Method for predicting internal friction angle of sandy pebble soil

Abstract

The invention discloses a method for predicting an internal friction angle of sandy pebble soil, which belongs to the technical field of geotechnical engineering, and comprises the following steps: a, obtaining the weight of a soil body, and screening to obtain the gradation of the soil body; b, calculating the porosity of the soil body; c, obtaining an original soil stress-strain curve; d, carrying out basic data calibration on the stress-strain curve of the original soil body; e, obtaining a quadratic function relationship between the particle weight and the internal friction angle; f, obtaining a linear function relationship between the soil porosity and the internal friction angle; g, values corresponding to the internal friction angle under different curvature coefficient or non-uniform coefficient changes are calculated for curve fitting, and a linear function relation between the curvature coefficient and the internal friction angle and a linear function relation between the non-uniform coefficient and the internal friction angle are obtained respectively; and h, carrying out multi-parameter fusion to obtain a relational expression about the fused physical property parameters and the internal friction angle. The method can be used for estimating the internal friction angle of the sandy pebble soil, and is simple and convenient to operate, high in accuracy and good in applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering, and in particular to a method for predicting the internal friction angle of sandy pebble soil. Background Art

[0002] Sandy pebble soil, a common geological material left over from glacial moraine deposits in the Sichuan-Tibet region, has extensive applications in geotechnical engineering. Its mechanical properties, particularly the internal friction angle, significantly influence its stability and bearing capacity. However, the internal friction angle of sandy pebble soil is affected by multiple physical parameters, making accurate prediction complex.

[0003] At present, there are two main methods for studying the internal friction angle of sandy pebble soil under the influence of multiple physical parameters at home and abroad: One approach, based on extensive geotechnical testing, examines the influence of multiple soil physical parameters, including specific gravity, density, particle size, and graded stone content, on the internal friction angle. Most of these methods are based on small- to medium-scale indoor triaxial scale tests, with the maximum particle size of the specimens ranging from 5 to 20 mm. This approach does not represent the actual conditions for larger pebble soils, and the resulting internal friction angles are often biased upwards.

[0004] Second, based on the PFC numerical simulation test, a large number of geotechnical tests were obtained based on clay, silt and sand samples, without considering the undulating shape of the block surface. In addition, there is a lack of public research cases and relevant data on the research data of the unique moraine pebble soil samples in the high-relief areas of the eastern Qinghai-Tibet Plateau, resulting in distortion of regional geotechnical parameters.

[0005] A Chinese patent document with publication number CN104963328A, published on October 7, 2015, discloses a method for determining the internal friction angle of coarse-grained soil at a great burial depth. The method includes the following steps: a. collecting in-situ mechanical test values; b. performing statistical correlation analysis on the soil dry density, average particle size, and corresponding internal friction angle; c. establishing a relationship for the internal friction angle; d. obtaining the soil dry density and average particle size at a great burial depth; and e. substituting the soil dry density and average particle size into the relationship to obtain the internal friction angle.

[0006] The method disclosed in this patent document for determining the internal friction angle of coarse-grained soil at great depths effectively uses an empirical formula to determine the internal friction angle of coarse-grained soil at different locations. However, the internal friction angles obtained under different test methods and conditions vary significantly. For example, the internal friction angles obtained by this method based on direct shear tests are less accurate than those obtained under triaxial tests. Furthermore, under the same operating conditions and test conditions, the internal friction angles obtained from large triaxial tests are smaller than those obtained from small triaxial tests, resulting in distorted statistical results.

[0007] A Chinese patent document with publication number CN 116386780A and publication date July 4, 2023, discloses a method for predicting the internal friction angle of a binary particle mixture, which is characterized by comprising: The fine particle content at the critical point of shear strength index is calculated based on the particle size ratio of coarse particles to fine particles; The critical internal friction angle corresponding to the fine particle content at the critical point of the shear strength index is calculated based on the particle size ratio and shape parameters of the particles. According to the fine particle content at the critical point of shear strength index and its corresponding critical internal friction angle, a broken line model of the internal friction angle of binary particle mixtures varying with particle size distribution was constructed. The internal friction angle of binary granular soil under arbitrary particle size distribution is estimated by the broken line model.

