Roadbed solid waste modified soil tensile strength estimation method considering freeze-thaw cycle

Abstract

The invention belongs to the technical field of road engineering, and particularly relates to a roadbed solid waste modified soil tensile strength estimation method considering freeze-thaw cycle, which comprises the following steps: determining the maximum dry density and optimal water content of solid waste under different W / C conditions through a heavy compaction test; the method comprises the following steps: preparing a sample, and putting the sample into a high-low temperature alternating testing machine for freezing and thawing cycle treatment; then carrying out a tensile test; and finally, comparing and analyzing the tensile strength corresponding to the solid waste under different working conditions, and establishing a tensile strength estimation model comprehensively considering the solid waste clay ratio, the relative compactness, the saturation degree and the freezing and thawing cycle number. By comprehensively considering the influence of factors such as gradation variables, compactness variables, humidity variables and environment variables on the tensile strength, rapid prediction of the tensile strength of the solid waste material under different conditions is realized, the model is clear in physical significance and simple in structure, the test difficulty is reduced, obvious engineering convenience is provided for units without test conditions, and the test efficiency is improved. High market popularization values are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of road engineering and relates to a method for estimating the tensile strength of roadbed solid waste modified soil taking freeze-thaw cycles into consideration. Background Art

[0002] With the intensification of global climate change, freeze-thaw cycles are becoming increasingly frequent in cold regions. Freeze-thaw cycles refer to the repeated freezing and thawing of soil, a phenomenon that significantly affects the mechanical properties of soil, especially its tensile strength. Tensile strength is the ability of soil to resist damage under tensile stress and is a key indicator for evaluating soil stability and bearing capacity. However, freeze-thaw cycles can cause damage to the soil's internal structure, such as changes in pore structure and water redistribution, significantly reducing the soil's tensile strength and, in turn, affecting the safety and stability of soil engineering.

[0003] As an environmentally friendly waste disposal method, the resource utilization of solid waste has shown great application prospects in soil improvement. Incorporating solid waste materials into soil can not only improve the engineering properties of the soil, but also reduce engineering costs and environmental pollution risks. However, existing research has mainly focused on the mechanical properties of roadbed solid waste at room temperature or in conventional environments. There is a relative lack of research on the performance of roadbed solid waste under freeze-thaw cycles in cold regions. In particular, the changing patterns and influencing mechanisms of the tensile strength of roadbed solid waste after freeze-thaw cycles are still unclear, which poses a challenge to soil engineering design in cold regions.

[0004] Generally speaking, it is a conventional method to calculate the tensile strength using the soil shear strength index or shear strength envelope. However, considering that the shear test process is cumbersome, time-consuming, and requires professional personnel to operate, it is necessary to use a more convenient and rapid method to obtain the tensile strength of the soil under different working conditions. In response to the above problems, it is of great theoretical and practical significance to study the variation law of the tensile strength of roadbed solid waste under the action of freeze-thaw cycles. By taking into account the influence of freeze-thaw cycles, the tensile strength of roadbed solid waste can be more accurately estimated, providing a scientific basis and technical support for soil engineering in cold areas. This not only helps to improve the stability and durability of engineering structures, but also promotes the widespread application of solid waste resource utilization in cold areas. Therefore, a method for estimating the tensile strength of roadbed solid waste-modified soil considering freeze-thaw cycles is proposed, which has important research value and broad application prospects. Summary of the Invention

[0005] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles described in the present invention, the estimation method comprising the following steps:

[0007] S1: A new quantitative analysis index for the physical gradation of solid waste, namely the solid-waste-to-clay ratio, is proposed. Based on this, the maximum dry density and optimal moisture content of solid waste under different W / C conditions are determined through heavy compaction tests.

[0008] S2: Based on the heavy compaction test results of step S1, samples with relative densities of 0.87, 0.9, 0.93, and 0.96 and saturations of 25%, 50%, 75%, and 100% are prepared; after sample preparation, the samples are placed in a high-low temperature alternating tester for freeze-thaw cycle treatment. To ensure the stability of the internal moisture content of the samples during the freeze-thaw process, the samples are wrapped with plastic wrap until the freeze-thaw process is completed;

[0009] S3: After the freeze-thaw cycle treatment in step S2 is completed, the electric stretching rod is connected to the threaded hole of the convex mold, and the stretching base is connected to the threaded hole of the concave mold; then, the electric stretching rod is controlled by a computer and a servo control switch to perform a tensile test at a stretching rate of 0.5 mm / min;

[0010] S4: Based on the tensile test results of step S3, the tensile strength of solid waste under different working conditions is compared and analyzed, and a tensile strength estimation model is established that comprehensively considers the solid waste clay ratio, relative density, saturation and number of freeze-thaw cycles; then, the test data of step S3 are fitted by the stepwise regression analysis method of SAS software to obtain the model parameters a1-a8.

