Vol19 No.6: 1509-1524
【Title】Failure mechanisms and risk mitigation of check dams on the Chinese Loess Plateau: A case study at the Gutun Gully
【Author】JIANGRui-jun1 ; ZHANGMao-sheng 1,2*;FENG Li2; SUNPing-ping3
【Addresses】1 Department of Geological Engineering, Chang'an University, Xi'an, Shaanxi 710054, China; 2 Department of Civil Engineering, School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China; 3 Key Laboratory for Geo-hazards in Loess Area, Ministry of Natural Resources, Xi'an Center of China Geological Survey, Xi'an 710054, China
【Corresponding author】ZHANG Mao-sheng
【Citation】Jiang RJ, Zhang MS, Feng L, Sun PP (2022) Failure mechanisms and risk mitigation of check dams on the Chinese Loess Plateau: A case study at the Gutun Gully. Journal of Mountain Science 19(6). https://doi.org/10.1007/s11629-021-6927-8
【Abstract】: Loess is long-term aeolian dust deposition, characterized by loose structure, concentrated participle distribution and unstable mineral composition, and thus easy to cause extensive collapsibility and have general water sensitivity. To reveal the difference in water sensitivity between naturally intact (NI) loess and mechanically compacted (MC) loess used for the check dam, the transient water release and imbibition method (TRIM)was used to acquire the suction stress–expanded hydraulic characteristic curves for the NI and MC loess and explore possible approaches for formulating the potential of loess water sensitivity. Based on the Local Field of Safety (LFS) associated with slope stability, we constructed a finite element model of a check dam to depict its failure processes under different rainfall scenarios. The results revealed the strong water sensitivity in NI loess, while the MC loess retained a certain water-sensitive potential. Thiscapacity depends on the ‘water sensitivity coefficient' obtained from the suction-stress characteristic curve, which better presented the deformation potential of the two loess samples at different water content levels. In the context of LFS, we identified two failure patterns in the dam body that were involved in loess water sensitivity under hydromechanical conditions: rainfall erosion-induced shallow mudflow failure, and preferential-infiltration progressive failure. These patterns may provide new insights into dam-breakage mechanisms and potential chain effects of check damson the Chinese Loess Plateaufrom the perspective of soil–water interactions, which is vital for predicting the position and timing of check dam failure, and mitigating risks.
【Keywords】Chinese loess; Water sensitivity; Suction stress; Failure patterns;Slope stability; Check dam