[0008] The method for predicting the internal friction angle of a binary particle mixture disclosed in this patent document can estimate the internal friction angle of a binary particle mixture under any fine particle content condition. However, it requires many basic calculation parameters, the process is complicated, the actual operability on site is not high, and the applicability is poor. Summary of the Invention

[0009] In order to overcome the above-mentioned defects of the prior art, the present invention provides a method for predicting the internal friction angle of sandy pebble soil. The present invention can estimate the internal friction angle of sandy pebble soil, and is simple to operate, highly accurate and has good applicability.

[0010] The present invention is achieved through the following technical solutions: A method for predicting the internal friction angle of sandy pebble soil is characterized by comprising the following steps: a. Conduct bulk density tests on moraine sandy pebble soil at different burial depths to obtain soil weight and obtain soil gradation through screening; b. Measure the volume of the sampled soil, convert the volume using the graduated cylinder method to obtain the particle density, obtain the dry mass of the soil using the drying method, and calculate the soil porosity; c. Conduct a large-scale triaxial test on the sampled soil and select the consolidation condition to obtain the original soil stress-strain curve; d. Calibrate the basic data of the original soil stress-strain curve; e. Calculate the values ​​of the internal friction angle under different changes in particle weight and perform corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the values ​​of the internal friction angle under different soil porosity changes and perform corresponding curve fitting to obtain the linear function relationship between soil porosity and internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Based on the relationship between the single variable and the internal friction angle obtained in step eg, perform multi-parameter fusion to obtain the relationship between the fused physical property parameters and the internal friction angle.

[0011] In step a, the bulk density test refers to the experiment conducted by the water filling method, and the test pit volume is greater than 1m 3 .

[0012] In step b, the soil porosity is calculated using formula 1; Formula 1 in, is the soil porosity, is the drying mass of the soil, V is the volume of the sampled soil, For particle weight.

[0013] In step c, the height of the sampled soil is 600 mm and the diameter is 300 mm.

[0014] In the step d, basic data calibration refers to calibration by three-dimensional particle dynamics software.

[0015] In step e, the values ​​of the internal friction angle corresponding to the changes in particle weight are calculated using three-dimensional particle dynamics software, and the quadratic function relationship between particle weight and internal friction angle is expressed by formula 2; Formula 2 in, is the internal friction angle, For particle weight.

[0016] In step f, the values ​​of the internal friction angle corresponding to different soil porosity changes are calculated using three-dimensional particle dynamics software, and the linear function relationship between the soil porosity and the internal friction angle is expressed by formula 3; Formula 3 in, is the internal friction angle, is the soil porosity.

[0017] In step g, the values ​​of the internal friction angle corresponding to different curvature coefficients or uneven coefficients are calculated using three-dimensional particle dynamics software. The linear function relationship between the curvature coefficient and the internal friction angle is expressed by formula 4, and the linear function relationship between the uneven coefficient and the internal friction angle is expressed by formula 5. Formula 4 Formula 5 in, is the internal friction angle, is the non-uniformity coefficient, is the curvature coefficient.

[0018] In the step h, the fused physical parameters include the unevenness coefficient and curvature coefficient, the unevenness coefficient and particle density, the unevenness coefficient and soil porosity, the curvature coefficient and particle density, the curvature coefficient and soil porosity, and the particle density and soil porosity.

[0019] The basic principles of the present invention are as follows: The internal friction angle of sandy gravel soils deposited on moraines is significantly influenced by the variability of the soil's particle structure. The value of the internal friction angle is closely correlated with several key physical properties. Current research suggests that variations in particle size distribution are the most influential factor, followed closely by other factors such as soil porosity and particle density, with similar or minimal influence.

[0020] To gain a deeper understanding of the relationship between these parameters and the internal friction angle, extensive preliminary field testing was conducted. These tests successfully determined the variations in basic soil properties, such as particle density, porosity, heterogeneity coefficient, and curvature coefficient. Further investigation was conducted using triaxial tests on coarse-grained soils to explore the joint functional relationship between variations in individual physical parameters and the internal friction angle.

[0021] On this basis, we strictly adhered to the functional power relationship between a single physical property parameter and the internal friction angle, and combined multiple physical property factors to vary. In this way, we obtained the value of the internal friction angle under the conditions of multi-factor variation, and constructed the corresponding functional relationship based on this.