[0011] Preferably, the heavy compaction test in S1 comprises the following steps:

[0012] S101: Drying the solid waste and clay required for the compaction test for 24 hours;

[0013] S102: Preset W / C material configuration;

[0014] S103: The moisture content of the material is adjusted with a gradient difference of 2%, and the material is subjected to a 18-hour suffocation treatment to make the internal humidity uniform;

[0015] S104: After the filling is completed, the mixed filler is compacted in three layers using a heavy compaction method, with each layer compacted 98 times;

[0016] S105: The central portion of the molded sample is selected to measure the moisture content and dry density, thereby obtaining the maximum dry density and optimal moisture content of the solid waste under different W / C conditions.

[0017] Preferably, the sample preparation in S2 comprises the following steps:

[0018] S201: Using a hoop to connect the threaded hole of the inner concave mold and the threaded hole of the outer convex mold, thereby achieving connection and fixation at the mortise and tenon of the inner concave mold and the outer convex mold;

[0019] S202: Place an outer pressure-bearing component on the upper side of the concave mold and the convex mold, and a pressure-bearing pad on the lower side, and place a disposable filter paper between the sample and the component and the pad to prevent damage to the sample when the component is removed;

[0020] S203: The electric stretching rod and the loading plate are controlled by the computer and the servo control switch to vibrate the outer pressure-bearing component to prepare the sample. When the outer pressure-bearing component reaches a preset height, the loading is stopped.

[0021] Preferably, the formula for the solid waste to clay ratio in S1 is:

[0022]

[0023]

[0024] Where: W / C is the solid waste clay ratio; S max is the maximum screening size of solid waste (mm); k is the shape parameter of the physical gradation state; S f The aperture is f i The cumulative pass rate corresponding to the sieve holes (%); f i is the sieve hole diameter (mm).

[0025] Preferably, in the freeze-thaw cycle treatment in S2, the sample is frozen at a temperature of -20°C for 12 hours; and then thawed at a temperature of 20°C for 12 hours.

[0026] Preferably, the number of freeze-thaw cycles in the freeze-thaw cycle treatment in S2 is selected as 0, 1, 3, 6 and 10 by increasing the difference backward.

[0027] Preferably, the tensile strength estimation model in S4 is expressed as follows:

[0028]

[0029] Where: S t is the tensile strength; W / C is the solid waste clay ratio; R c is the relative density; N FT is the number of freeze-thaw cycles; D s is the saturation; e is the mathematical constant 2.718; a1-a8 are model parameters.

[0030] Preferably, the tensile strength estimation model in S4 adopts robustness verification, and the robustness verification draws a robustness verification scatter plot with the measured value of the tensile strength as the horizontal axis and the estimated value as the vertical axis.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. The present invention discloses a method for estimating the tensile strength of roadbed solid waste-modified soil that takes freeze-thaw cycles into consideration. By comprehensively considering the effects of factors such as grading variables, density variables, humidity variables, and environmental variables on its tensile strength, the method achieves rapid prediction of the tensile strength of solid waste materials under different conditions. Furthermore, the model has clear physical meaning and a simple structure. It only requires inputting the corresponding working conditions into the model to obtain the tensile strength value of the solid waste material under the coupling effect of the corresponding working conditions. This method greatly reduces the time and difficulty of testing, provides significant engineering convenience for units that do not have the necessary testing conditions, and has high market promotion value.

[0033] 2. The present invention discloses a method for estimating the tensile strength of roadbed solid waste-modified soil that takes freeze-thaw cycles into consideration. The method comprises the following steps: drying the solid waste and clay required for the compaction test for 24 hours; adjusting the moisture content of the material with a gradient difference of 2%, and performing an 18-hour stuffing treatment to uniformize the internal humidity; after the stuffing is completed, the mixed filler is compacted in three layers using a heavy compaction method, with each layer compacted 98 times; and the moisture content and dry density of the central portion of the molded sample are measured to obtain the maximum dry density and optimal moisture content of the solid waste under different W / C conditions, thereby facilitating rapid sample preparation.

