The 2015 Shenzhen catastrophic landslide in a construction waste dump: analyses of undrained strength and slope stabilit
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RESEARCH PAPER
The 2015 Shenzhen catastrophic landslide in a construction waste dump: analyses of undrained strength and slope stability Liang-tong Zhan1 • Xiao-gang Guo1
•
Qian-qian Sun1 • Yun-min Chen1 • Zu-yu Chen2
Received: 8 March 2020 / Accepted: 12 September 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The 2015 catastrophic landslide in a 110-m-high waste dump in Shenzhen is recognized as one of the largest landfill failure worldwide. An earlier comprehensive field investigation revealed that the dominant component of the fill was completely decomposed granite (CDG), and the dumping operation was accompanied by a rise of the groundwater level. In this paper, the complex stress paths for the initially unsaturated fill materials being subjected to both rapid filling and wetting were investigated. A simplified method was proposed for estimating the gain of undrained shear strength under the complex stress paths. Soil samples were taken from the site to a laboratory to measure the undrained shear strength and validate the estimation method. Total stress-based stability analyses were carried out to calculate the factor of safety of the dump at failure. The triggering mechanism of the landslide is clarified as follows: The gain of shear strength with the surcharge loading for the wet layer in the lower part of the waste dump was limited by a build-up of excess pore-water pressure. The gain of shear strength for the relatively dry fill material was attenuated with the rise of groundwater level. When the shear strength was not enough to resist the increasing slip force with the surcharge loading, a deep-seated translational failure took place in the lower wet layer of the waste dump. The proposed method for analyses of undrained strength and slope stability are proven to be applicable to the waste-dumping operation with rapid filling and rising groundwater level. Keywords Construction waste dump Completely decomposed granite Slope stability Total stress based analysis Undrained shear strength Wetting
1 Introduction Accompanying the rapid urbanization in China in recent years, construction waste (CW) has dramatically increased in many cities. Taking Shenzhen, one of the largest cities in China, as an example, the volume of CW yielded per year was approximately 3.6 9 107 m3 from 2013 to 2015 [7]. Approximately 61% of the CW was transported to waste dumps for landfilling. More than 40 waste dump sites have been constructed or are planned to be constructed in Shenzhen. As the most common way to dispose of CW, landfilling is often accompanied by the risk of landslides. & Xiao-gang Guo [email protected] 1
MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China
2
China Institute of Water Resources and Hydropower Research, Beijing 100044, China
On 20 December 2015, a catastrophic landslide occurred in a 110-m-high waste dump located in Guangming New District, Shenzhen,
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