Effect of weathering on short‐ and long‐term mechanical behaviour of granitic soils from the Benggang area under unloading conditions

• Published in: Earth surface processes and landforms Vol. 48; no. 9; pp. 1883 - 1894
• Main Authors: Zhang, Wan‐lu, Chen, Jia‐cun, Yuan, Zai‐jian, Liao, Yi‐shan, Feng, Ren
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.07.2023
• Subjects: Accelerated erosion; Benggang landforms; Comparative analysis; Comparative studies; Compression; Copper; creep behaviour under unloading conditions; Creep tests; decomposed granite; Deformation; Disintegration; Geological processes; Initial stresses; Instability; Landforms; Mechanical properties; Regional development; Shear stress; Soil conditions; Soil erosion; Soil mechanics; Soil stability; Solifluction; stress release; Time dependence; Triaxial tests; Unloading; Weathering; weathering degree
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.5582

As regional soils collapse during the development of Benggang landforms, the release of geostress results in soil disintegration. This phenomenon is associated with soil instability, and it necessitates a study on the mechanical behaviour of decomposed granitic soils in response to unloading in the Benggang area. This study addressed the short‐ and long‐term mechanical behaviour of granitic soils with various degrees of weathering in response to unloading. Triaxial unloading and multi‐stage unloading creep tests were performed, including a comparative study of consolidated undrained (CU) triaxial tests. The deformation characteristics of granitic soils differed with the degree of weathering and the initial stress level. The most significant adverse effect of creep behaviour under unloading and undrained conditions was found in granitic soils with the greatest loss rate of maximum shear stress in contrast to the cases of CU compression and one‐time unloading. Additionally, increasing time‐dependent deformation was observed with increasing degree of weathering and initial stress level, which suggested that creep behaviour under unloading conditions accelerated soil erosion and instability in the Benggang area. The results of this study highlighted the potential influences of geostress release and time‐dependent deformation on soil instability in the Benggang area and advanced the understanding of mechanical mechanisms during the development of Benggang landforms. As regional soils collapse during the development of Benggang landforms, the release of geostress results in soil disintegration. This study addressed the short‐ and long‐term mechanical behaviour of granitic soils with various degrees of weathering in response to unloading. It was found that increasing time‐dependent deformation was observed with an increase in the weathering degree and initial stress level, suggesting that the unloading creep behaviour accelerates soil erosion and the instability of the soil mass in the Benggang area. This study highlights the potential of geostress release and time‐dependent deformation for the disintegration of soils in the Benggang area, further facilitating the understanding of mechanical instability during the development of Benggang landforms.