[0034] 3. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles described in the present invention has been verified for robustness. The robustness of the constructed model is verified by the tensile test results of the working conditions. A robustness verification scatter plot is drawn with the measured tensile strength value as the horizontal axis and the estimated value as the vertical axis, ensuring that the new model has high accuracy and applicability, and can be extended to the same type of materials, as well as the tensile strength estimation of the same material under other working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings.

[0036] Figure 1 This is a flow chart of a method for estimating tensile strength according to an embodiment of the present invention;

[0037] Figure 2 This is a flow chart of a heavy compaction test method according to an embodiment of the present invention;

[0038] Figure 3 This is a flow chart of a sample preparation method according to an embodiment of the present invention;

[0039] Figure 4This is a graph showing the results of a heavy impact test in one embodiment of the present invention;

[0040] Figure 5 This is a graph showing the relationship between different W / C ratios and tensile strength in one embodiment of the present invention;

[0041] Figure 6 is a graph showing the relationship between relative density and tensile strength of an embodiment of the present invention;

[0042] Figure 7 is a graph showing the relationship between different saturations and tensile strength in one embodiment of the present invention;

[0043] Figure 8 is a graph showing the relationship between the number of freeze-thaw cycles and the tensile strength in one embodiment of the present invention;

[0044] Figure 9 is a scatter plot of robustness verification results in one embodiment of the present invention; DETAILED DESCRIPTION

[0045] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0046] like Figure 1 As shown, a method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to an embodiment of the present invention includes the following steps:

[0047] S1: A new quantitative analysis index for the physical gradation of solid waste, namely the solid-waste-to-clay ratio, is proposed. Based on this, the maximum dry density and optimal moisture content of solid waste under different W / C conditions are determined through heavy compaction tests.

[0048] S2: Based on the heavy compaction test results of step S1, samples with relative densities of 0.87, 0.9, 0.93, and 0.96 and saturations of 25%, 50%, 75%, and 100% are prepared; after sample preparation, the samples are placed in a high-low temperature alternating tester for freeze-thaw cycle treatment. To ensure the stability of the internal moisture content of the samples during the freeze-thaw process, the samples are wrapped with plastic wrap until the freeze-thaw process is completed;

[0049] S3: After the freeze-thaw cycle treatment in step S2 is completed, the electric stretching rod is connected to the threaded hole of the convex mold, and the stretching base is connected to the threaded hole of the concave mold; then, the electric stretching rod is controlled by a computer and a servo control switch to perform a tensile test at a stretching rate of 0.5 mm / min;

[0050] S4: Based on the tensile test results of step S3, the tensile strength of solid waste under different working conditions is compared and analyzed, and a tensile strength estimation model is established that comprehensively considers the solid waste clay ratio, relative density, saturation and number of freeze-thaw cycles; then, the test data of step S3 are fitted by the stepwise regression analysis method of SAS software to obtain the model parameters a1-a8.

[0051] The estimation method provided by the present invention proposes a new quantitative analysis indicator for the physical gradation of solid waste: the solid-waste-to-clay ratio. Based on this indicator, the maximum dry density and optimal moisture content of the solid waste under different W / C conditions are determined through heavy compaction tests in accordance with the "Highway Geotechnical Test Regulations."

[0052] Then, based on the compaction test results, samples with relative densities of 0.87, 0.9, 0.93, and 0.96 and saturations of 25%, 50%, 75%, and 100% were prepared. After sample preparation, the samples were placed in a high-low temperature alternating tester for freeze-thaw cycle treatment. To ensure the stability of the internal moisture content of the samples during the freeze-thaw process, the samples were wrapped with plastic wrap until the freeze-thaw process was completed.

[0053] After the freeze-thaw cycle treatment is completed, the electric stretching rod is connected to the threaded hole of the convex mold, and the stretching base is connected to the threaded hole of the concave mold. Then, the electric stretching rod is controlled by the computer and servo control switch to perform a tensile test at a stretching rate of 0.5 mm / min.

