Aggregate crushing mechanism coupling and individual effect quantitative analysis method

Abstract

The invention provides an aggregate crushing mechanism coupling and independent effect quantitative analysis method. The method comprises the following steps: preliminarily crushing collected undisturbed loose soil into 1t along a soil body crack; the method comprises the following steps: placing 10 mm soil particles in a room for natural air drying, obtaining aggregates with specific particle sizes through a dry screening method, and drying at 40 DEG C until the weight is constant; respectively measuring the particle size distribution characteristics of the aggregate under the conditions of oscillation after rapid wetting, rapid wetting, pre-wetting oscillation and slow wetting, and calculating the average weight diameter of the aggregate; and calculating a relative dissipation index, a relative mechanical crushing index and a relative dissipation mechanical crushing mechanism, further calculating coupling and independent effects of a dissipation effect and a mechanical crushing effect, and evaluating contributions of the dissipation effect and the mechanical crushing effect to the stability of the aggregate. The method can quantitatively analyze the influence of the interaction between different crushing mechanisms on the stability of the aggregate, and provides an effective method for accurately evaluating and researching the stability and internal mechanism of the aggregate, knowing the soil erosion mechanism and optimizing parameters of an erosion forecast model.

Description

Technical Field

[0001] The invention belongs to the fields of soil physics, soil erosion, soil and water conservation test research and soil quality evaluation and management, and specifically relates to a method for evaluating aggregate stability determination and quantitative analysis of fragmentation mechanism. Background Art

[0002] Aggregates are the basic units of soil structure, and their composition and stability regulate soil processes and functions. Aggregate stability is an important indicator of soil quality and an important factor affecting soil erosion. Accurate evaluation of aggregate stability and fragmentation is the basis for guiding soil health management and soil erosion prediction.

[0003] Existing studies have shown that the aggregate fragmentation mechanism under rainfall and irrigation conditions can be divided into dissipation during rapid wetting, mechanical fragmentation caused by raindrop impact and runoff scouring, uneven expansion of clay minerals, and physical-chemical dispersion. At present, there are many methods for determining the water stability of aggregates, such as wet screening, ultrasonic fragmentation, and raindrop impact. However, there are relatively few methods for evaluating the aggregate fragmentation mechanism. Among them, Le Bissonnais proposed an international method to distinguish aggregate fragmentation mechanisms, that is, three pretreatments (rapid wetting, prewetting oscillation, and slow wetting) were used to determine the changes in aggregate stability. In order to distinguish the influence of aggregate destruction mechanisms, Zhang and Horn et al. proposed the relative dissipation index (RSI) and the relative mechanical destruction index (RMI). However, in the process of rainfall erosion in the field, different fragmentation mechanisms (dissipation and mechanical destruction) often occur simultaneously and work together. The existing methods focus on the individual effects of different fragmentation mechanisms and ignore the coupling effects between different fragmentation mechanisms, which deviates from the actual field situation. Therefore, a new method and indicator for quantitatively evaluating the coupling effects of dissipation and mechanical destruction is needed. This is conducive to understanding the aggregate fragmentation mechanism and optimizing the soil erosion prediction model. Summary of the invention

[0004] The purpose of the present invention is to provide a method for evaluating aggregate stability and quantitative analysis of crushing mechanism based on the traditional aggregate crushing mechanism determination method, which helps to more deeply evaluate aggregate stability and its internal mechanism, and at the same time provides an effective means for soil erosion model optimization and soil quality management.

[0005] A method for evaluating the stability of aggregates and quantitative analysis of the fragmentation mechanism, the specific steps are as follows:

[0006] Step (1): collecting undisturbed loose soil in the field, breaking large soil blocks into soil particles <10 mm along the cracks in the soil, placing the soil in a shaded place indoors to naturally air dry until the mass moisture content is less than 5%, and performing agglomerate classification by dry sieving to obtain agglomerates of different particle sizes: 8-10 mm, 5-8 mm, 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm and <0.25 mm, weighing them respectively, calculating the percentage of agglomerates of each particle size, and determining the agglomerate of the particle size to be tested (2-5 mm) according to the agglomerate content;

[0007] Step (2): drying the aggregates of the particle size to be tested in an oven at 40°C for 24-48 hours to ensure that the initial moisture content of aggregates of different soil samples is consistent;

[0008] Step (3): The aggregates to be tested are subjected to four pretreatments, namely, rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting. The specific methods are as follows:

