Simulation of risk of progressive slope failure

1992 ◽  
Vol 29 (1) ◽  
pp. 94-102 ◽  
Author(s):  
R. N. Chowdhury
Keyword(s):  
Shear Strength ◽  
Slope Failure ◽  
Direct Evidence ◽  
Slip Surface ◽  
Progressive Failure ◽  
Residual Shear Strength ◽  
Slip Surfaces ◽  
Surface Measurements ◽  
Risk Simulation ◽  
Deterministic And Probabilistic Approaches

Understanding of progressive failure of slopes is of immense interest to geotechnical engineers and others concerned with the occurrence of landslides. One important aspect of research is the development of relevant analytical and numerical techniques. Both deterministic and probabilistic approaches can be used to study the development of progressive failure, provided valid geomechanics models form the basis of such studies. In this paper the risk of failure is simulated within a probabilistic framework. Of particular interest is the increase in the probability of failure, as overstress (and consequent localized failure) is considered to have actually occurred over an increasing proportion of a slip surface within the slope. The perception or interpretation of local failure is often based on observational data from surface measurements and subsurface instrumentation. Knowledge of spatial progression of failure may similarly be based on indirect and direct evidence. In the proposed simulation process the peak and residual shear strength of the slope material are regarded as one-dimensional random fields, and therefore spatial variability of each parameter is taken into consideration. Key words : analysis, clays, failure, shear strength, slopes, stability, landslides, probabilistic analysis, reliability analysis, progressive failure, slip surfaces, risk simulation, statistical analysis.

Analysis of Slope Failure Mechanisms Considering Micropile-Soil Interaction

2013 ◽  
Vol 535-536 ◽  
pp. 565-568 ◽  
Author(s):  
Hong Jian Liao ◽  
Cheng Lin Tian ◽  
Hang Zhou Li
Keyword(s):  
Large Scale ◽  
Slope Failure ◽  
Slip Surface ◽  
Loess Soil ◽  
Scale Model ◽  
Maximum Shear Strain ◽  
Loess Slope ◽  
Slip Surfaces ◽  
Large Scale Model ◽  
Stress And Deformation

A large scale model test was carried out in loess slope, in which the stress and deformation characteristics of slopes reinforced with different arrangements of micropiles were studied. The mechanism of the micropile-soil interaction and the reinforcement effect of micropiles in loess slope were analysed. Based on the scale of in-situ loess slope and the physical mechanics parameters of loess soil, a numerical model was established by using finite difference method. For a reasonable arrangement of micropiles in step-shaped slope, the critical slip surfaces were determined considering the influence of slope inclination, ratio of step height and loading position. The micropiles were arranged in the step-shaped slope based on the critical slip surface, and the relationship between the ultimate bearing capacity of slope and shear strength parameters of loess soil was studied. The maximum shear strain of micropile-soil and moment of micropiles were calculated, and then the mechanism of the micropile-soil interaction was analysed.

The growth of slip surfaces in the progressive failure of over-consolidated clay

1973 ◽  
Vol 332 (1591) ◽  
pp. 527-548 ◽  
Keyword(s):  
Shear Stress ◽  
Shear Band ◽  
Slip Surface ◽  
Progressive Failure ◽  
Soil Mechanics ◽  
Propagation Speed ◽  
Viscoelastic Deformation ◽  
Slip Surfaces ◽  
Local Strength ◽  
The Mean

In heavily over-consolidated clays there is a marked peak in the observed relation between shear stress and shear strain. As the strain increases, the stress falls from a peak to a much smaller residual stress. Slopes made from such a clay often fail progressively many years after construction. Sliding occurs on a concentrated slip surface, and it is found that the mean resolved shear stress on that surface is markedly less than the peak shear strength. Concepts from fracture mechanics, and in particular the J -integral, are used to derive conditions for the propagation of a concentrated shear band of this kind. The results indicate the presence of a strong size effect, which has important implications for the use of models in soil mechanics. An elastic analysis makes it possible to determine the size of the end zone in which the shear stress on the shear band falls to its residual value. An attempt is made to assess the possible sources of the time-dependence governing propagation speed of the shear band. They include pore-water diffusion to the dilating tip of the band (which governs the rate at which local strength reductions can occur), viscoelastic deformation of the clay (which allows a gradual build-up of strain concentration at the tip of the band), and the weathering break-down of diagenetic bonds.