[0054] Based on the tensile test results, the tensile strength of solid waste under different working conditions was compared and analyzed, and a tensile strength estimation model was established that comprehensively considered the solid waste clay ratio, relative density, saturation, and number of freeze-thaw cycles. Then, the test data from step S3 were fitted using the stepwise regression analysis method of SAS software to obtain model parameters a1-a8. This fitting step is a conventional method and will not be repeated here. In addition, to verify the accuracy and applicability of the model established in this paper, tensile test results under different working conditions were selected to verify the robustness of the established model.

[0055] The core of this method is to predict the tensile strength of solid waste materials under specific conditions through experiments and computational models, thereby providing a scientific basis for roadbed construction and management; by comprehensively considering the influence of factors such as grading variables, density variables, humidity variables and environmental variables on their tensile strength, the tensile strength of solid waste materials under different conditions can be quickly predicted; at the same time, the model has clear physical meaning and simple structure. It only needs to input the corresponding working conditions into the model to obtain the tensile strength value of the solid waste material under the coupling effect of the corresponding working conditions, which greatly reduces the test time and difficulty, provides obvious engineering convenience for units that do not have the test conditions, and has high market promotion value.

[0056] like Figure 2 and Figure 4 As shown, the heavy compaction test in S1 includes the following steps:

[0057] S101: Drying the solid waste and clay required for the compaction test for 24 hours;

[0058] S102: Preset W / C material configuration;

[0059] S103: The moisture content of the material is adjusted with a gradient difference of 2%, and the material is subjected to a 18-hour suffocation treatment to make the internal humidity uniform;

[0060] S104: After the filling is completed, the mixed filler is compacted in three layers using a heavy compaction method, with each layer compacted 98 times;

[0061] S105: The central portion of the molded sample is selected to measure the moisture content and dry density, thereby obtaining the maximum dry density and optimal moisture content of the solid waste under different W / C conditions.

[0062] When the compaction test provided by the present invention is used, the solid waste and clay required for the compaction test are first dried for 24 hours; the material configuration with different W / C ratios (1, 1.5, 2, 2.5) is preset; the moisture content of the material is then configured with a gradient difference of 2%, and the material is subjected to an 18-hour stuffing treatment to uniformize the internal humidity; after the stuffing is completed, the mixed filler is compacted in three layers using a heavy compaction method, with each layer compacted 98 times; the moisture content and dry density of the central part of the molded sample are measured to obtain the maximum dry density and optimal moisture content of the solid waste under different W / C conditions.

[0063] like Figure 3 As shown, the sample preparation in S2 includes the following steps:

[0064] S201: Using a hoop to connect the threaded hole of the inner concave mold and the threaded hole of the outer convex mold, thereby achieving connection and fixation at the mortise and tenon of the inner concave mold and the outer convex mold;

[0065] S202: Place an outer pressure-bearing component on the upper side of the concave mold and the convex mold, and a pressure-bearing pad on the lower side, and place a disposable filter paper between the sample and the component and the pad to prevent damage to the sample when the component is removed;

[0066] S203: The electric stretching rod and the loading plate are controlled by the computer and the servo control switch to vibrate the outer pressure-bearing component to prepare the sample. When the outer pressure-bearing component reaches a preset height, the loading is stopped.

[0067] When the sample provided by the present invention is used, a hoop is first used to connect the threaded hole of the inner concave mold and the threaded hole of the outer convex mold, and the inner concave mold and the outer convex mold are fixed by the connection at the mortise and tenon; an outer pressure-bearing element is placed on the upper side of the inner concave mold and the outer convex mold, and a pressure-bearing pad is placed on the lower side, and a disposable filter paper is placed between the sample and the element and the pad to prevent the sample from being damaged when the element is disassembled; finally, the electric stretching rod and the loading plate are controlled by the computer and the servo control switch to vibrate the outer pressure-bearing element to prepare the sample. When the outer pressure-bearing element reaches a preset height, the loading is stopped and the sample preparation is completed.

[0068] like Figure 4 As shown, the formula for the solid waste-to-clay ratio in S1 is:

[0069]

[0070]

[0071] Where: W / C is the solid waste clay ratio; S max is the maximum screening size of solid waste (mm); k is the shape parameter of the physical gradation state; S f The aperture is f i The cumulative pass rate corresponding to the sieve holes (%); f i is the sieve hole diameter (mm).

[0072] like Figure 4 As shown, in the freeze-thaw cycle treatment in S2, the sample is frozen at a temperature of -20°C for 12 hours; and then thawed at a temperature of 20°C for 12 hours.

