Subsurface multi-physical characterization of mountain excavation and city construction in loess plateau with a fiber-optic sensing system

• Published in: Journal of Rock Mechanics and Geotechnical Engineering Vol. 16; no. 8; pp. 2935 - 2946
• Main Authors: Liu, Jie, Shi, Bin, Gu, Kai, Sun, Meng-Ya, Yao, Jun-Cheng, Han, He-Ming
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2024; Elsevier
• Subjects: Compacted loess; Fiber-optic monitoring; Mountain excavation and city construction; Multi-physical characterization; Fiber-optic monitoring; Compacted loess; Multi-physical characterization; Mountain excavation and city construction
• ISSN: 1674-7755
• DOI: 10.1016/j.jrmge.2023.09.026

Mountain excavation and city construction (MECC) projects being launched in the Loess Plateau in China involve the creation of large-scale artificial land. Understanding the subsurface evolution characteristics of the artificial land is essential, yet challenging. Here, we use an improved fiber-optic monitoring system for its subsurface multi-physical characterization. The system enables us to gather spatiotemporal distribution of various parameters, including strata deformation, temperature, and moisture. Yan'an New District was selected as a case study to conduct refined in-situ monitoring through a 77 m-deep borehole and a 30 m-long trench. Findings reveal that the ground settlement involves both the deformation of the filling loess and the underlying intact loess. Notably, the filling loess exhibits a stronger creep capability compared to underlying intact loess. The deformation along the profile is unevenly distributed, with a positive correlation with soil moisture. Water accumulation has been observed at the interface between the filling loess and the underlying intact loess, leading to a significant deformation. Moreover, the temperature and moisture in the filling loess have reached a new equilibrium state, with their depths influenced by atmospheric conditions measuring at 31 m and 26 m, respectively. The refined investigation allows us to identify critical layers that matter the sustainable development of newly created urban areas, and provide improved insights into the evolution mechanisms of land creation. •A fiber-optic monitoring system was used for the subsurface multi-physical characterization.•The spatiotemporal profiles of strain, temperature, and moisture in the in the anthropogenic land were reported.•Loess deformation at different depths was analyzed under the combined thermo-hydro-mechanical effects.•Improved insights into the evolution mechanisms of land creation were provided based on the abundant dataset.