Macro–Micro Correlation Mechanism Between Structural Potential and Mechanical Strength in Collapsible Loess
Abstract
1. Introduction
2. Materials and Methods
2.1. Test Materials
2.2. Sample Preparation
2.3. Test Method
2.3.1. Consolidation Test
2.3.2. Particle Analysis Test
2.3.3. MIP Test
2.3.4. Verification of Test Procedures
3. Results and Analysis
3.1. Consolidation Test Analysis
3.2. Particle Analysis Test Analysis
3.3. MIP Assay Analysis
4. Grain Fraction Potential, Pore Potential, and Connection Potential of Loess
4.1. Determination of the Grain Fraction Potential of Loess
4.1.1. Study on Fractal Dimension Characteristics of Loess Particles
4.1.2. Research on the Method of Determining the Particle Size Potential of Loess
- (1)
- The particle size of the sample was characterized using either experimental techniques or a laser particle size analyzer, and the resulting distribution curve was illustrated. The horizontal coordinate was the particle size r, and the vertical coordinate was the proportion of the cumulative quantity of the particle η, where the unit of r was mm.
- (2)
- The particle size potential of soil can be represented by the distribution characteristics of the cumulative number of particles (1 − η) greater than or equal to a specific particle size (r). Specifically, it is reflected by the morphological characteristics of the r − (1 − η) curve. It is worth noting that there is a power function correspondence between r and (1 − η), as shown in Equation (2):
- (3)
- The fractal dimension of particle size D was calculated. The horizontal coordinate of the double-logarithmic coordinate system was defined as the particle size r. The vertical coordinate was the proportion of particles larger than the particle size to the total particle number (1 − η). The fractal dimension D is calculated by fitting the slope of the line with a one-time function. Equation (2) is converted to Equation (3), and k is the constant term after the logarithm of Equation (2):
- (4)
- The granularity fractal dimension D is classified according to Table 4.
4.2. Determination of the Pore Potential of Loess
- (1)
- A mercury injection instrument tests the pore distribution of different soils. The horizontal coordinate is equivalent to pore size R, and the vertical coordinate is the proportion of pore size R in the total pore volume and the pore size distribution.
- (2)
- A length of 8 μm is identified as the boundary between overhead pores and intergranular pores. Then, the pore potential of the soil can be characterized by the large and medium pore ratios of the soil, and the pores of different equivalent pore sizes can be summed up or read directly by the instrument. The proportion of large and medium pore ratios can be expressed by Equation (4) as follows:
- (1)
- Equation (4) is used to compute the percentage of large and medium pore volumes, denoted as n, and the computed outcomes are presented in Table 5.
- (2)
- Table 6 serves as the basis for categorizing the percentage of large and medium pore volumes, denoted as n.
4.3. Determination of the Connection Potential of Loess
4.4. Comprehensive Determination of Structural Potential of Loess
5. Judgment Method Test
6. Conclusions
- (1)
- Based on the experimental results of reshaped loess particle analysis, it was found that the interval percentage curves of reshaped loess under different water content and pressure conditions all reached the peak point at the median particle size, with a “double peak” situation. The proportion of powder particles (2–50 μm) was the largest, the proportion of clay particles (<2 μm) was the second, and the proportion of sand particles (>50 μm) was the least. When the external pressure is constant, the change in water content has no noticeable effect on the particle distribution in the soil.
- (2)
- Based on Xie’s definition of structural quantitative index-comprehensive structural potential theory, soil structural potential is subdivided into three kinds of meso-structural potential: grain size, pore, and connection potential. The correlation between soil structural potential, comprehensive structural potential, and other macroscopic mechanical indexes was studied through the fractal dimension value of particle size, the ratio of large and medium pores, and the soluble salt content of soil particles.