The geometry of slip surfaces beneath landslides: predictions from surface measurements

1985 ◽  
Vol 22 (2) ◽  
pp. 234-238 ◽  
Author(s):  
M. Carter ◽  
S. P. Bentley
Keyword(s):  
Slip Surface ◽  
Surface Profile ◽  
Ground Surface ◽  
Feasibility Studies ◽  
Site Investigation ◽  
Model Studies ◽  
Slip Surfaces ◽  
Surface Displacements ◽  
Investigation Methods ◽  
Surface Measurements

A knowledge of the slip surface profile beneath a landslip is essential for stability analysis and for the design of remedial works. This note sets out to demonstrate the accuracy of a technique that utilizes the measurement of surface displacements to predict the position and shape of the slip surface. The proposed technique is tested in model studies of all major classes of landslip and is used on three large landslips for which corroboratory evidence of the position of the slip surface, located by traditional site investigation methods, is available. The results indicate that, from a knowledge of ground surface displacements alone, the depth of the slip surface can be confidently predicted to within 2% of the distance between ground stations. The usefulness of this technique for planning and costing-feasibility studies, site investigation programmes, and prospective remedial measures is also discussed.

Potential Slip Surfaces of Slope with Strength Parameters

2011 ◽  
Vol 243-249 ◽  
pp. 3315-3318 ◽  
Author(s):  
Hang Lin ◽  
Ping Cao
Keyword(s):  
Shear Strength ◽  
Numerical Analysis ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Friction Angle ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Slip Surfaces ◽  
Stability Of Slope ◽  
The Stability

The cohesion c and friction angle φ are the main strength parameters influencing the stability of slope. Any of them changes, the factor of safety of slope will change, but it has seldom been considered in the literature how the potential slip surface will change at the same time. In the present paper, the analytical deduction and numerical analysis are done to find out the effect of shear strength parameters c and φ to the distribution of potential slip surface. The study shows that, the potential slip surface is affected by the combination of c and φ, whose function is λ=c/(γhtanφ).

New methods for system reliability analysis of soil slopes

2011 ◽  
Vol 48 (7) ◽  
pp. 1138-1148 ◽  
Author(s):  
J. Zhang ◽  
L.M. Zhang ◽  
Wilson H. Tang
Keyword(s):  
Reliability Analysis ◽  
Failure Probability ◽  
System Reliability ◽  
Slope Failure ◽  
Slip Surface ◽  
System Failure ◽  
Critical Slip Surface ◽  
New Methods ◽  
Slip Surfaces ◽  
System Reliability Analysis

A slope may have many possible slip surfaces. As sliding along any slip surface can cause slope failure, the system failure probability of a slope is different from the probability of failure along an individual slip surface. In this paper, we first suggest an efficient method for evaluating the system failure probability of a slope that considers a large number of possible slip surfaces. To obtain more insights into the system failure probability of a slope, we also propose a method to identify a few representative slip surfaces most important for system reliability analysis among a large number of potential slip surfaces and to calculate the system failure probability based on these representative slip surfaces. An equation for estimating the bounds of system failure probability based on the failure probability of the most critical slip surface is also suggested. The system failure probability is governed by only a few representative slip surfaces. For a homogenous slope, the failure probability of the most critical slip surface is a good approximation of the system failure probability. For a slope in layered soils, the system failure probability can be significantly larger than the failure probability of the most critical slip surface.

scholarly journals Determination of Residual Shear Strength from Reversal Direct Shear test: Analysis and Recommendation

2020 ◽  
Vol 8 (5) ◽  
pp. 5053-5058
Keyword(s):  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Slope Failure ◽  
Failure Zone ◽  
Direct Shear ◽  
Residual Shear Strength ◽  
Test Analysis ◽  
Undisturbed Sample

Reversal Direct Shear test is used for the determination of residual shear strength of soil sample. This test was conducted on undisturbed and remolded sample of embankment slope of Pa Bon Dam, Thailand that had failed after operating for 10 years. The undisturbed sample was taken from the downstream slope (non-failure zone) while the remolded sample was taken from the upstream slope (failure zone). The results yielded identical values of residual strength parameters. On the basis of laboratory test, various recommendations are proposed for the conduction of this test in future.

Deterministic and probabilistic treatments of multiplanar pitwall failures at Himmetoglu (Turkey) coal mine

2001 ◽  
Vol 38 (4) ◽  
pp. 828-849 ◽  
Author(s):  
Ergün Tuncay ◽  
Resat Ulusay
Keyword(s):  
Shear Strength ◽  
Coal Mine ◽  
Slope Failure ◽  
Failure Modes ◽  
Probabilistic Approach ◽  
Back Analysis ◽  
The South ◽  
Bedding Planes ◽  
Geotechnical Investigations ◽  
Deterministic And Probabilistic Approaches

