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Slope Stability (slope + stability)

Distribution by Scientific Domains
Earth and Environmental Science83%

Terms modified by Slope Stability

  • slope stability analysis
    		•

    Selected Abstracts

    A low-dimensional physically based model of hydrologic control of shallow landsliding on complex hillslopes

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2008
    Ali Talebi
    Abstract Hillslopes have complex three-dimensional shapes that are characterized by their plan shape, profile curvature of surface and bedrock, and soil depth. To investigate the stability of complex hillslopes (with different slope curvatures and plan shapes), we combine the hillslope-storage Boussinesq (HSB) model with the infinite slope stability method. The HSB model is based on the continuity and Darcy equations expressed in terms of storage along the hillslope. Solutions of the HSB equation account explicitly for plan shape by introducing the hillslope width function and for profile curvature through the bedrock slope angle and the hillslope soil depth function. The presented model is composed of three parts: a topography model conceptualizing three-dimensional soil mantled landscapes, a dynamic hydrology model for shallow subsurface flow and water table depth (HSB model) and an infinite slope stability method based on the Mohr,Coulomb failure law. The resulting hillslope-storage Boussinesq stability model (HSB-SM) is able to simulate rain-induced shallow landsliding on hillslopes with non-constant bedrock slope and non-parallel plan shape. We apply the model to nine characteristic hillslope types with three different profile curvatures (concave, straight, convex) and three different plan shapes (convergent, parallel, divergent). In the presented model, the unsaturated storage has been calculated based on the unit head gradient assumption. To relax this assumption and to investigate the effect of neglecting the variations of unsaturated storage on the assessment of slope stability in the transient case, we also combine a coupled model of saturated and unsaturated storage and the infinite slope stability method. The results show that the variations of the unsaturated zone storage do not play a critical role in hillslope stability. Therefore, it can be concluded that the presented dynamic slope stability model (HSB-SM) can be used safely for slope stability analysis on complex hillslopes. Our results show that after a certain period of rainfall the convergent hillslopes with concave and straight profiles become unstable more quickly than others, whilst divergent convex hillslopes remain stable (even after intense rainfall). In addition, the relation between subsurface flow and hillslope stability has been investigated. Our analyses show that the minimum safety factor (FS) occurs when the rate of subsurface flow is a maximum. In fact, by increasing the subsurface flow, stability decreases for all hillslope shapes. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Effects of forest harvesting on the occurrence of landslides and debris flows in steep terrain of central Japan

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2008
    Fumitoshi Imaizumi
    Abstract Landslides and debris flows associated with forest harvesting can cause much destruction and the influence of the timing of harvesting on these mass wasting processes therefore needs to be assessed in order to protect aquatic ecosystems and develop improved strategies for disaster prevention. We examined the effects of forest harvesting on the frequency of landslides and debris flows in the Sanko catchment (central Japan) using nine aerial photo periods covering 1964 to 2003. These photographs showed a mosaic of different forest ages attributable to the rotational management in this area since 1912. Geology and slope gradient are rather uniformly distributed in the Sanko catchment, facilitating assessment of forest harvesting effects on mass wasting without complication of other factors. Trends of new landslides and debris flows correspond to changes in slope stability explained by root strength decay and recovery; the direct impact of clearcutting on landslide occurrence was greatest in forest stands that were clearcut 1 to 10 yr earlier with progressively lesser impacts continuing up to 25 yr after harvesting. Sediment supply rate from landslides in forests clearcut 1 to 10 yr earlier was about 10-fold higher than in control sites. Total landslide volume in forest stands clearcut 0 to 25 yr earlier was 5·8 × 103 m3 km,2 compared with 1·3 × 103 m3 km,2 in clearcuts >25 yr, indicating a fourfold increase compared with control sites during the period when harvesting affected slope stability. Because landslide scars continue to produce sediment after initial failure, sediment supply from landslides continues for 45 yr in the Sanko catchment. To estimate the effect of forest harvesting and subsequent regeneration on the occurrence of mass wasting in other regions, changes in root strength caused by decay and recovery of roots should be investigated for various species and environmental conditions. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    An integrated hydrological model for rain-induced landslide prediction

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2002
    P. L. Wilkinson
    Abstract This paper describes an extension to the Combined Hydrology And Stability Model (CHASM) to fully include the effects of vegetation and slope plan topography on slope stability. The resultant physically based numerical model is designed to be applied to site-specific slopes in which a detailed assessment of unsaturated and saturated hydrology is required in relation to vegetation, topography and slope stability. Applications are made to the Hawke's Bay region in New Zealand where shallow-seated instability is strongly associated with spatial and temporal trends in vegetation cover types, and the Mid-Levels region in Hong Kong, an area subject to a variety of landslide mechanisms, some of which may be subject to strong topographic control. An improved understanding of process mechanism, afforded by the model, is critical for reliable and appropriate design of slope stabilization and remedial measures. Copyright © 2002 John Wiley & Sons, Ltd. [source]

