Nestled high in the Eastern Tibetan Plateau, the Luanshibao Landslide region is home to an abundance of granite, a resilient rock that has long withstood the challenges of this rugged landscape. However, a new study published in Scientific Reports has uncovered how the relentless freeze-thaw cycles in this area can significantly compromise the strength and durability of granite over time. This knowledge could prove vital in evaluating the stability of rock slopes and engineering structures in the Tibetan Plateau, where climate change and extreme weather events pose growing threats.
Deciphering the Freeze-Thaw Damage to Granite
The researchers, led by a team from Northwest University and the Chinese Academy of Geological Sciences, set out to investigate the effects of repeated freeze-thaw cycles on the mechanical and microstructural properties of granite samples from the Luanshibao Landslide region. By subjecting the granite to a range of freeze-thaw conditions, they were able to track the deterioration of the rock’s strength and overall integrity.
Uniaxial compression tests revealed that the number of freeze-thaw cycles had a more pronounced impact on the granite’s compressive strength than the actual freezing temperature. As the cycles increased, the rock’s stress-strain behavior shifted, displaying a distinct four-stage pattern of compression, densification, crack initiation, and eventual rupture.
Brazilian splitting tests further demonstrated the profound effect of freeze-thaw on the granite’s tensile properties. The researchers observed the progression of damage, from initial compression and densification to the propagation of cracks and ultimate failure. Interestingly, the traditional linear models used to predict tensile strength were found to be insufficient, underscoring the need for more sophisticated approaches.
Unveiling the Microstructural Changes
To understand the mechanisms behind the granite’s deterioration, the researchers turned to scanning electron microscopy (SEM) analysis. The SEM images revealed a stark evolution of the rock’s microstructure, with freeze-thaw cycles causing significant pore expansion and fracture propagation. This microstructural damage was directly linked to the observed weakening of the granite’s mechanical properties.
Developing a Robust Joint Strength Model
Recognizing the limitations of traditional strength criteria, the research team proposed a joint strength model that could more accurately capture the complex interplay of tensile, compressive, and shear stresses experienced by the granite under freeze-thaw conditions. This model provides a more comprehensive assessment of the rock’s behavior, with potential applications in evaluating the stability of rock slopes and the durability of engineering structures in the Tibetan Plateau.
Implications for Infrastructure and Disaster Mitigation
The findings of this study hold crucial implications for infrastructure development and disaster risk management in the Tibetan Plateau. As the region grapples with the impacts of climate change, including more frequent and intense freeze-thaw cycles, understanding the vulnerabilities of local rock materials like granite becomes paramount. This knowledge can inform the design and construction of more resilient roads, railways, and other critical infrastructure, while also aiding in the assessment and mitigation of geological hazards, such as landslides and rockfalls, that threaten the region’s communities.
This article is based on research by Lirong Qi, Jiading Wang, Dengfei Zhang, Yongshuang Zhang, and Jianfei Ma.
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