This paper describes the investigation of a large and progressive slope failure in the south sidewall of the Himmetoglu coal mine in northwest Turkey. A number of slope instabilities leading to interruptions in mining have been experienced at the mine. Geotechnical investigations consisted of structural mapping, observations of instabilities, review of detailed groundwater information, long-term monitoring of slope movement, and back-analysis of the various failure modes. Deterministic and probabilistic approaches based on the limiting-equilibrium method were employed to examine various slope profiles and excavation sequences for achieving better stability conditions. Analysis of the movement monitoring records and geotechnical information indicated that the failure of the south sidewall slope developed by a combination of sliding along the bedding planes in the hanging wall and faults in the mode of multiplanar sliding. The movement history and the results from the back-analysis of the failures revealed that the stability of the slope was highly sensitive to changes in the length of the lower part of the sliding surface, and the shear strength reduced to residual values along the discontinuity surfaces 8-10 m above the coal seam at the time of failure. The results of the analysis both from deterministic and probabilistic approaches suggest that an excavation sequence consisting of a number of stripping stages from the uppermost benches and advancing to the toe of the slope may provide the resistance to stabilize the overall slope. Simple and preliminary economic assessments based on the overburden costs in conjunction with the deterministic and probabilistic approaches are briefly discussed.Key words: back-analysis, deterministic approach, Himmetoglu coalfield, monitoring, multiplanar failure, probabilistic approach, shear strength, slope stability.

The Hepburn landslide: an interactive slope-stability and seepage analysis

1991 ◽  
Vol 28 (4) ◽  
pp. 556-573 ◽  
Author(s):  
G. A. Misfeldt ◽  
E. Karl Sauer ◽  
E. A. Christiansen
Keyword(s):  
Factor Of Safety ◽  
Slope Failure ◽  
Slip Surface ◽  
Friction Angle ◽  
Seepage Analysis ◽  
Continuous Processes ◽  
Valley Slope ◽  
Slip Surfaces ◽  
Artesian Aquifer ◽  
Saline Springs

Mechanisms of active landslides are continuous processes involving the dynamics of slope failure interacting with the groundwater regime. This process is simulated in phases by combining stability calculations interactively with a seepage analysis to determine the factor of safety for a dormant landslide near Hepburn, Saskatchewan. The landslide is a multiple retrogressive failure with two parallel slip surfaces at different elevations. The slip surfaces are in originally overconsolidated Cretaceous and Tertiary clays softened by shear from glaciation. An artesian aquifer is present at the base of the slip surface, causing saline springs at the base of the valley slope. A residual effective friction angle of 6.7° with zero cohesion was found to best characterize the shear strength of the clays in the failure zone. Potential nets and head profiles from the seepage analysis illustrate the strong influence of changing topography on the groundwater flow system. The present-day factor of safety for the dormant landslide was estimated to be 1.10. Key words: multiple retrogressive landslides, dormant landslide, seepage modelling, residual strength, artesian conditions, glacial drift, Cretaceous clays.

scholarly journals Landslide geometry and activity in Villa de la Independencia (Bolivia) revealed by InSAR and seismic noise measurements

Landslides ◽  
2021 ◽  
Author(s):  
Chuang Song ◽  
Chen Yu ◽  
Zhenhong Li ◽  
Veronica Pazzi ◽  
Matteo Del Soldato ◽  
...  
Keyword(s):  
Time Series ◽  
Seismic Noise ◽  
Slip Surface ◽  
Inversion Method ◽  
Subsurface Structures ◽  
Slip Surfaces ◽  
Landslide Volume ◽  
Noise Measurements ◽  
Landslide Body

AbstractInterferometric Synthetic Aperture Radar (InSAR) enables detailed investigation of surface landslide movements, but it cannot provide information about subsurface structures. In this work, InSAR measurements were integrated with seismic noise in situ measurements to analyse both the surface and subsurface characteristics of a complex slow-moving landslide exhibiting multiple failure surfaces. The landslide body involves a town of around 6000 inhabitants, Villa de la Independencia (Bolivia), where extensive damages to buildings have been observed. To investigate the spatial-temporal characteristics of the landslide motion, Sentinel-1 displacement time series from October 2014 to December 2019 were produced. A new geometric inversion method is proposed to determine the best-fit sliding direction and inclination of the landslide. Our results indicate that the landslide is featured by a compound movement where three different blocks slide. This is further evidenced by seismic noise measurements which identified that the different dynamic characteristics of the three sub-blocks were possibly due to the different properties of shallow and deep slip surfaces. Determination of the slip surface depths allows for estimating the overall landslide volume (9.18 · 107 m3). Furthermore, Sentinel-1 time series show that the landslide movements manifest substantial accelerations in early 2018 and 2019, coinciding with increased precipitations in the late rainy season which are identified as the most likely triggers of the observed accelerations. This study showcases  the potential of integrating InSAR and seismic noise techniques to understand the landslide mechanism from ground to subsurface.

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