- (3)
- A new method for evaluating the structural potential strength of loess based on macro and micro correlation was proposed. The method has the characteristics of macro and micro correlation, simplicity, high operability, and high accuracy. Under natural conditions, the reshaping of the loess in the test area has a high grain size potential, high pore potential, and medium connection potential. The soil samples show good gradation, high compressibility, strong collapsibility, and moderate soluble salt content.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
- Weng, X.; Sun, Y.; Zhang, Y.; Niu, H.; Liu, X.; Dong, Y. Physical modeling of wetting-induced collapse of shield tunneling in loess strata. Tunn. Undergr. Space Technol. 2019, 90, 208–219. [Google Scholar] [CrossRef]
- Chen, Y.; Zhang, R.; Zi, J.; Han, J.; Liu, K. Evaluation of the treatment variables on the shear strength of loess treated by microbial induced carbonate precipitation. J. Mount. Sci. 2025, 22, 1075–1086. [Google Scholar] [CrossRef]
- Tang, K.; Qiu, J.; Lai, J.; Xue, F.; Wang, Z.; Li, X. Experimental investigation on deformation-failure mechanisms of a shallow-bias large-section loess tunnel induced by rainfall. Tunn. Undergr. Space Technol. 2025, 157, 106253. [Google Scholar] [CrossRef]
- Chen, Y.; Dong, M.; Cheng, C.; Han, J.; Zhao, Y.; Jia, P. Experimental and analytical study on the bearing capacity of caisson foundation subjected to V-H combined load. Mar. Georesour. Geotechnol. 2025, 1–13. [Google Scholar] [CrossRef]
- Ma, L.; Zhang, L.; Hou, X.; Guo, S.; Qi, S. Three-Dimensional Microstructure and Structural Representative Volume Element of the Intact and Remolded Loess. Appl. Sci. 2025, 15, 3120. [Google Scholar] [CrossRef]
- Wu, Z.; Xu, S.; Chen, D.; Zhao, D.; Zhang, D. An experimental study of the influence of structural parameters on dynamic characteristics of loess. Soil Dyn. Earthq. Eng. 2020, 132, 106067. [Google Scholar] [CrossRef]
- Lv, Q.; Sui, W.; Zhang, Z.; Gulmira, A. Macro–micro correlation analysis on the loess from Ili River Valley subjected to freeze–thaw cycles. Sci. Rep. 2024, 14, 19322. [Google Scholar] [CrossRef]
- Jiang, M.; Zhang, H.; Sun, R. Investigating the shear behaviors of unsaturated structured loess in direct shear test by the discrete element method. Jpn. Geotech. Soc. Spec. Publ. 2020, 8, 294–298. [Google Scholar] [CrossRef]
- Asadoullahtabar, S.R.; Asgari, A.; Tabari, M.M.R. Assessment, identifying, and presenting a plan for the stabilization of loessic soils exposed to scouring in the path of gas pipelines, case study: Maraveh-Tappeh city. Eng. Geol. 2024, 342, 107747. [Google Scholar] [CrossRef]
- Li, X.A.; Sun, J.; Ren, H.; Lu, T.; Ren, Y.; Pang, T. The effect of particle size distribution and shape on the microscopic behaviour of loess via the DEM. Environ. Earth Sci. 2022, 81, 290. [Google Scholar] [CrossRef]
- Wei, Y.Z.; Yao, Z.H.; Chong, X.L.; Zhang, J.H.; Zhang, J. Microstructure of unsaturated loess and its influence on strength characteristics. Sci. Rep. 2022, 12, 1502. [Google Scholar] [CrossRef] [PubMed]
- Zheng, H.; Li, X.A.; Deng, Y.H.; Hao, Z.T.; Wen, F. Study on the influence of initial state on loess erosion characteristics and microscopic mechanism. Sustainability 2023, 15, 4676. [Google Scholar] [CrossRef]