[0022] The beneficial effects of the present invention are mainly manifested in the following aspects: 1. The present invention comprises the following steps: a. conducting a large bulk density test of sandy pebble soil of moraine under different burial depths to obtain soil weight, and obtaining soil gradation by screening; b. measuring the volume of the sampled soil, obtaining particle weight by volume conversion using the measuring cylinder method, obtaining soil drying mass by the drying method, and calculating soil porosity; c. conducting a large triaxial test on the sampled soil, selecting the consolidation condition to obtain the original soil stress-strain curve; d. calibrating the basic data of the original soil stress-strain curve; e. calculating the value corresponding to the internal friction angle under different particle weight changes, and performing corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. calculating the porosity of different soils. g. Calculate the values ​​of the internal friction angle under different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Perform multi-parameter fusion based on the relationship between the single variable and the internal friction angle obtained in step e.g. to obtain the relationship between the fused physical parameters and the internal friction angle. Compared with the existing technology, the internal friction angle of sandy pebble soil can be estimated with simple operation, high accuracy and good applicability.

[0023] 2. Based on previous on-site actual tests, the present invention effectively eliminates hypothetical extreme parameter settings and adopts large triaxial tests on coarse-grained soil to obtain the internal friction angle value, effectively solving the problem of obtaining a large internal friction angle when the particle size is too small.

[0024] 3. The present invention establishes a more accurate functional relationship by comprehensively considering the influence of multiple physical parameters on the internal friction angle of sandy pebble soil, thereby being able to more accurately predict the internal friction angle and providing reliable data support for geotechnical engineering design.

[0025] 4. The present invention is not only applicable to the sandy pebble soil left by glacial moraine that is common in the Sichuan-Tibet region, but can also be extended to soils under other similar geological conditions, and has wide applicability.

[0026] 5. Compared with the prior art which relies on a large number of geotechnical tests to obtain internal friction angle data, which is time-consuming, labor-intensive, and costly, the present invention combines numerical simulation with field tests, reduces the number of tests and reduces costs, while ensuring the accuracy of the prediction results and improving the test efficiency.

[0027] 6. The overall operation process of the present invention is relatively simple and clear, easy to implement on site, and conducive to ensuring the accuracy and consistency of the prediction results. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments: Figure 1 It is a flowchart of the present invention. DETAILED DESCRIPTION

[0029] Example 1 See also Figure 1 A method for predicting the internal friction angle of sandy pebble soil comprises the following steps: a. Conduct bulk density tests on moraine sandy pebble soil at different burial depths to obtain soil weight and obtain soil gradation through screening; b. Measure the volume of the sampled soil, convert the volume using the graduated cylinder method to obtain the particle density, obtain the dry mass of the soil using the drying method, and calculate the soil porosity; c. Conduct a large-scale triaxial test on the sampled soil and select the consolidation condition to obtain the original soil stress-strain curve; d. Calibrate the basic data of the original soil stress-strain curve; e. Calculate the values ​​of the internal friction angle under different changes in particle weight and perform corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the values ​​of the internal friction angle under different soil porosity changes and perform corresponding curve fitting to obtain the linear function relationship between soil porosity and internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Based on the relationship between the single variable and the internal friction angle obtained in step eg, perform multi-parameter fusion to obtain the relationship between the fused physical property parameters and the internal friction angle.

[0030] This embodiment is the most basic implementation method, a. Carry out large-scale bulk density tests on sandy pebble soil of moraine under different burial depth conditions, obtain soil weight, and obtain soil gradation by screening; b. Measure the volume of sampled soil, obtain particle weight by volume conversion using the measuring cylinder method, obtain soil drying mass by the drying method, and calculate soil porosity; c. Carry out large-scale triaxial tests on sampled soil, select consolidation conditions to obtain the original soil stress-strain curve; d. Calibrate basic data of the original soil stress-strain curve; e. Calculate the value corresponding to the internal friction angle under different particle weight changes, perform corresponding curve fitting, and obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the non- g. Calculate the values ​​of the internal friction angle corresponding to the soil porosity change and perform corresponding curve fitting to obtain a linear function relationship between the soil porosity and the internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to the different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain a linear function relationship between the curvature coefficient and the internal friction angle and a linear function relationship between the unevenness coefficient and the internal friction angle, respectively; h. Perform multi-parameter fusion based on the relationship between the single variable and the internal friction angle obtained in step e.g. to obtain a relationship between the fused physical parameters and the internal friction angle. Compared with the existing technology, the internal friction angle of sandy pebble soil can be estimated, and the operation is simple, the accuracy is high, and the applicability is good.