[0009] (i) Rapid wetting and shaking: weigh 5 g of the sample to be tested and quickly immerse the dry aggregate in deionized water. After 10 min, transfer the aggregate into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times;

[0010] (ii) Rapid wetting: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in deionized water, and remove excess water with a pipette after 10 min;

[0011] (iii) Pre-wetting and shaking: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in 95% alcohol, and after 10 min, remove the excess alcohol with a pipette. Transfer the aggregates into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times;

[0012] (iv) Slow wetting: Weigh 5 g of the sample to be tested and place it on a wet filter paper with a suction force of -30 kPa for more than 0.5 h until the aggregates are completely wetted;

[0013] (v) The treated aggregates were transferred onto a sieve with a pore size of 0.05 mm and then immersed in 95% alcohol and moved up and down 20 times with an amplitude of 2 ～ 5cm, and then transfer the crushed agglomerate particles on the sieve to 100 m l beaker, transfer to a 50℃ oven and dry completely;

[0014] Step (4): After drying, the aggregates with a diameter of >0.05 mm are manually sieved and graded, and passed through 2 mm, 1 mm, 0.5 mm, 0.25 mm and 0.10 mm sieves in sequence, and graded and weighed to obtain the percentage of aggregates with a diameter of 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, 0.10-0.25 mm, 0.05-0.10 mm and <0.05 mm, and the average weight diameter (MWD) of the aggregates under different treatment conditions is calculated as follows:

[0015]

[0016] Step (5): Based on the average weight diameter, calculate the relative dissipation index (RSI), relative mechanical damage index (RMI), relative comprehensive crushing index (RSMI), and the individual effect of dissipation (f S ), the single effect of mechanical damage (f M ) and the common effect of the two (f), the calculation process is as follows:

[0017]

[0018] fs=RSI-

[0019] fM=RMI-f

[0020] f=RSI+RMI-RSMI

[0021] Where, MWD FS 、MWD FW 、MWD WS and MWD SW They represent the average weight diameter of aggregates under rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting treatments, respectively.

[0022] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0023] (1) A new method is proposed to quantitatively analyze the interaction between different fragmentation mechanisms of aggregates;

[0024] (2) To provide an effective method for in-depth understanding of the aggregate stability fragmentation mechanism and erosion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 A flow chart of the method for evaluating the stability of aggregates and the determination of the fragmentation mechanism of the present invention;

[0027] Figure 2 It is the mean weight diameter (MWD) diagram of soil in various regions under different treatments of the present invention;

[0028] Figure 3 It is a relative comprehensive damage index (RSMI) diagram of soil in various regions of the present invention;

[0029] Figure 4 This is a graph showing the contribution of different crushing mechanisms to the stability of soil aggregates in various regions of the present invention;

[0030] Figure 5 The figure shows the relationship between aggregate breakage index and splashing amount of red soil in different utilization modes of the present invention.

[0031] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] Example 1

[0033] A method for evaluating the stability of aggregates and quantitative analysis of the fragmentation mechanism, the specific steps are as follows:

[0034] Step (1): collecting undisturbed loose soil in the field, breaking large soil blocks into soil particles <10 mm along the cracks in the soil, placing the soil in a shaded place indoors to naturally air dry until the mass moisture content is less than 5%, and performing agglomerate classification by dry sieving to obtain agglomerates of different particle sizes: 8-10 mm, 5-8 mm, 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm and <0.25 mm, weighing them respectively, calculating the percentage of agglomerates of each particle size, and determining the agglomerate of the particle size to be tested (2-5 mm) according to the agglomerate content (generally selecting large agglomerates with a high content);

[0035] Step (2): drying the aggregates of the particle size to be tested in an oven at 40°C for 24-48 hours to ensure that the initial moisture content of aggregates of different soil samples is consistent;

[0036] Step (3): The aggregates to be tested are subjected to four pretreatments, namely, rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting. The specific methods are as follows:

[0037] (i) Rapid wetting and shaking: weigh 5 g of the sample to be tested and quickly immerse the dry aggregate in deionized water. After 10 min, transfer the aggregate into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times;

[0038] (ii) Rapid wetting: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in deionized water, and remove excess water with a pipette after 10 min;

[0039] (iii) Pre-wetting and shaking: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in 95% alcohol, and after 10 min, remove the excess alcohol with a pipette. Transfer the aggregates into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times;

[0040] (iv) Slow wetting: Weigh 5 g of the sample to be tested and place it on a wet filter paper with a suction force of -30 kPa for more than 0.5 h until the aggregates are completely wetted;

[0041] The treated agglomerates were transferred to a sieve with a pore size of 0.05 mm, and then immersed in 95% alcohol and moved up and down 20 times with an amplitude of 2 to 5 cm. The broken agglomerate particles on the sieve were then transferred to a 100 ml beaker and transferred to a 50°C oven for complete drying.