- Pan, L.; Zhu, J.G.; Zhang, Y.F. Evaluation of structural strength and parameters of collapsible loess. Int. J. Geomech. 2021, 21, 04021066. [Google Scholar] [CrossRef]
- Miao, F.; Zhao, F.; Wu, Y.; Li, L.; Ding, Y.; Meng, J. Macro and micro connections for slip zone soils of landslide under wetting–drying cycles in the Three Gorges Reservoir area. Landslides 2024, 21, 737–752. [Google Scholar] [CrossRef]
- Li, P.; Xie, W.; Pak, R.Y.; Vanapalli, S.K. Microstructural evolution of loess soils from the Loess Plateau of China. Catena 2019, 173, 276–288. [Google Scholar] [CrossRef]
- Li, X.A.; Li, L.; Song, Y.; Hong, B.; Wang, L.; Sun, J. Characterization of the mechanisms underlying loess collapsibility for land-creation project in Shaanxi Province, China—A study from a micro perspective. Eng. Geol. 2019, 249, 77–88. [Google Scholar] [CrossRef]
- Li, Y.; Zhang, T.; Zhang, Y.; Xu, Q. Geometrical appearance and spatial arrangement of structural blocks of the Malan loess in NW China: Implications for the formation of loess columns. J. Asian Earth Sci. 2018, 158, 18–28. [Google Scholar] [CrossRef]
- Ng, C.W.W.; Sadeghi, H.; Hossen, S.B.; Chiu, C.F.; Alonso, E.E.; Baghbanrezvan, S. Water retention and volumetric characteristics of intact and re-compacted loess. Can. Geotech. J. 2016, 53, 1258–1269. [Google Scholar] [CrossRef]
- Liu, Z.; Liu, F.; Ma, F.; Wang, M.; Bai, X.; Zheng, Y.; Zhang, G. Collapsibility, composition, and microstructure of loess in China. Can. Geotech. J. 2016, 53, 673–686. [Google Scholar] [CrossRef]
- Li, Y.; Zhang, W.; Aydin, A.; Deng, X. Formation of calcareous nodules in loess–paleosol sequences: Reviews of existing models with a proposed new “per evapotranspiration model”. J. Asian Earth Sci. 2018, 154, 8–16. [Google Scholar] [CrossRef]
- Chen, H.; Jiang, Y.; Niu, C.; Leng, G.; Tian, G. Dynamic characteristics of saturated loess under different confining pressures: A microscopic analysis. Bull. Eng. Geol. Environ. 2019, 78, 931–944. [Google Scholar] [CrossRef]
- Chen, H.; Jiang, Y.; Gao, Y.; Yuan, X. Structural characteristics and its influencing factors of typical loess. Bull. Eng. Geol. Environ. 2019, 78, 4893–4905. [Google Scholar] [CrossRef]
- Xie, D.Y.; Qi, J.L.; Zhang, Z.Z. A constitutive law considering soil structural properties. China Civ. Eng. J. 2000, 33, 35–41. [Google Scholar]
- Xie, D.Y.; Qi, J.L.; Zhu, Y.L. Soil structure parameter and its relations to deformation and strength. J. Hydraul. Eng. 1999, 30, 1–6. [Google Scholar]
- Chen, C.L.; Shao, S.J.; Deng, G.H. Relationship between soil structural parameters and strength and its application in slope stability analysis. Journal of Central South University. Sci. Technol. 2010, 41, 328–334. [Google Scholar]
- Luo, F.; Zhang, G.; Yao, Y. Macro-micro tests of cohesive soil under varied normal and shear stresses subjected to drying-wetting cycles. J. Rock Mech. Geotech. Eng. 2024, in press. [Google Scholar] [CrossRef]
- Li, Y.; Wang, Y.; Aydin, A. Loess structure: Evolution and a scale-based classification. Earth Sci. Rev. 2024, 249, 104665. [Google Scholar] [CrossRef]
- ASTM. Annual Book of ASTM Standards; ASTM International, American Society for Testing Materials: West Conshohocken, PA, USA, 2009. [Google Scholar]
- GB/T 50123-2019; Standard for Geotechnical Testing Method. Construction Ministry of PRC: Beijing, China, 2019.