[0031] Example 2 See also Figure 1 A method for predicting the internal friction angle of sandy pebble soil comprises the following steps: a. Conduct bulk density tests on moraine sandy pebble soil at different burial depths to obtain soil weight and obtain soil gradation through screening; b. Measure the volume of the sampled soil, convert the volume using the graduated cylinder method to obtain the particle density, obtain the dry mass of the soil using the drying method, and calculate the soil porosity; c. Conduct a large-scale triaxial test on the sampled soil and select the consolidation condition to obtain the original soil stress-strain curve; d. Calibrate the basic data of the original soil stress-strain curve; e. Calculate the values ​​of the internal friction angle under different changes in particle weight and perform corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the values ​​of the internal friction angle under different soil porosity changes and perform corresponding curve fitting to obtain the linear function relationship between soil porosity and internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Based on the relationship between the single variable and the internal friction angle obtained in step eg, perform multi-parameter fusion to obtain the relationship between the fused physical property parameters and the internal friction angle.

[0032] In step a, the bulk density test refers to the experiment conducted by the water filling method, and the test pit volume is greater than 1m 3 .

[0033] In step b, the soil porosity is calculated using formula 1; Formula 1 in, is the soil porosity, is the drying mass of the soil, V is the volume of the sampled soil, For particle weight.

[0034] This embodiment is a preferred implementation method. Based on previous actual field tests, it effectively eliminates hypothetical extreme parameter settings and adopts a large triaxial test on coarse-grained soil to obtain the internal friction angle value, effectively solving the problem of obtaining a large internal friction angle when the particle size is too small.

[0035] Example 3 See also Figure 1 A method for predicting the internal friction angle of sandy pebble soil comprises the following steps: a. Conduct bulk density tests on moraine sandy pebble soil at different burial depths to obtain soil weight and obtain soil gradation through screening; b. Measure the volume of the sampled soil, convert the volume using the graduated cylinder method to obtain the particle density, obtain the dry mass of the soil using the drying method, and calculate the soil porosity; c. Conduct a large-scale triaxial test on the sampled soil and select the consolidation condition to obtain the original soil stress-strain curve; d. Calibrate the basic data of the original soil stress-strain curve; e. Calculate the values ​​of the internal friction angle under different changes in particle weight and perform corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the values ​​of the internal friction angle under different soil porosity changes and perform corresponding curve fitting to obtain the linear function relationship between soil porosity and internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Based on the relationship between the single variable and the internal friction angle obtained in step eg, perform multi-parameter fusion to obtain the relationship between the fused physical property parameters and the internal friction angle.

[0036] In step a, the bulk density test refers to the experiment conducted by the water filling method, and the test pit volume is greater than 1m 3 .

[0037] In step b, the soil porosity is calculated using formula 1; Formula 1 in, is the soil porosity, is the drying mass of the soil, V is the volume of the sampled soil, For particle weight.

[0038] In step c, the height of the sampled soil is 600 mm and the diameter is 300 mm.

[0039] In the step d, basic data calibration refers to calibration by three-dimensional particle dynamics software.

[0040] In step e, the values ​​of the internal friction angle corresponding to the changes in particle weight are calculated using three-dimensional particle dynamics software, and the quadratic function relationship between particle weight and internal friction angle is expressed by formula 2; Formula 2 in, is the internal friction angle, For particle weight.

[0041] In step f, the values ​​of the internal friction angle corresponding to different soil porosity changes are calculated using three-dimensional particle dynamics software, and the linear function relationship between the soil porosity and the internal friction angle is expressed by formula 3; Formula 3 in, is the internal friction angle, is the soil porosity.

[0042] This embodiment is another preferred implementation method. By comprehensively considering the influence of multiple physical parameters on the internal friction angle of sandy gravel soil, a more accurate functional relationship is established, which can more accurately predict the internal friction angle and provide reliable data support for geotechnical engineering design.

