Strain-dependent slope stability
- PDF / 1,461,458 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 51 Downloads / 226 Views
(0123456789().,-volV)(0123456789(). ,- volV)
RESEARCH PAPER
Strain-dependent slope stability Kornelia Nitzsche1 • Ivo Herle1 Received: 3 December 2019 / Accepted: 10 April 2020 Ó The Author(s) 2020
Abstract The state of equilibrium of a slope is usually interpreted and expressed by safety factors based on calculations with limit equilibrium methods. Different stress states, failure modes and hydraulic conditions in sections along a slip surface affect the development of shear stresses during slope movement. Moreover, a post-peak softening of the shear strength can have a pronounced impact. As a consequence of the latter effect, the mobilization of the shear resistance along the slip surface is non-uniform and the safety of the slope can be overestimated or underestimated. In the presented paper, an algorithm is proposed to capture the strain-dependent slope stability. The approach is illustrated by means of a calculation example for a slope with a planar slip surface where a block sliding is assumed. Keywords Element test calculations Mobilization of shear strength Slope stability Softening Strain dependence
1 Introduction The prediction of slope stability is an essential task in the geotechnical engineering and other disciplines dealing, for example, with natural risk assessment. In the most cases, variations of the widely spread limit equilibrium method (LEM) are being used, calculating the total driving and resisting actions from forces and/or moments due to soil weight, surcharges, pore water pressures, anchor forces, etc. Regarding the soil resistance, shear strength in terms of friction angle u and cohesion c is usually assumed using the Mohr–Coulomb criterion. The ratio of resisting to driving actions yields a numerical value of the factor of safety (FOS) which helps to interpret the state of a slope. A common LEM is the method of slices developed in several versions during the last century [2, 12, 23, 29, among others]. One disadvantage of this method is a rough approximation of the stress state along the selected slip surface as only the soil own weight and surcharges but not the stress history is considered. To overcome this aspect, approaches combining the finite element method (FEM) for
& Kornelia Nitzsche [email protected] 1
Institute of Geotechnical Engineering, Technische Universita¨t Dresden, George-Ba¨hr-Str. 1a, 01069 Dresden, Germany
calculating stresses in a soil mass with the LEM were proposed [13, 18]. A further development linking the FEM with slope stability analyses resulted in a so-called strength reduction method (SRM) [6, 10, 11, 15, 19, 20, 22, 24, 32, 33, among others]. An important feature of the SRM is a natural evolution of the critical slip surface in an arbitrary slope during the shear strength reduction [35]. Herein, a factor of safety can be determined directly from the FEM analysis independently of the LEM. However, in spite of a few attempts [27], the application of the SRM is practically limited to the perfectly plastic soil behaviour represented
Data Loading...