[0073] like Figure 4 As shown, the number of freeze-thaw cycles in the freeze-thaw cycle treatment in S2 adopts a method of increasing the difference backward, and 0, 1, 3, 6 and 10 are selected.

[0074] When the freeze-thaw cycle treatment provided by the present invention is used, the number of freeze-thaw cycles adopts a method of increasing the difference backward, and 0, 1, 3, 6, and 10 are selected to ensure the accuracy of the test results.

[0075] like Figures 3 to 8 As shown, the tensile strength estimation model in S4 is expressed as follows:

[0076]

[0077] Where: S t is the tensile strength; W / C is the solid waste clay ratio; R c is the relative density; N FT is the number of freeze-thaw cycles; D s is the saturation; e is the mathematical constant 2.718; a1-a8 are model parameters.

[0078] When drawing the relationship curve,

[0079] W / C is set to: 1, 1.5, 2, 2.5;

[0080] The relative density is set as: 0.87, 0.9, 0.93, 0.96;

[0081] Saturation settings: 25%, 50%, 75%, 100%;

[0082] The number of freeze-thaw cycles was set as: 0, 1, 3, 6, and 10.

[0083] like Figure 9 As shown, the tensile strength estimation model in S4 adopts robustness verification, and the robustness verification draws a robustness verification scatter plot with the measured value of the tensile strength as the horizontal axis and the estimated value as the vertical axis.

[0084] The specific embodiment is shown in Table 1 below, and R is obtained by fitting. 2 =0.95, Table 2 shows the tensile test results of the working condition to verify the robustness of the model. Among them, the robustness verification scatter diagram is drawn with the measured value of tensile strength as the horizontal axis and the estimated value as the vertical axis. The results are as follows Figure 9 As shown, R 2 =0.93. Therefore, the new model has high accuracy and applicability and can be applied to the same type of materials and the tensile strength estimation of the same materials under other working conditions.

[0085] Table 1 Model parameters and fitting results of tensile strength prediction model

[0086] <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4]]> <![CDATA[a5]]> <![CDATA[a6]]> <![CDATA[a7]]> <![CDATA[a8]]> <![CDATA[R 2 ]]> 9.04 -2.15 8.97 0.17 -0.93 0.01 0.83 0.33 0.95

[0087] Table 2 Robustness verification conditions

[0088] factor Specific parameters W / C 1.25、1.75、2.25 <![CDATA[R c ]]> 0.88、0.91、0.94 <![CDATA[N FT ]]> 2、5、7 <![CDATA[D s / %]]> 35、65、85

[0089] Working principle: When estimating the tensile strength of solid waste materials, a new quantitative analysis indicator is first proposed for the physical grading state of solid waste - solid waste clay ratio; on this basis, according to the "Highway Geotechnical Test Code", the maximum dry density and optimal moisture content of solid waste under different W / C conditions are determined through heavy compaction tests; then, based on the compaction test results, samples with relative densities of 0.87, 0.9, 0.93, and 0.96 and saturations of 25%, 50%, 75%, and 100% are prepared. After the sample preparation is completed, the sample is placed in a high and low temperature alternating test machine for freeze-thaw cycle treatment. In order to ensure the stability of the internal moisture content of the sample during the freeze-thaw process, the sample is wrapped with plastic wrap until the freeze-thaw process is completed; after the freeze-thaw cycle treatment is completed, the electric stretching rod is connected to the threaded hole of the convex mold, and the stretching base is connected to the threaded hole of the concave mold; then, the electric stretching rod is controlled by a computer and a servo control switch to perform a tensile test, with a tensile rate of 0.5mm / min; according to the tensile test results, the solid waste is compared and analyzed. The tensile strength corresponding to different working conditions is established by comprehensively considering the solid waste clay ratio, relative density, saturation and number of freeze-thaw cycles; then, the test data of step S3 are fitted by the stepwise regression analysis method of SAS software to obtain the model parameters a1-a8. This fitting step is a conventional method and will not be repeated here; in addition, in order to verify the accuracy and applicability of the model established in this article, the robustness of the model is verified by using the tensile test results of different working conditions; by comprehensively considering the influence of factors such as gradation variables, density variables, humidity variables and environmental variables on its tensile strength, the tensile strength of solid waste materials under different conditions is quickly predicted; at the same time, the model has clear physical meaning and simple structure. It only needs to input the corresponding working conditions into the model to obtain the tensile strength value of the solid waste material under the coupling effect of the corresponding working conditions, which greatly reduces the test time and difficulty, provides obvious engineering convenience for units that do not have test conditions, and has high market promotion value.

