Strength behavior of slip-zone soils of landslide subject to the change of water content
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Strength behavior of slip-zone soils of landslide subject to the change of water content Ting-Kai Nian • Zhong-Kai Feng • Peng-Cheng Yu • Hui-Jun Wu
Received: 20 September 2011 / Accepted: 13 March 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract Landslides are the major natural hazards in many countries all over the world and are usually caused by heavy rainfall, water level change of reservoir, excavation, earthquake, etc. Whether the landslide occurs or not in rainfall season, the strength variation of slip-zone soils of landslide is regarded as the vital control factor. Thus, strength behavior for slip-zone soils of landslide subject to the change of water content is required to be evaluated in a potential landslide area. In this paper, the shear strength of typical slipzone soil, six groups of 25 specimens of remolded clay samples from Daxishan reservoir landslide, was systemically investigated using the improved direct shear test apparatus in order to fully understand its physical and mechanical properties, and also the shear and failure behavior. Furthermore, the fitting equations for expressing the relationship between the shear strength (effective cohesion and internal friction angle) and vertical loadings, initial water contents of slip-zone clay were established based on the experimental results. In particular, a series of shear stress–shear strain curves under various vertical loadings and different water contents were observed. The results show that a ‘‘softening’’ stress–strain behavior is achieved for unsaturated slip-zone soil, while a ‘‘hardening’’ curve is found for saturated slip-zone soil. Keywords Landslide Soil mechanics Slip-zone soil Shear strength behavior Water content
T.-K. Nian (&) Z.-K. Feng P.-C. Yu H.-J. Wu Department of Geotechnical Engineering, School of Civil Engineering, Dalian University of Technology (DUT), Dalian 116024, China e-mail: [email protected] T.-K. Nian Z.-K. Feng P.-C. Yu H.-J. Wu State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology (DUT), Dalian 116024, China
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Nat Hazards
1 Introduction Landslides are the major natural hazards in many countries all over the world and are usually caused by heavy rainfall, water level change of reservoir, earthquake, hurricanes, storm waves or rapid stream erosion, etc. (Sassa et al. 2005; Wang and Li 2009; Yalcin 2011). These effects increase the shear stress or reduce the shear strength of soils in the slope/ landslide; especially, the intense rainfalls generate a rapid increase in pore water pressure in the unsaturated zone and groundwater flow in the saturated area which can give rise to slope instability or reactivation of landslides (Yalcin 2011). The slip-zone soil, the most sensitive region of bands in the existing or potential landslides, its behavior can be subjected to the change of water content due to the rainfalls or reservoir water level fluctuation. Some researchers investigated the physical and mechanical behavior of the slip-zone soils
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