Effects of seismic force and pore water pressure on stability of 3D unsaturated hillslopes
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Effects of seismic force and pore water pressure on stability of 3D unsaturated hillslopes Long Wang1 · Wenhua Liu1 · Wei Hu2 · Wugang Li1 · De’an Sun2,3 Received: 15 July 2020 / Accepted: 17 October 2020 © Springer Nature B.V. 2020
Abstract Three-dimensional (3D) kinematic limit analysis of unsaturated hillslopes is presented in this paper. Different from the traditional two-dimensional (2D) mechanism based on the infinite slope model, the 3D failure mechanism is more rational for its advantage in taking the out-of-plane geometries and soil properties into consideration. The soils in engineering practice are mostly unsaturated in nature and are commonly characterized with an arbitrary distribution of the moisture content, i.e., the matric suction, and therefore the formation of the work balance equation becomes much more elaborated using traditional methods. To tackle the nonlinear features of matric suction, a semi-analytical method is presented and is validated through comparisons with the benchmark solutions. The hillslope stability under seismic and pore water pressure conditions are both numerically studied. The results are presented in forms of graphs for a practical range of parameters, indicating the significance in accounting for the influences of 3D constraints, seismic loads and pore water pressures in hillslope stability assessments. Keywords Hillslope · Unsaturated soil · Limit analysis · Seismic force · Pore water pressure
1 Introduction Stability estimations of hillslopes are classical issues in engineering practice and are usually performed using 2D infinite slope models (Cornforth 2005). In these analyses, the stability problem is treated as a plane-strain issue with the sliding soil mass postulated to move parallelly along a plane failure surface. Because of its simplicity in geometric assumptions, this model is frequently adopted in hillslope safety evaluations, particularly for shallow landslides (e.g., Ray et al. 2010; Godt et al. 2012; Lee and Park 2016; Conte et al. 2017; Pham et al. 2018). The hillslope length, however, is not actually infinite and the * Wei Hu [email protected] 1
School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China
2
State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection, Chengdu University of Technology, 1 Erxianqiao Dongsan Road, Chengdu 610059, China
3
Department of Civil Engineering, Shanghai University, Shanghai 200444, China
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prediction of the infinite slope model is too conservative when the length-to-height ratio is relatively small (Milledge et al. 2012). Furthermore, the potential slip surface would be deeper and larger when the hillslope is subjected to long-lasting rainfall episodes, and at this moment, conspicuous 3D features of the slip surface can be observed (Zêzere et al. 2005), especially for hillslopes restricted by exposed rocks and neighboring geotechnical structures. A proper consideration of the slope geometry warrants an accurate prediction o
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