    The use of an SQP algorithm in slope stability analysis

    INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 1 2005
    Jian Chen
    Abstract In the upper bound approach to limit analysis of slope stability based on the rigid finite element method, the search for the minimum factor of safety can be formulated as a non-linear programming problem with equality constraints only based on a yield criterion, a flow rule, boundary conditions, and an energy-work balance equation. Because of the non-linear property of the resulting optimization problems, a non-linear mathematical programming algorithm has to be employed. In this paper, the relations between the numbers of nodes, elements, interfaces, and subsequent unknowns and constraints in the approach have been derived. It can be shown that in the large-scale problems, the unknowns are subject to a highly sparse set of equality constraints. Because of the existence of non-linear equalities in the approach, this paper applies first time a special sequential quadratic programming (SQP) algorithm, feasible SQP (FSQP), to obtain solutions for such non-linear optimization problems. In FSQP algorithm, the non-linear equality constraints are turned into inequality constraints and the objective function is replaced by an exact penalty function which penalizes non-linear equality constraint violations only. Three numerical examples are presented to illustrate the potentialities and efficiencies of the FSQP algorithm in the slope stability analysis. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Clarification of regional and local in situ stresses using the compact conical-ended borehole overcoring technique and numerical analysis

    ISLAND ARC, Issue 3 2003
    Seong-Seung Kang
    Abstract Stress measurement is performed to estimate the states of in situ rock stress at the Torigata open-pit limestone mine in Japan using the compact conical-ended borehole overcoring (CCBO) technique. A set of back and forward analyses are then carried out to evaluate the states of regional and local in situ rock stresses and the mine-induced rock slope stability using a 3-D finite element model. The maximum horizontal local in situ rock stress measured by the CCBO technique acts in the northeast,southwest direction. The horizontal regional tectonic stresses obtained by the back analysis are in good agreement with those of the horizontal local in situ rock stress measured by the CCBO technique. However, the horizontal regional tectonic stress is more compressive than the horizontal local in situ rock stress. This is because the horizontal regional stress due to gravity is not considered in the back-analyzed horizontal regional tectonic stress, but it is included in the local in situ rock stress measured by the CCBO technique. The local stress obtained by the forward analysis, especially its horizontal components, is in good agreement with the horizontal local in situ rock stress measured by the CCBO technique, and the magnitude of the vertical normal stress increases more rapidly than those of the horizontal normal stresses with depth. As a result, the ratio of the horizontal normal stress to the vertical normal stress is largest at the nearest excavation level and decreases with depth. This means that the stress field within the mine-induced rock slope is affected by the horizontal components of the local in situ rock stress. [source]

    Towards ground truthing exploration in the central Arctic Ocean: a Cenozoic compaction history from the Lomonosov Ridge

    BASIN RESEARCH, Issue 2 2010
    M. O'Regan
    ABSTRACT The Integrated Ocean Drilling Program's Expedition 302, the Arctic Coring Expedition (ACEX), recovered the first Cenozoic sedimentary sequence from the central Arctic Ocean. ACEX provided ground truth for basin scale geophysical interpretations and for guiding future exploration targets in this largely unexplored ocean basin. Here, we present results from a series of consolidation tests used to characterize sediment compressibility and permeability and integrate these with high-resolution measurements of bulk density, porosity and shear strength to investigate the stress history and the nature of prominent lithostratigraphic and seismostratigraphic boundaries in the ACEX record. Despite moderate sedimentation rates (10,30 m Myr,1) and high permeability values (10,15,10,18 m2), consolidation and shear strength measurements both suggest an overall state of underconsolidation or overpressure. One-dimensional compaction modelling shows that to maintain such excess pore pressures, an in situ fluid source is required that exceeds the rate of fluid expulsion generated by mechanical compaction alone. Geochemical and sedimentological evidence is presented that identifies the Opal A,C/T transformation of biosiliceous rich sediments as a potential additional in situ fluid source. However, the combined rate of chemical and mechanical compaction remain too low to fully account for the observed pore pressure gradients, implying an additional diagenetic fluid source from within or below the recovered Cenozoic sediments from ACEX. Recognition of the Opal A,C/T reaction front in the ACEX record has broad reaching regional implications on slope stability and subsurface pressure evolution, and provides an important consideration for interpreting and correlating the spatially limited seismic data from the Arctic Ocean. [source]