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.

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.

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.

Convergence aspect of limit equilibrium methods for slopes

1990 ◽  
Vol 27 (1) ◽  
pp. 145-151 ◽  
Author(s):  
R. N. Chowdhury ◽  
S. Zhang
Keyword(s):  
Factor Of Safety ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Solution Process ◽  
Iterative Solution ◽  
Friction Angle ◽  
Equilibrium Analysis ◽  
Negative Slope ◽  
Slip Surfaces ◽  
Geological Discontinuity

This note is concerned with the multiplicity of solutions for the factor of safety that may be obtained on the basis of the method of slices. Discontinuities in the function for the factor of safety are discussed and the reasons for false convergence in any iterative solution process are explored, with particular reference to the well-known Bishop simplified method (circular slip surfaces) and Janbu simplified or generalized method (slip surfaces of arbitrary shape). The note emphasizes that both the solution method and the method of searching for the critical slip surface must be considered in assessing the potential for numerical difficulties and false convergence. Direct search methods for optimization (e.g., the simplex reflection method) appear to be superior to the grid search or repeated trial methods in this respect. To avoid false convergence, the initially assumed value of factor of safety F0 should be greater than β1(=−tan α1 tan [Formula: see text]) where α1 and [Formula: see text] are respectively the base inclination and internal friction angle of the first slice near the toe of a slope, the slice with the largest negative reverse inclination. A value of F0 = 1 + β1, is recommended on the basis of experience. If there is no slice with a negative slope for any of the slip surfaces generated in the automatic, search process, then any positive value of F0 will lead to true convergence for F. It is necessary to emphasize that no slip surface needs to be rejected for computational reasons except for Sarma's methods and similarly no artificial changes need to be made to the value of [Formula: see text] except for Sarma's methods. Key words: slope stability, convergence, limit equilibrium, analysis, optimization, slip surfaces, geological discontinuity, simplex reflection technique.

Marine Site Investigations and BS 5930

1986 ◽  
Vol 2 (1) ◽  
pp. 163-166 ◽  
Author(s):  
P. G. Carter ◽  
R. M. Pirie ◽  
M. Sneddon
Keyword(s):  
Survey Methods ◽  
Site Investigation ◽  
Land Site ◽  
Site Investigations ◽  
Investigation Methods ◽  
Ground Investigation ◽  
Wide Range ◽  
Marine Site

AbstractMarine site investigations are reviewed briefly, in terms of suitable drilling platforms and craft for various conditions, requirements for permissions and service locations, marine ground investigation methods and marine survey methods including geophysical profiling.The wide range of marine site investigation methods is illustrated and the appreciable differences from land site investigation methods are noted. It is suggested that BS 5930 does not give sufficient guidance on marine site investigations and that this situation should be rectified.

Downslope movements at shallow depths related to cyclic pore-pressure changes

1993 ◽  
Vol 30 (3) ◽  
pp. 464-475 ◽  
Author(s):  
K.D. Eigenbrod
Keyword(s):  
Pore Water ◽  
Slip Surface ◽  
Pore Water Pressure ◽  
Limit Equilibrium ◽  
Water Pressure ◽  
Ground Surface ◽  
Soil Mass ◽  
Passive Resistance ◽  
Pressure Changes ◽  
Timber Piles

Slow, shallow ground movements in a slope near Yellowknife caused excessive tilting of timber piles that supported an engineering structure. To avoid damage to the structure, the pile foundations had to be replaced by rigid concrete piers that were designed to resist the forces of the moving soil mass. Downhill movements were rather slow and, during an initial inspection, were indicated only by soil that was pushed up against a series of piles on their uphill sides, while gaps had formed on their downhill sides. No open cracks or bulging was observed on the slope. A stability analysis indicated that the slope was not in a state of limit equilibrium. To obtain a better understanding of the creep movements in the slope and their effect on the rigid concrete piers, extensive instrumentation was carried out after the construction of the piers. This included slope indicators, piezometers, thermistors, and total-pressure cells against one of the concrete piers. In addition, a triaxial testing program was undertaken in which the effect of cyclic pore-water pressure changes on the long-term deformations of the shallow clay layer was investigated. From the data collected in the field and laboratory, it could be concluded that (i) tilting of the original timber piles was caused by downslope movements related to cyclic pore-water increases; (ii) the lateral soil movements increased almost linearly with depth from 2 m below the ground surface, with no indication of a slip surface; and (iii) the pressures exerted by the moving soil mass against the rigid concrete piers within the soil mass were equal to the passive resistance activated within the moving soil mass. Key words : soil creep, slope movements, soil pressures, pore-water pressures, freezing pressures, permafrost, cyclic loading.

Analysis of Ground Surface Displacements under the Influence of Repeated Mining Activities in the Zhezkazgan Area

2021 ◽  
Vol 57 (2) ◽  
pp. 184-189
Author(s):  
N. F. Nizametdinov ◽  
V. D. Baryshnikov ◽  
R. F. Nizametdinov ◽  
M. B. Igemberlina ◽  
H. Staňková ◽  
...  
Keyword(s):  
Ground Surface ◽  
Mining Activities ◽  
Surface Displacements

The extent of building and managing local contents in institutional repositories: a survey of tertiary institution libraries in Nigeria

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Godwin Oberhiri-Orumah ◽  
Ebikabowei Ebikabowei Baro
Keyword(s):  
Developing Countries ◽  
Site Investigation ◽  
Original Material ◽  
Colleges Of Education ◽  
Online Questionnaire ◽  
Tertiary Institution ◽  
Content Type ◽  
Tertiary Institutions ◽  
Institutional Repositories ◽  
Investigation Methods

Purpose The purpose of this study is to investigate the development of institutional repositories (IR) in tertiary institution libraries in Nigeria. Design/methodology/approach The study adopted a survey research method. Online questionnaire and IR site investigation methods were used to collect data from 25 university libraries in Nigeria. Findings The study revealed that only 25 (14.7%) universities out of the 170 universities in Nigeria have successfully developed IRs and registered their presence in OpenDOAR. Other tertiary institutions such as Polytechnics and Colleges of Education investigated in Nigeria are yet to develop IRs. Contents such as theses and dissertations, conference proceedings and journal articles ranked highest being the most popular contents in the various IRs. The results showed that the development of IR saves space in the library, increases readership, increases access to local contents, minimizes damage to the original material, facilitates the dissemination of scholarly research and assists in globalization of Nigerian research findings. The IRs site investigation revealed that only few IRs have clearly defined access policy, content policy, submission policy and digital preservation policy. The study identified challenges such as inadequate facilities, unstable internet connectivity, lack of fund, irregular power supply, challenge of collecting materials for the IR, lack of skilled ICT personnel, copyright issues and absence of IR policies. Practical implications The results from the study will provide important data and insight into the development of institutional repositories in tertiary institution libraries in Nigeria, and generate suggestions for University Librarians, College Librarians, Polytechnic Librarians, tertiary institutions management and policy makers for developing institutional repositories in Nigeria and other developing countries. Originality/value The study investigated IR development in tertiary institutions in Nigeria. The findings will inform other tertiary institutions in developing countries that the development of IR provides an opportunity for the visibility of local contents emanating from institutions and make them see the reason to embrace this laudable development.

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