Finite element modeling approach to assess the stability of debris and rock slopes: a case study from the Indian Himalayas

Landslides and slope failures are recurrent phenomena in the Indian Himalayas. The study area comprises the hill slopes along a road stretch of 1.5 km at a distance of 9 km from Pipalkoti on Chamoli–Badrinath highway (NH-58) in the Garhwal Himalayas, India. Based on the field survey, contour map, and the hillshade, the study area has been divided into different zones. Three different zones/slopes in this study area including one potential debris slide, one stable debris slope, and one potential rock slide have been undertaken for investigation and modeling. Field mapping, data collection related to slope features and soil/rock sample collection, and discontinuity mapping for all the slopes have been carried out in field. Soil samples have been tested in the laboratory to determine the physico-mechanical properties. These properties along with some material properties from the literature have been used as input parameters for the numerical simulation. To investigate the failure process in the debris/rock slides as well as stable debris slope, the slopes were modeled as a continuum using 2D finite element plain strain approach. Shear strength reduction analysis was performed to determine the critical strength reduction factor. The computed deformations and the stress distributions, along the failure surface, have been compared with the field observations and found to be in good agreement. The analysis results indicated rock/debris slide slopes to be highly unstable. The debris slide modeling depicted failures both above and below road levels as observed in field. The rock slide modeling could depict the exact pattern of failure involving 3 sets of discontinuities simultaneously as observed in real-field scenario which is a major limitation in case of limit equilibrium analysis. The field-observed stable slope comes to be stable through FE analysis also. Based on these analyses, landslide hazard assessment of the study area could be done.

[1]  E. Hoek,et al.  Gsi: A Geologically Friendly Tool For Rock Mass Strength Estimation , 2000 .

[2]  J. Z. Zhu,et al.  The finite element method , 1977 .

[3]  D. Varnes.  Landslide hazard zonation: A review of principles and practice , 1984 .

[4]  D. V. Griffiths,et al.  SLOPE STABILITY ANALYSIS BY FINITE ELEMENTS , 1999 .

[5]  P. Aleotti,et al.  Landslide hazard assessment: summary review and new perspectives , 1999 .

[6]  E. G. Richard,et al.  A model for the mechanics of jointed rock , 1968 .

[7]  Evert Hoek,et al.  HOEK-BROWN FAILURE CRITERION - 2002 EDITION , 2002 .

[8]  H. Gerçek,et al.  Poisson's ratio values for rocks , 2007 .

[9]  B. Corkum,et al.  The Shear Strength Reduction Method for the Generalized Hoek-Brown Criterion , 2005 .

[10]  C. J. van Westen,et al.  GIS in landslide hazard zonation : a review, with examples from the Andes of Colombia , 1994 .

[11]  F. Patton.  Multiple Modes of Shear Failure In Rock , 1966 .

[12]  F. Mantovani,et al.  Remote sensing techniques for landslide studies and hazard zonation in Europe , 1996 .

[13]  Manoj K. Arora,et al.  Landslide Susceptibility Zonation (LSZ) Mapping - A Review , 2009 .

[14]  Fausto Guzzetti,et al.  Geographical Information Systems in Assessing Natural Hazards , 2010 .

[15]  M. Arora,et al.  An approach for GIS-based statistical landslide susceptibility zonation—with a case study in the Himalayas , 2005 .

[16]  Robin Chowdhury,et al.  Landslide hazard assessment: summary review and new , 1999 .

[17]  M Rezaei Pazhand Fffff,et al.  SOIL SLOPE STABILITY ANALYSIS BY FINITE ELEMENT , 2004 .

[18]  Martin F. Price,et al.  Mountain Environments and Geographic Information Systems , 1995 .

[19]  I. M. Smith,et al.  Finite element analysis of centrifuged and built-up slopes , 1974 .

[20]  P. Reichenbach,et al.  Landslide hazard evaluation: a review of current techniques and their application in a multi-scale study, Central Italy , 1999 .

[21]  E. Hoeka,et al.  Empirical estimation of rock mass modulus , 2005 .

[22]  Gali Madhavi.  Seismic Stability Analysis of a Himalayan Rock Slope , 2010 .

[23]  Chunguang Li,et al.  On the Assessment of Failure in Slope Stability Analysis by the Finite Element Method , 2008 .

[24]  Tamotsu Matsui,et al.  Finite element slope stability analysis by shear strength reduction technique , 1992 .

[25]  Musharraf Zaman,et al.  Rock slope stability and excavatability assessment of rocks at the Kapikaya dam site, Turkey , 2008 .

[26]  P. K. Kaiser,et al.  Estimation of rock mass deformation modulus and strength of jointed hard rock masses using the GSI system , 2004 .

[27]  Amir M. Kaynia,et al.  Earthquake Stability Analysis of Rock Slopes: a Case Study , 2011, Rock Mechanics and Rock Engineering.

[28]  Sunil Sharma,et al.  SLOPE STABILITY AND STABILIZATION METHODS , 1996 .