[0090] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles, characterized by: The estimation method includes the following steps: S1: A new quantitative analysis index for the physical gradation of solid waste, namely the solid-waste-to-clay ratio, is proposed. Based on this, the maximum dry density and optimal moisture content of solid waste under different W / C conditions are determined through heavy compaction tests. S2: Based on the heavy compaction test results of step S1, samples with relative densities of 0.87, 0.9, 0.93, and 0.96 and saturations of 25%, 50%, 75%, and 100% are prepared; after sample preparation, the samples are placed in a high-low temperature alternating tester for freeze-thaw cycle treatment. To ensure the stability of the internal moisture content of the samples during the freeze-thaw process, the samples are wrapped with plastic wrap until the freeze-thaw process is completed; S3: After the freeze-thaw cycle treatment in step S2 is completed, the electric stretching rod is connected to the threaded hole of the convex mold, and the stretching base is connected to the threaded hole of the concave mold; then, the electric stretching rod is controlled by a computer and a servo control switch to perform a tensile test at a stretching rate of 0.5 mm / min; S4: Based on the tensile test results of step S3, the tensile strength of solid waste under different working conditions is compared and analyzed, and a tensile strength estimation model is established that comprehensively considers the solid waste clay ratio, relative density, saturation and number of freeze-thaw cycles; then, the test data of step S3 are fitted by the stepwise regression analysis method of SAS software to obtain the model parameters a1-a8.

2. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 1, characterized in that: The heavy compaction test in S1 includes the following steps: S101: Drying the solid waste and clay required for the compaction test for 24 hours; S102: Preset W / C material configuration; S103: The moisture content of the material is adjusted with a gradient difference of 2%, and the material is subjected to a 18-hour suffocation treatment to make the internal humidity uniform; S104: After the filling is completed, the mixed filler is compacted in three layers using a heavy compaction method, with each layer compacted 98 times; S105: The central portion of the molded sample is selected to measure the moisture content and dry density, thereby obtaining the maximum dry density and optimal moisture content of the solid waste under different W / C conditions.

3. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 2, characterized in that: The sample preparation in S2 comprises the following steps: S201: Using a hoop to connect the threaded hole of the inner concave mold and the threaded hole of the outer convex mold, thereby achieving connection and fixation at the mortise and tenon of the inner concave mold and the outer convex mold; S202: Place an outer pressure-bearing component on the upper side of the concave mold and the convex mold, and a pressure-bearing pad on the lower side, and place a disposable filter paper between the sample and the component and the pad to prevent damage to the sample when the component is removed; S203: The electric stretching rod and the loading plate are controlled by the computer and the servo control switch to vibrate the outer pressure-bearing component to prepare the sample. When the outer pressure-bearing component reaches a preset height, the loading is stopped.

4. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 3, characterized in that: The formula for the solid waste-to-clay ratio in S1 is: Where: W / C is the solid waste clay ratio; S max is the maximum screening size of solid waste (mm); k is the shape parameter of the physical gradation state; S f The aperture is f i The cumulative pass rate corresponding to the sieve holes (%); f i is the sieve hole diameter (mm).

5. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 4, characterized in that: In the freeze-thaw cycle treatment in S2, the sample is frozen at a temperature of -20°C for 12 hours and then thawed at a temperature of 20°C for 12 hours.

6. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 5, characterized in that: The number of freeze-thaw cycles in the freeze-thaw cycle treatment in S2 is selected as 0, 1, 3, 6 and 10 by increasing the difference backward.

7. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 6, characterized in that: The tensile strength prediction model in S4 is expressed as follows: Where: S t is the tensile strength; W / C is the solid waste clay ratio; R c is the relative density; N FT is the number of freeze-thaw cycles; D s is the saturation; e is the mathematical constant 2.718; a1-a8 are model parameters.

8. The method for estimating the tensile strength of roadbed solid waste modified soil considering freeze-thaw cycles according to claim 7, characterized in that: The tensile strength estimation model in S4 adopts robustness verification, and the robustness verification draws a robustness verification scatter plot with the actual tensile strength value as the horizontal axis and the estimated value as the vertical axis.

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