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| Long-term strength degradation and microscale mechanisms of stabilized high-plateau soft soil under freeze-thaw cycles |
| HOU Xiaoqiang1*, FAN Hongjuan1, HUANG Jiefang2, GUO Shirong3, REN Jianqiang1, WANG Chen1, LI Siyuan1 |
(1. College of Civil Engineering, Lanzhou Jiaotong University, Lanzhou, Gansu 730070, China; 2. CCCC First Highway Engineering Group Co., Ltd., Beijing 100020, China; 3. Railway Engineering Co., Ltd., China Railway 22nd Bureau Group
Corporation Limited, Beijing 100006, China) |
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Abstract To enhance the long-term service performance of solidified soft soil in plateau regions, this study employed ordinary Portland cement for stabilization. A series of unconfined compression tests, direct shear tests, and microstructural characterization techniques (XRD, SEM, NMR) were utilized to systematically investigate the strength deterioration patterns of cement-stabilized soil under freeze-thaw cycles and elucidate the intrinsic relationship between macroscopic mechanical behavior and microscopic mechanisms. The results show that the strength deterioration of cement-stabilized soil exhibits distinct stage characteristics. The first five freeze-thaw cycles result in the most significant strength reduction, with markedly diminished effects observed thereafter, identifying this initial phase as the critical period for strength degradation. A predictive model based on a 30-year service life established strength deterioration thresholds. The stress-strain curves reveal a three-stage evolution, with specimens demonstrating similar strength development trends in the linear elastic stage across all cement contents, followed by a sharp stress drop post-peak, indicating a notable transition from plastic to brittle failure. The incorporation of cement significantly enhances soil strength, with the unconfined compressive and shear strengths of specimens containing 4%–10% cement after 10 freeze-thaw cycles substantially exceeding those of untreated soil. The increase in cohesion was significantly more pronounced than that of the internal friction angle. Microstructural analysis indicates that repeated freeze-thaw cycles weaken interparticle bonding, reduce particle contacts, and promote pore evolution and development, thereby providing a microscopic interpretation of the macroscopic strength deterioration mechanisms. These findings offer theoretical and technical support for the application of soil stabilization technologies in cold plateau regions.
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2026, Vol. 45 