[0042] Step (4): After drying, the aggregates with a diameter of >0.05 mm are manually sieved and graded, and passed through 2 mm, 1 mm, 0.5 mm, 0.25 mm and 0.10 mm sieves in sequence, and graded and weighed to obtain the percentage of aggregates with a diameter of 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, 0.10-0.25 mm, 0.05-0.10 mm and <0.05 mm, and the average weight diameter (MWD) of the aggregates under different treatment conditions is calculated as follows:

[0043]

[0044] Step (5): Based on the average weight diameter, calculate the relative dissipation index (RSI), relative mechanical damage index (RMI), relative comprehensive crushing index (RSMI), and the individual effect of dissipation (f S ), the single effect of mechanical damage (f M ) and the common effect of the two (f), the calculation process is as follows:

[0045]

[0046] fs=RSI-

[0047] f=RMII-

[0048] f=RSI+RMI-RSMI

[0049] Where, MWD FS 、MWD FW 、MWDWS and MWD SW They represent the average weight diameter of aggregates under rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting treatments, respectively.

[0050] Example 2

[0051] See also Figure 1 In step (1), typical zonal soils were selected. The collection areas from north to south were black soil (Halun City, Heilongjiang Province), brown soil (Luoyang City, Henan Province) and red soil (Changsha City, Hunan Province). For each type of soil, the humus layer (A), sedimentation layer (B) and parent material layer (C) were collected.

[0052] Step (2) The collected soil samples are naturally air-dried, and the aggregates to be tested with a size of 3-5 mm are obtained by dry sieving.

[0053] In this step, after dry sieving, the 3-5 mm aggregate samples to be tested need to be placed in a 40°C oven for 24 hours for pretreatment to control the initial soil moisture content.

[0054] Step (3) The aggregates to be tested are treated with four pretreatment methods, namely, rapid wetting followed by shaking (FS), rapid wetting (FW), prewetting shaking (WS), and slow wetting (SW). The specific methods are as follows: (i) rapid wetting followed by shaking, weigh 5 g of the sample to be tested, and quickly immerse the dry aggregates in deionized water. After 10 minutes, transfer the aggregates into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, add a stopper and cover, and then shake upside down 20 times; (ii) rapid wetting: weigh 5 g of the sample to be tested, and quickly immerse the dry aggregates in deionized water. After 10 minutes, use a pipette to absorb excess water; (ii i) Pre-wetting and shaking: Weigh 5g of the sample to be tested, quickly immerse the dry aggregates in 95% alcohol, and after 10 minutes, use a pipette to absorb the excess alcohol, transfer the aggregates to a 250ml conical flask containing 50ml deionized water, add water to 200ml, seal it with a stopper, and oscillate upside down 20 times; (iv) Slow wetting: Weigh 5g of the sample to be tested, place it on a wet filter paper with a suction force of -30kPa, and leave it for more than 0.5h until the aggregates are completely wet. Transfer the above-treated aggregates to a sieve with a pore size of 0.05mm, and then immerse it in 95% alcohol and move it up and down 20 times with an amplitude of 2 to 5cm. Then transfer the broken aggregate particles on the sieve to a 100ml beaker and transfer it to a 50℃ oven to completely dry.

[0055] Step (4): After drying, the aggregates > 0.05 mm are manually sieved and graded, and passed through 2 mm, 1 mm, 0.5 mm, 0.25 mm and 0.10 mm sieves in turn, and graded and weighed to obtain the percentage of aggregates of 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, 0.10-0.25 mm, 0.05-0.10 mm and <0.05 mm, and the average weight diameter (MWD) of aggregates under different treatment conditions is calculated. The calculation formula is as follows: The calculation formula is as follows:

[0056]

[0057] Step (5): Based on the average weight diameter, calculate the relative dissipation index (RSI), relative mechanical damage index (RMI), relative comprehensive crushing index (RSMI), and the individual effect of dissipation (f S ), the single effect of mechanical damage (f M ) and the common effect of the two (f). The calculation process is as follows:

[0058]

[0059]

[0060] fs=RSI-

[0061] f=RMII-

[0062] f=RSI+RMI-RSMI

[0063] Where, MWD FS 、MWD FW 、MWD WS and MWD SW They represent the average weight diameter of aggregates under rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting treatments, respectively.