[0043] Example 4 See also Figure 1 A method for predicting the internal friction angle of sandy pebble soil comprises the following steps: a. Conduct bulk density tests on moraine sandy pebble soil at different burial depths to obtain soil weight and obtain soil gradation through screening; b. Measure the volume of the sampled soil, convert the volume using the graduated cylinder method to obtain the particle density, obtain the dry mass of the soil using the drying method, and calculate the soil porosity; c. Conduct a large-scale triaxial test on the sampled soil and select the consolidation condition to obtain the original soil stress-strain curve; d. Calibrate the basic data of the original soil stress-strain curve; e. Calculate the values ​​of the internal friction angle under different changes in particle weight and perform corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the values ​​of the internal friction angle under different soil porosity changes and perform corresponding curve fitting to obtain the linear function relationship between soil porosity and internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Based on the relationship between the single variable and the internal friction angle obtained in step eg, perform multi-parameter fusion to obtain the relationship between the fused physical property parameters and the internal friction angle.

[0044] In step a, the bulk density test refers to the experiment conducted by the water filling method, and the test pit volume is greater than 1m 3 .

[0045] In step b, the soil porosity is calculated using formula 1; Formula 1 in, is the soil porosity, is the drying mass of the soil, V is the volume of the sampled soil, For particle weight.

[0046] In step c, the height of the sampled soil is 600 mm and the diameter is 300 mm.

[0047] In the step d, basic data calibration refers to calibration by three-dimensional particle dynamics software.

[0048] In step e, the values ​​of the internal friction angle corresponding to the changes in particle weight are calculated using three-dimensional particle dynamics software, and the quadratic function relationship between particle weight and internal friction angle is expressed by formula 2; Formula 2 in, is the internal friction angle, For particle weight.

[0049] In step f, the values ​​of the internal friction angle corresponding to different soil porosity changes are calculated using three-dimensional particle dynamics software, and the linear function relationship between the soil porosity and the internal friction angle is expressed by formula 3; Formula 3 in, is the internal friction angle, is the soil porosity.

[0050] In step g, the values ​​of the internal friction angle corresponding to different curvature coefficients or uneven coefficients are calculated using three-dimensional particle dynamics software. The linear function relationship between the curvature coefficient and the internal friction angle is expressed by formula 4, and the linear function relationship between the uneven coefficient and the internal friction angle is expressed by formula 5. Formula 4 Formula 5 in, is the internal friction angle, is the non-uniformity coefficient, is the curvature coefficient.

[0051] In the step h, the fused physical parameters include the unevenness coefficient and curvature coefficient, the unevenness coefficient and particle density, the unevenness coefficient and soil porosity, the curvature coefficient and particle density, the curvature coefficient and soil porosity, and the particle density and soil porosity.

[0052] This embodiment is the best implementation method and is not only applicable to the sandy gravel soil left by glacial moraine that is common in the Sichuan-Tibet region, but can also be extended to soils under other similar geological conditions, and has wide applicability.

[0053] Compared with the existing technology that relies on a large number of geotechnical tests to obtain internal friction angle data, which is time-consuming, labor-intensive and costly, the combination of numerical simulation and field tests reduces the number of tests and reduces costs, while ensuring the accuracy of the prediction results and improving test efficiency.

[0054] The overall operation process is relatively simple and clear, easy to implement on site, and conducive to ensuring the accuracy and consistency of the prediction results.

[0055] The present invention will be described below with specific examples: For the common sandy gravel soil in the site, the soil weight distribution is 21-25KN / m by using the bulk density test. 3 The volume of the sampled soil was measured using the water filling method, the particle density was obtained by volume conversion using the graduated cylinder method, and the soil moisture content was obtained by the drying method. The soil porosity was obtained using Equation 1. The site curvature coefficient obtained from the coarse-grained soil screening experiment ranged from 0.53 to 2.12, with the maximum probability occurring at 1.18. The unevenness coefficient ranged from 30.05 to 72.82, with the maximum probability occurring at 45.56.

[0056] The coarse-grained soil triaxial test was carried out on the remolded soil sample. The sample size was H = 600 mm, the sample diameter was D = 300 mm, and the test condition was consolidation and drainage. The stress-strain curve of the original soil was obtained.

[0057] With reference to the original soil stress-strain curve, the existing three-dimensional particle dynamics software was used to calibrate the data and obtain the calibrated basic parameters, as shown in Table 1. The average correlation coefficient between the stress-strain curve obtained based on the calibrated basic parameters and the original soil stress-strain curve was greater than 80%. Subsequently, the particle density, porosity, and gradation conditions were changed to keep the calibrated basic parameters unchanged.

