Investigation and monitoring on a rainfall-induced deep-seated landslide
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ORIGINAL PAPER
Investigation and monitoring on a rainfall-induced deep-seated landslide Momo Zhi 1 & Yuequan Shang 1 & Yu Zhao 1 & Qing Lü 1 & Hongyue Sun 2
Received: 8 July 2014 / Accepted: 6 November 2015 # Saudi Society for Geosciences 2016
Abstract The ground movement of Xiashan village landside of Zhejiang province, China, commenced in 1958 due to typhoon rainstorms followed by two subsequent slips in 1989 and 2001. The reactivation of the large-scale landslide has become a serious concern to the safety of a nearby reservoir and the local villagers. A pilot testing program was established in 2007 using a variety of landslide monitoring facilities. The slope is of a chair-shaped form with Quaternary residual soil overlying the Pliocene sedimentary and basalt layers. The pilot test program included GPS, inclinometers of conventional and fixed types, piezometer, and rain gauge. Two potential sliding planes were identified in the inclinometers showing the possible slip mode along more than one bedding plane. A shallow slip surface dipping a low angle (10°) lies in the residual soil, while a deep slip surface is located along the weak plane within the Pliocene strata. The piezometer reading indicated high groundwater level and a certain level of correlation with the displacement velocity. A critical groundwater depth was determined, and its usage as a warning threshold was discussed. In view of the very important location about an existing dam, it is strongly recommended that surface and internal drainage facilities be provided to ensure the longterm stability of the landslide.
Keywords Landslide . Rainfall . Monitoring . Groundwater
* Yu Zhao [email protected] 1
Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China
2
Department of Ocean Engineering, Zhejiang University, Hangzhou 310058, China
Introduction The rainfall-induced landslides occur every year in almost all mountainous areas throughout the world. Zhejiang province located in the southeast of China is prone to rainfall-induced landslides. There were more than 240 landslides occurred in Zhejiang territory which caused five casualties, six injuries, and more than 40 million RMB economical loss in 2014. Clear understanding of triggering mechanism and proper warning systems is of great significance for disaster mitigation especially for the mitigation of catastrophic landslides. Seasonal intense rainfalls are recognized to be a primary triggering factor causing slope instability in sub-tropical regions (Tsaparas et al. 2003; Ng and Menzies 2007; Li et al. 2011; Leung and Ng 2013). The cause-effect relation has been studied and verified through detailed field investigation, field monitoring, numerical calculation, etc. Slope failures were related to groundwater conditions such as rainfall infiltration, antecedent moisture, and rainfall history (Wieczorek 1996). Wilson (1989) suggested that the buildup of water pressure in slopes caused by rainfall was the trigger of landslide. Recently, the studies on rainfall thresholds for th
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