Hydraulic‐Mechanical Properties of Unsaturated Granite‐Weathered Residual Soil in Korea

Abstract

Core Ideas We examine SWCC and shear strength under various stress states and suction levels. Relevant effective stress for granite‐weathered residual soil in Korea is proposed. We propose a numerical framework for strength analysis with transient infiltration. Potential failure mechanisms of civil infrastructure under rainfall are explored. We suggest using stress‐dependent SWCC in strength analysis. This study performed a series of experiments to examine the hydraulic‐mechanical properties of granite‐weathered residual soil in the Korean Peninsula. Particular attention was paid to the soil‐water characteristic curve (SWCC) and shear strength under various stress states and matric suction levels. The experimental results indicated the decisive influence of the stress state on the SWCC, notably in the low range of matric suction. In addition, the evolution of shear strength with suction became significant under high net confining stress. The effective stress using the stress‐independent SWCC could not describe the actual mechanical behaviors of the unsaturated soil. The relevant effective stress for the granite‐weathered residual soil in consideration was then proposed. Next, a numerical framework for strength analysis with infiltration was developed to manifest the practical applications of the experimental results. The analysis results revealed the potential failure mechanisms of the geotechnical infrastructures induced by rainfall. Ignoring the contribution of matric suction may lead to overly conservative outcomes and cannot capture the realistic performance of soil under the rainfall condition. Moreover, the stress‐dependent hydraulic properties are suggested for application in strength analysis for the safer design of geotechnical infrastructure.

Failure mode of rainfall-induced landslide of granite residual soil, southeastern Guangxi Province, China

“…Rainfall-induced landslides are the most common geohazards in the tropical and subtropical areas covered by granite residual soil, such as Brazil (Lacerda, 2007;Coutinho et al, 2019), Singapore (Rezaur et al, 2003;Rahardjo et al, 2008Rahardjo et al, , 2012Zhai et al, 2016;Zhang et al, 2019), Malaysia (Rahman et al, 2018), Korea (Kim et al, 2004;Pham et al, 2019), southern (Jiao et al, 2005;Fan et al, 2018;Luo et al, 2021;Liu et al, 2020aLiu et al, , b, 2021 and southeastern China (Xia et al, 2019;Yao et al, 2021;Shu et al, 2021;Zhao et al, 2021). Guangxi is located in southeastern China, where granite is concentrated in the southeast and landslides occur frequently (Liao et al, 2019).…”

“…Second, the increase in soil-water content and pore water pressure can lead to a decrease in slope stability (Gasmo et al, 2000;Rezaur et al, 2003;Rahardjo et al, 2005Rahardjo et al, , 2008Lacerda, 2007). Thus, in the process of landslide formation, the variation of physical property parameters such as moisture, matric suction or pore pressure plays an important role in the residual soil landslide (Kassim et al, 2012;Igwe and Fukuoka, 2014;Pham et al, 2019;Zhai et al, 2016). Rainfall-triggered mechanisms focus on completely weathered granite fill slope in Hong Kong SAR, China.…”

Failure mode of rainfall-induced landslide of granite residual soil, southeastern Guangxi province, China

“…Rainfall-induced landslides are the most common geohazards in the tropical and subtropical areas covered by granite residual soil, such as Brazil (Lacerda, 2007;Coutinho et al, 2019), Singapore (Rezaur et al, 2003;Rahardjo et al, 2008;Harianto et al, 2012;Zhai et al, 2016;Zhang et al, 2019), Malaysia (Rahman et al, 2018), Korea (Kim et al, 2004;Pham et al, 2019), the southern (Jiao et al, 40 2005;Luo et al, 2021;Liu et al, 2021;Liu et al, 2020a;Liu et al, 2020b) and southeastern China (Xia et al, 2019;Yao et al, 2021;Shu et al, 2021;Zhao et al, 2021). Guangxi is located in southeastern China, where granite is concentrated in the southeast, and landslides occur frequently (Liao et al, 2019).…”

“…Second, the increase in soil water content and pore water pressure can 70 lead to a decrease in slope stability (Gasmo et al, 2000;Rezaur et al, 2003;Rahardjo et al, 2005;Lacerda, 2007;Rahardjo et al, 2008). Thus, in the process of landslide formation, the variation of physical property parameters such as moisture, matric suction or pore pressure play an important role in the residual soil landslide (Kassim et al, 2012;Igwe and Fukuoka, 2014;Pham et al, 2019;Zhai et al, 2016). Rainfall triggered mechanisms focus on completely weathered granite fill slope in Hong 75 Kong, China.…”