[0064] The evaluation criteria for soil aggregate stability are as follows: The higher the RSMI value, the lower its ability to resist the coupling force of dissipation and mechanical destruction. The evaluation criteria for the contribution of dissipation and mechanical destruction mechanisms to aggregate fragmentation are as follows: S 、f M The one with the highest f value is the main mechanism affecting the breakup of soil aggregates.

[0065] Depend on Figure 2 It can be seen that only the black soil B and C layers had no significant difference between the shock treatment (FS) and the rapid wetting treatment (FW), which can be explained by the poor stability of the soil structure and the strong destructive effect can be achieved with a slight destructive force. FSThey are all the lowest among the different treatments in the group, which reflects to varying degrees that the combined force of dissipation and mechanical destruction is greater than the destructive force of dissipation alone.

[0066] Figure 3 The medium RSMI showed that under the coupling of dissipation and mechanical fragmentation, the aggregate stability of red soil layer A and C was the highest, followed by black soil layer A, red soil layer B and brown soil layer A, while black soil layer B and C were the lowest.

[0067] Figure 4 The separate and combined contributions of dissipation and mechanical destruction to aggregate fragmentation are shown, revealing the influence of the two effects on the fragmentation of soil aggregates with different stability.

[0068] Example 3

[0069] A method for evaluating the stability of aggregates and quantitative analysis of the fragmentation mechanism, the specific steps are as follows:

[0070] Step (1): selecting red soil with developed Quaternary clay and sandstone in Nanning, Guangxi, and taking undisturbed loose soil from the surface layer (0-20 cm) of forest land, orchard and cultivated land, breaking large soil blocks into soil particles <10 mm along the cracks of the soil, placing them in a shaded place indoors and naturally air-drying them until the mass moisture content is less than 5%, and performing agglomerate classification by dry sieving to obtain agglomerates of different particle sizes: 8-10 mm, 5-8 mm, 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm and <0.25 mm, weighing them respectively, calculating the percentage of agglomerates of each particle size, and determining the agglomerate of the particle size to be tested (e.g., 2-5 mm) according to the content of the agglomerates (generally, large agglomerates with high content are selected);

[0071] Step (2): drying the aggregates of the particle size to be tested in an oven at 40°C for 24 hours to ensure that the initial moisture content of aggregates of different soil samples is consistent;

[0072] Step (3): The aggregates to be tested are subjected to four pretreatments, namely, rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting. The specific methods are as follows:

[0073] (i) Rapid wetting and shaking: weigh 5 g of the sample to be tested and quickly immerse the dry aggregate in deionized water. After 10 min, transfer the aggregate into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times;

[0074] (ii) Rapid wetting: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in deionized water, and remove excess water with a pipette after 10 min;

[0075] (iii) Pre-wetting and shaking: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in 95% alcohol, and after 10 min, remove the excess alcohol with a pipette. Transfer the aggregates into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times;

[0076] (iv) Slow wetting: Weigh 5 g of the sample to be tested and place it on a wet filter paper with a suction force of -30 kPa for more than 0.5 h until the aggregates are completely wetted; transfer the treated aggregates to a sieve with a pore size of 0.05 mm, and then immerse it in 95% alcohol and move it up and down 20 times with an amplitude of 2 to 5 cm, then transfer the broken aggregate particles on the sieve to a 100 ml beaker and transfer it to a 50°C oven to completely dry;

[0077] Step (4): After drying, the aggregates with a diameter of >0.05 mm are manually sieved and graded, and passed through 2 mm, 1 mm, 0.5 mm, 0.25 mm and 0.10 mm sieves in sequence, and graded and weighed to obtain the percentage of aggregates with a diameter of 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, 0.10-0.25 mm, 0.05-0.10 mm and <0.05 mm, and the average weight diameter (MWD) of the aggregates under different treatment conditions is calculated as follows:

[0078]

[0079] Step (5): Based on the average weight diameter, calculate the relative dissipation index (RSI), relative mechanical damage index (RMI), relative comprehensive crushing index (RSMI), and the individual effect of dissipation (f S ), the single effect of mechanical damage (f M ) and the common effect of the two (f), the calculation process is as follows:

[0080]

[0081] fs=RSI-

[0082] f=RMII--

[0083] f=RSI+RMI-RSMI

[0084] Where, MWD FS 、MWD FW 、MWD WS and MWD SW They represent the average weight diameter of aggregates under rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting treatments, respectively.