[0058] Table 1 Using three-dimensional particle dynamics software, under low confining pressures of 100 kPa, 200 kPa, and 300 kPa and consolidation conditions, the particle density was continuously changed to obtain stress-strain curves. The internal friction angle of the sample was then obtained based on the stress Mohr circle, and the relationship between the two was obtained: Using three-dimensional particle dynamics software, under low confining pressures of 100 kPa, 200 kPa, and 300 kPa and consolidation conditions, the porosity was continuously changed to obtain stress-strain curves. The internal friction angle of the sample was then obtained based on the stress Mohr circle, and the relationship between the two was obtained: Using three-dimensional particle dynamics software, under low confining pressures of 100 kPa, 200 kPa, and 300 kPa and consolidation conditions, the porosity was continuously changed to obtain stress-strain curves. The internal friction angle of the sample was then obtained based on the stress Mohr circle, and the relationship between the two was obtained: Keeping the power relationship between each basic physical property parameter and the internal friction angle unchanged, multiple physical property factors are integrated and jointly changed to obtain the value of the internal friction angle, and the corresponding functional relationship is constructed based on it, see Table 2.

[0059] Table 2

Claims

1. A method for predicting the internal friction angle of sandy pebble soil, characterized in that: The following steps are involved: a. Conduct bulk density tests on moraine sandy pebble soil at different burial depths to obtain soil weight and obtain soil gradation through screening; b. Measure the volume of the sampled soil, convert the volume using the graduated cylinder method to obtain the particle density, obtain the dry mass of the soil using the drying method, and calculate the soil porosity; c. Conduct a large-scale triaxial test on the sampled soil and select the consolidation condition to obtain the original soil stress-strain curve; d. Calibrate the basic data of the original soil stress-strain curve; e. Calculate the values ​​of the internal friction angle under different changes in particle weight and perform corresponding curve fitting to obtain the quadratic function relationship between particle weight and internal friction angle; f. Calculate the values ​​of the internal friction angle under different soil porosity changes and perform corresponding curve fitting to obtain the linear function relationship between soil porosity and internal friction angle; g. Calculate the values ​​of the internal friction angle corresponding to different curvature coefficients or unevenness coefficients and perform corresponding curve fitting to obtain the linear function relationship between the curvature coefficient and the internal friction angle and the linear function relationship between the unevenness coefficient and the internal friction angle respectively; h. Based on the relationship between the single variable and the internal friction angle obtained in step eg, perform multi-parameter fusion to obtain the relationship between the fused physical property parameters and the internal friction angle.

2. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In step a, the bulk density test refers to the experiment conducted by the water filling method, and the test pit volume is greater than 1m 3 .

3. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In step b, the soil porosity is calculated using formula 1; Formula 1 in, is the soil porosity, is the drying mass of the soil, V is the volume of the sampled soil, For particle weight.

4. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In step c, the height of the sampled soil is 600 mm and the diameter is 300 mm.

5. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In the step d, basic data calibration refers to calibration by three-dimensional particle dynamics software.

6. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In step e, the values ​​of the internal friction angle corresponding to the changes in particle weight are calculated using three-dimensional particle dynamics software, and the quadratic function relationship between particle weight and internal friction angle is expressed by formula 2; Formula 2 in, is the internal friction angle, For particle weight.

7. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In step f, the values ​​of the internal friction angle corresponding to different soil porosity changes are calculated using three-dimensional particle dynamics software, and the linear function relationship between the soil porosity and the internal friction angle is expressed by formula 3; Formula 3 in, is the internal friction angle, is the soil porosity.

8. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In step g, the values ​​of the internal friction angle corresponding to different curvature coefficients or uneven coefficients are calculated using three-dimensional particle dynamics software. The linear function relationship between the curvature coefficient and the internal friction angle is expressed by formula 4, and the linear function relationship between the uneven coefficient and the internal friction angle is expressed by formula 5. Formula 4 Formula 5 in, is the internal friction angle, is the non-uniformity coefficient, is the curvature coefficient.

9. The method for predicting the internal friction angle of sandy pebble soil according to claim 1, wherein: In the step h, the fused physical parameters include the unevenness coefficient and curvature coefficient, the unevenness coefficient and particle density, the unevenness coefficient and soil porosity, the curvature coefficient and particle density, the curvature coefficient and soil porosity, and the particle density and soil porosity.

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