- Wu, J.; Yang, N.; Li, P.; Yang, C. Influence of moisture content and dry density on the compressibility of disturbed loess: A case study in Yan’an City, China. Sustainability 2023, 15, 6212. [Google Scholar] [CrossRef]
- Wang, J.D.; Li, P.; Ma, Y.; Vanapalli, S.K. Evolution of pore-size distribution of intact loess and remolded loess due to consolidation. J. Soils Sediments 2019, 19, 1226–1238. [Google Scholar] [CrossRef]
- Wang, H.; Ni, W.; Liu, H.; Huang, M.; Yuan, K.; Li, L.; Li, X. Study of the repeated collapsibility of undisturbed loess in Guyuan, China. Bull. Eng. Geol. Environ. 2021, 80, 6321–6330. [Google Scholar] [CrossRef]
- Yu, B.; Fan, W.; Dijkstra, T.A.; Wei, Y.N.; Deng, L.S. Pore structure evolution due to loess collapse: A comparative study using MIP and X-ray micro-CT. Geoderma 2022, 424, 115955. [Google Scholar] [CrossRef]
- Tao, G.L. Fractal Approach on Pore Structure of Rock and Soil Porous Media and Its Applications. Ph.D. Thesis, Wuhan University of Technology, Wuhan, China, 2010. [Google Scholar]
Specific Gravity | Dry Density (g/cm3) | Moisture Content (%) | Plasticity Limit (%) | Liquid Limit (%) | Void Ratio | Particle Composition (mm, %) | ||
---|---|---|---|---|---|---|---|---|
Clay Particle <0.002 | Silt 0.002–0.05 | Sand Grain >0.05 | ||||||
2.70 | 1.57 | 15.24 | 19.57 | 28.33 | 0.72 | 15.9 | 75.1 | 9.0 |
Quartz (%) | Potassium Feldspar (%) | Plagioclase (%) | Calcite (%) | Amphibole (%) | Clay Minerals (%) | Total Content (%) |
---|---|---|---|---|---|---|
42.4 | 2.2 | 20.5 | 9.8 | 1.6 | 23.5 | 100 |
Test Type Gs | Moisture Contentw (%) | Slope k | The Fractal Dimension D | Fitting Factor R2 |
---|---|---|---|---|
Consolidation Test | 15 | 0.3429 | 1.6571 | 0.9301 |
Fractal Dimension D | [0.37, 1.11] | [0.00, 0.37] or [1.11, 1.48] | [1.48, 1.85] | >1.85 |
---|---|---|---|---|
Grain Size Potential Grade | low | medium | high | higher |
Moisture Content w (%) | Confining Pressure (kPa) | Proportion of Large and Medium Pore Volume n (%) |
---|---|---|
15 | 0 | 76.2 |
5 | 100 | 77.6 |
5 | 400 | 53.4 |
25 | 100 | 68.4 |
25 | 400 | 50.5 |
Proportion of Large and Medium Pore Volume | <3.2% | 3.2–10.1% | 10.1–15.6% | >15.6% |
---|---|---|---|---|
Pore Potential Class | low | medium | high | high |
a/mPa−1 | >0.5 | 0.1–0.5 | <0.1 |
---|---|---|---|
Types of Soil | high compressibility | medium compressibility | low compressibility |
δs | <0.015 | 0.015–0.03 | 0.03–0.07 | >0.07 |
---|---|---|---|---|
Collapsibility Grade | none | slight | moderate | intense |
Soluble Salt Content | <5% | 5–10% | 10–13% | >13% |
---|---|---|---|---|
Connection Potential Class | low | medium | high | higher |
Collapsible Type | Self-Weight-Collapsible Loess | Collapsible Loess Without Self-Weight |
---|---|---|
Eutectic Salt (MgSO4, Na2SO4, Na2CO3, NaCl) | 0.46–0.56 | 0.054–0.071 |
Medium Soluble Salt (CaSO4·2H2O) | 0.20–1.04 | 0.20–0.12 |
Insoluble Salt (CaCO3) | 10.75–15.80 | 0.80–14.50 |
Hole Depth (m) | 1.5 | 4.5 | 7.5 | 10.5 | 13.5 | 16.5 | |
