Short communication
Analysis of physico-mechanical properties and pore structure characteristics of thermally damaged sandstone
Junqiao Yu, Yun Wu*, Jiamin Wang*, Lei Wang, Lihua Hu, Jian Lin
Deep Resources Engineering. 2025, 2(4): 100188. 
doi.org10.1016j.deepre.2025.100188.pdf
Abstract: Under the conditions of underground coal gasification (UCG), the pore structure and mechanical properties of overlying rocks are crucial for the stability of surrounding strata. Therefore, it is of great significance to investigate the thermal damage of surrounding rocks. In this study, the variations in apparent characteristics, mass, P-wave velocity, porosity and strength of sandstone after high temperature from room temperature to 800 ℃. The results indicate that the physical and mechanical properties of sandstone exhibit different degrees of variation after being subjected to high temperatures. Macropores complexity peaks at 400 ℃ then weakens due to crack network simplification, while mesopores regularity linearly increases with cementation loss. Porosity growth rate shows three-stage escalation through thresholds at 200 ℃ and 600 ℃, rising from 3.81% (25 ℃) to 18.70% (800 ℃). The mechanism of sandstone damage caused by high temperatures has been explored based on microscopic thin-section analysis, and the findings of the research can offer a insights for the evaluation of rock damage in underground coal gasification.
Highlights:
• The damage mechanism of sandstone at high temperature is studied by NMR and microscopic thin-section analysis.
• The relationship between fractal dimension of sandstone pore structure and mechanical properties is studied.
• The research results provide a reference for evaluating the rock damage in underground coal gasification (UCG).
Keywords: Underground coal gasification (UCG); High temperature; Pore structure; Fractal dimension; Physical and mechanical properties
Cite: Yu, J.Q.; Wu, Y.; Wang, J.M.; Wang, L.; Hu, L.H.; Lin, J., Analysis of physico-mechanical properties and pore structure characteristics of thermally damaged sandstone. Deep Resources Engineering 2025, 2 (4): 100188. https://doi.org/10.1016/j.deepre.2025.100188
Citations: ……