[0085] As shown in Table 1, the aggregate fragmentation degree (RSMI) of red soil under the coupling of dissipation and mechanical fragmentation is higher than that of other treatments. Among the different land use types, the aggregate fragmentation degree of forest land is the lowest, and the aggregate fragmentation degree of red soil with sandstone development is higher than that of Quaternary clay, especially cultivated land. S ) made the largest contribution, followed by dissipation and mechanical fragmentation. Moreover, the public contributions of soil dissipation and mechanical fragmentation in orchards and cultivated land were significantly higher than those in forest land.

[0086] Figure 5 It shows that compared with the traditional evaluation indicators of aggregate stability and fragmentation degree (RSI, RMI, RSI×RMI, RSI / RMI), the indicators proposed by the new method (RSMI, f M and f) are better in predicting splash erosion.

[0087] Table 1 Changes in aggregate fragmentation index of laterite red soil under different utilization patterns

[0088]

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the stability of aggregates and quantitative analysis of the fragmentation mechanism, characterized in that The specific steps are as follows: Step (1): collecting undisturbed loose soil in the field, breaking large soil blocks into soil particles <10 mm along the cracks in the soil, placing the soil in a shaded place indoors to naturally air dry until the mass moisture content is less than 5%, and performing agglomerate classification by dry sieving to obtain agglomerates of different particle sizes: 8-10 mm, 5-8 mm, 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm and <0.25 mm, weighing them respectively, calculating the percentage of agglomerates of each particle size, and determining the agglomerate of the particle size to be tested (2-5 mm) according to the agglomerate content; Step (2): drying the aggregates of the particle size to be tested in an oven at 40°C for 24-48 hours to ensure that the initial moisture content of aggregates of different soil samples is consistent; Step (3): The aggregates to be tested are subjected to four pretreatments, namely, rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting. The specific methods are as follows: (i) Rapid wetting and shaking: weigh 5 g of the sample to be tested and quickly immerse the dry aggregate in deionized water. After 10 min, transfer the aggregate into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times; (ii) Rapid wetting: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in deionized water, and remove excess water with a pipette after 10 min; (iii) Pre-wetting and shaking: Weigh 5 g of the sample to be tested, quickly immerse the dry aggregates in 95% alcohol, and after 10 min, remove the excess alcohol with a pipette. Transfer the aggregates into a 250 ml conical flask containing 50 ml of deionized water, add water to 200 ml, seal the flask with a stopper, and shake it upside down 20 times; (iv) Slow wetting: Weigh 5 g of the sample to be tested and place it on a wet filter paper with a suction force of -30 kPa for more than 0.5 h until the aggregates are completely wetted; (v) The crushed aggregates after the above treatment were transferred to a sieve with a pore size of 0.05 mm, and then immersed in 95% alcohol and moved up and down 20 times with an amplitude of 2 to 5 cm. The crushed aggregate particles on the sieve were then transferred to a 100 m l beaker, transfer to a 50℃ oven and dry completely; Step (4): After drying, the aggregates with a diameter of >0.05 mm are manually sieved and graded, and passed through 2 mm, 1 mm, 0.5 mm, 0.25 mm and 0.10 mm sieves in sequence, and graded and weighed to obtain the percentage of aggregates with a diameter of 2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, 0.10-0.25 mm, 0.05-0.10 mm and <0.05 mm, and the average weight diameter (MWD) of the aggregates under different treatment conditions is calculated as follows: Step (5): Based on the average weight diameter, calculate the relative dissipation index (RSI), relative mechanical damage index (RMI), relative comprehensive crushing index (RSMI), and the individual effect of dissipation (f S ), the single effect of mechanical damage (f M ) and the common effect of the two (f), the calculation process is as follows: fs=RSI- f=RMI-- f=RSI+RM-RSMI Where, MWD FS 、MWD FW 、MWD WS and MWD SW They represent the average weight diameter of aggregates under rapid wetting followed by shaking, rapid wetting, pre-wetting shaking, and slow wetting treatments, respectively.

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