soil according to claim 2, characterized in that: The Stokes' law is as follows: The calculation formula for the sinking time required for the clay particles to sink to the preset depth is as follows: Where v represents the sinking velocity of clay particles, ρ s represents the density of clay particles, ρ w represents the density of water at 4°C, η represents the viscosity coefficient of water, g represents the acceleration of gravity, d represents the particle size of clay particles, and t i Indicates the sinking time corresponding to the clay particles.

4. The method for calculating the clay content of soil according to claim 3, characterized in that: The particle size of the clay particles is less than or equal to 0.005 mm.

5. The method for calculating the clay content of soil according to claim 1, characterized in that: The method of determining the corresponding soil particle mass based on the sinking time required for the clay particles to sink to the preset depth and the particle analysis test results specifically includes calculating the corresponding soil particle mass using a linear interpolation method, and the calculation formula is as follows: Among them, m dx represents the mass of soil particles corresponding to the sinking time required for clay particles to sink to the preset depth, t i represents the sinking time corresponding to the clay particles, t i-1 and t i+1 Indicates the two adjacent sinking times corresponding to the clay particles in the particle analysis test results, m di-1 and m di+1 Respectively represent the two adjacent sinking times t in the particle analysis test results i-1 and t i+1 The corresponding soil particle mass.

6. The method for calculating the clay content of soil according to claim 1, characterized in that: The calculation formula of the clay content is as follows: Where X represents the clay content of the clay sample, m dx Represents the mass of clay particles in the clay sample, m d represents the total mass of the clay sample, V represents the total volume of the suspension, and V x Indicates the volume of suspension aspirated by the pipette.

7. The method for calculating the clay content of soil according to claim 1, characterized in that: The particle analysis test of the suspension is carried out by sedimentation analysis method, including: At different sinking times, a suspension sinking meter is used to measure the sinking depth of soil particles in the suspension, and a pipette is used to suck the suspension of a preset depth. The sucked suspension is dried, and the dried soil particles are weighed to obtain the corresponding soil particle mass.

8. The method for calculating the clay content of soil according to claim 1, characterized in that: The dispersant is sodium hexametaphosphate.

9. The method for calculating the clay content of soil according to claim 1, characterized in that: The preset depth is 10 cm.

10. The method for calculating the clay content of soil according to claim 1, characterized in that: The sieve plate used to filter the clay sample had a pore size of 0.075 mm.

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