---|---|---|---|---|---|---|---|
1# | Size potential | 1.53 | 1.26 | 1.23 | 1.19 | 1.17 | 1.15 |
high | medium | medium | medium | medium | medium | ||
Pore potential | 0.143 | 0.046 | 0.037 | 0.035 | 0.027 | 0.024 | |
high | medium | medium | medium | low | low | ||
Connecting potential | 8.9% | 9.8% | 8.8% | 8.6% | 6.1% | 7.8% | |
medium | medium | medium | medium | medium | medium | ||
2# | Size potential | 1.62 | 1.55 | 1.48 | 1.24 | 1.12 | 1.15 |
high | high | high | medium | medium | medium | ||
Pore potential | 0.174 | 0.166 | 0.156 | 0.039 | 0.022 | 0.022 | |
higher | higher | higher | medium | low | low | ||
Connecting potential | 8.2% | 8.8% | 8.1% | 7.6% | 5.1% | 3.9% | |
medium | medium | medium | medium | medium | low | ||
3# | Size potential | 1.58 | 1.55 | 1.58 | 1.20 | 1.48 | 1.44 |
high | high | high | high | high | high | ||
Pore potential | 0.178 | 0.166 | 0.125 | 0.092 | 0.099 | 0.048 | |
higher | higher | high | medium | medium | medium | ||
Connecting potential | 8.2% | 7.9% | 6.7% | 8.8% | 6.1% | 5.9% | |
medium | medium | medium | medium | medium | low |
Hole Depth (m) | 1.5 | 4.5 | 7.5 | 10.5 | 13.5 | 16.5 | |
---|---|---|---|---|---|---|---|
1# | Void ratio | 1.012 | 1.022 | 1.014 | 0.929 | 0.877 | 0.815 |
Moisture content (%) | 14.7 | 16.9 | 17.4 | 18.3 | 18.4 | 17.6 | |
Collapsibility coefficient and its grade | 0.038 | 0.042 | 0.043 | 0.022 | 0.017 | 0.013 | |
medium | medium | medium | medium | medium | slight | ||
2# | Void ratio | 1.144 | 1.163 | 1.11 | 0.954 | 0.844 | 0.855 |
Moisture content (%) | 13.7 | 11.3 | 12.9 | 16.4 | 17.5 | 17.3 | |
Collapsibility coefficient and its grade | 0.06 | 0.074 | 0.075 | 0.038 | 0.021 | 0.013 | |
intense | intense | intense | medium | medium | slight | ||
3# | Void ratio | 1.147 | 1.146 | 1.113 | 1.08 | 1.07 | 0.96 |
Moisture content (%) | 12.8 | 12.3 | 9.4 | 11.6 | 13.5 | 11.5 | |
Collapsibility coefficient and its grade | 0.072 | 0.095 | 0.08 | 0.06 | 0.042 | 0.032 | |
intense | intense | intense | medium | medium | medium |
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Zhang, Y.; Shao, M.; Li, G.; Chen, C. Macro–Micro Correlation Mechanism Between Structural Potential and Mechanical Strength in Collapsible Loess. Buildings 2025, 15, 1940. https://doi.org/10.3390/buildings15111940
Zhang Y, Shao M, Li G, Chen C. Macro–Micro Correlation Mechanism Between Structural Potential and Mechanical Strength in Collapsible Loess. Buildings. 2025; 15(11):1940. https://doi.org/10.3390/buildings15111940
Chicago/Turabian StyleZhang, Yao, Minghang Shao, Gang Li, and Chenghao Chen. 2025. "Macro–Micro Correlation Mechanism Between Structural Potential and Mechanical Strength in Collapsible Loess" Buildings 15, no. 11: 1940. https://doi.org/10.3390/buildings15111940
APA StyleZhang, Y., Shao, M., Li, G., & Chen, C. (2025). Macro–Micro Correlation Mechanism Between Structural Potential and Mechanical Strength in Collapsible Loess. Buildings, 15(11), 1940. https://doi.org/10.3390/buildings15111940