Reservoir Regulation for Control of an Ancient Landslide Reactivated by Water Level Fluctuations in Heishui River, China
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ISSN 1674-487X
Reservoir Regulation for Control of an Ancient Landslide Reactivated by Water Level Fluctuations in Heishui River, China Jian Guo
1
, Mo Xu *1, Qiang Zhang1, Xianxuan Xiao1, Shishu Zhang2, Shaoming He2
1. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China 2. PowerChina Chengdu Engineering Corporation Limited, Chengdu 610072, China Jian Guo: https://orcid.org/0000-0003-0359-8354; Mo Xu: https://orcid.org/0000-0002-7470-7274 ABSTRACT: Due to the complex geological processes of Qinghai-Tibet Plateau, numerous deposits, especially the large-scale ancient landslide deposits, are characteristic features of the valleys incised in southwestern China. Intense water level fluctuations since 2011 in Maoergai Reservoir, China, registered the reactivation of Xierguazi ancient landslide, and presented a significant risk to neighboring facilities. Based on detailed field survey and drilling exploration, the landslide was divided into Zone A and Zone B, and other characterizations of landslide were studied as well. To precisely measure the extent of landslide displacement during filling and drawdown stage, surface displacement monitoring system was deployed on the landslide. The monitoring analyses data reveal that reservoir fluctuation is the dominant factor influencing landslide displacement, especially during drawdown stage. Moreover, a future sliding is anticipated in Zone A, while a creep had already existed in Zone B. A reservoir regulation was then established using the lead-lag correlation between reservoir fluctuation and landslide displacement and landslide stability analysis. In the end, the follow-up deformation monitoring demonstrates that the reservoir regulation controlled the landslide effectively. Landslide control by reservoir regulation in Maoergai can serve as a case study for other settlements involved in similar construction activities. KEY WORDS: ancient landslide, reactivation, reservoir regulation, displacement monitoring, correlation analysis. 0
INTRODUCTION Ancient landslides are referred to as failure of slopes which had occurred in the Late Pleistocene or earlier, and are relatively stable in modern times (Jiao et al., 2013; Chang et al., 2012; Pánek et al., 2009, 2008). Although ancient landslides can be reactivated by a variety of influencing factors, the reactivation of reservoir landslides is a more frequent and hazardous phenomenon, especially in those deep valleys where the reservoirs are completed and filled (Zhao et al., 2015; Dong et al., 2014; Dewitte et al., 2006). To date, many methods have been developed and introduced to precisely measure and predict landslide movement, and a strong relationship between fluctuation of reservoir level and reactivation of ancient landslide, both qualitative and quantitative, has been widely reported in recent literatures. Superimposed effect of triggering factors and non-linear displacement trends make the early warning and emergency disposal of ancient landsl
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