The Mt. Gamalama Instability in Generating Landslides in Ternate Island, Indonesia

2020 ◽  
Author(s):  
Saaduddin Saaduddin ◽  
Jurgen Neuberg ◽  
Mark Thomas ◽  
Jon Hill
Keyword(s):  
Slope Stability ◽  
Limit Equilibrium ◽  
Stable Condition ◽  
Static Condition ◽  
Characteristic Parameter ◽  
Parameter Analysis ◽  
Limit Equilibrium Methods ◽  
A Value ◽  
South West ◽  
History Of

<p>Mt. Gamalama has a history of volcanic tsunamis that have occured in 1608 and 1840. Regarding its geomorphology, Mt. Gamalama has very steep flanks, and landslides entering the sea could be the potential mechanism of tsunami generation which could threaten the coastal population and submarine infrastructure in the vicinity of Mt. Gamalama.</p><p>The potential volumes and types of landslides are estimated by a study of the Mt. Gamalama instabilities using the Generalized Hoek-Brown failure criterion which is applied in<em> Slide2D</em> (Rocscience), a 2D slope stability program using limit equilibrium methods. This procedure will result in a so-called <em>Factor of Safety</em> or FoS which represents a value of the Mt. Gamalama slope stability level.</p><p>The critical FoS values ranging from 1.945 to 3.361 have been obtained for four sections i.e., north, south, west and east side of the Mt. Gamalama edifice and are considered in relatively stable condition. These values hold for a static condition only under the force of gravity and in the absence of any volcanic activities. The application of seismic coefficients of 0.103 and 0.658, magma pressure of 2-17 MPa, and various angles of a dyke intrusion decreases the Mt. Gamalama stability and might cause landslides. Based on posture parameter analysis of modeled landslides, the landslide volumes could reach 10<sup>6</sup> -10<sup>9</sup> m<sup>3</sup>. Furthermore, regarding the morphometric characteristic parameter analysis, the landslide mobility could enter the Molucca seaand generate tsunamis.</p><p>Keywords: Gamalama, volcanic instability, volcanic landlsides, volcanic tsuamis</p>

scholarly journals Slope stability analyses by circular failure chart and limit equilibrium methods: the inlet and outlet of diversion tunnel of Bolango Ulu Dam, Indonesia

2021 ◽  
Vol 325 ◽  
pp. 01015
Author(s):  
Alesandro Sejo Luden ◽  
I Gde Budi Indrawan ◽  
Dwikorita Karnawati
Keyword(s):  
Slope Stability ◽  
Limit Equilibrium ◽  
Stable Condition ◽  
Outlet Section ◽  
Inlet Section ◽  
Residual Soil ◽  
Diversion Tunnel ◽  
Stability Analyses ◽  
Limit Equilibrium Methods ◽  
Natural Slopes

The objective of this research is to evaluate the stability of the natural slopes at the inlet and outlet portals of the Bolangu Ulu diversion tunnel, Gorontalo. The natural slopes were considered stable, and therefore slope stability analyses were not carried out previously in the tunnel portal design. The slope stability analyses were carried out using the Circular Failure Chart (CFC) and Limit Equilibrium Methods (LEM). Input data for the slope stability analyses were obtained from field mapping and laboratory testing of soil and rock samples. The results show that the portal slopes consist of diorite and residual soil. Both stability analysis methods yield nearly the same results. The slope at the outlet section had the factor of safety (FOS) values of 1.29 and 1.30 based on the CFC method and LEM, respectively, indicating the slope in a stable condition. However, the slope at the inlet section had the FOS values of 1.01 and 1.07 based on the CFC method and LEM, respectively, indicating the slope in a critical condition. The results suggest that stabilization of the portal slopes, particularly the portal slope at the inlet section, is required to prevent slope failures under static and earthquake loads.

Some difficulties associated with the limit equilibrium method of slices

1983 ◽  
Vol 20 (4) ◽  
pp. 661-672 ◽  
Author(s):  
R. K. H. Ching ◽  
D. G. Fredlund
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Stability Limit ◽  
Limit Equilibrium Method ◽  
Soil Conditions ◽  
Side Force ◽  
Limit Equilibrium Methods ◽  
Equilibrium Method ◽  
The Stability

Several commonly encountered problems associated with the limit equilibrium methods of slices are discussed. These problems are primarily related to the assumptions used to render the inherently indeterminate analysis determinate. When these problems occur in the stability computations, unreasonable solutions are often obtained. It appears that problems occur mainly in situations where the assumption to render the analysis determinate seriously departs from realistic soil conditions. These problems should not, in general, discourage the use of the method of slices. Example problems are presented to illustrate these difficulties and suggestions are proposed to resolve these problems. Keywords: slope stability, limit equilibrium, method of slices, factor of safety, side force function.

scholarly journals Analysis of embankment slope stability: the comparison of finite element limit analysis with limit equilibrium methods

2019 ◽  
Vol 270 ◽  
pp. 02004
Author(s):  
Kongkit Yingchaloenkitkhajorn
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Limit Analysis ◽  
Limit Equilibrium ◽  
Slope Angle ◽  
Friction Angle ◽  
Volume Element ◽  
Stability Number ◽  
Limit Equilibrium Methods ◽  
Embankment Slope

This paper presented the analysis of embankment slope stability by considering the problem of embankment slope stability with special effects that it was filled with sand and was placed on purely cohesive clay. The finite element limit analysis of two-dimensional plane strain was employed to analyze the stability of this problem. The embankment slope height (H), the depth factors (d/H) and the embankment slope angle (β) for the finite element limit analysis of sand was modeled as a volume element with the properties of Mohr-Coulomb material in drained condition. And the clay was modeled as a volume element with the properties of Tresca material in undrained condition where the parameters were soil unit weight (γ), undrained shear strength (su) and friction angle (φ′). Parametric studies consisted of three dimensionless variables including depth factors (d/H), friction angle (φ′) and embankment slope angle (β). Results were summarized in the form of the dimensionless stability number (su/γH(FS)) and the design chart and application were presented. In addition, the comparison of the solution of stability number with the limit equilibrium methods and the failure mechanisms were also proposed in this paper.

The application of dynamic programming to slope stability analysis

2003 ◽  
Vol 40 (4) ◽  
pp. 830-847 ◽  
Author(s):  
Ha T.V Pham ◽  
Delwyn G Fredlund
Keyword(s):  
Dynamic Programming ◽  
Slope Stability ◽  
Stress Analysis ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Programming Method ◽  
Dynamic Programming Method ◽  
Critical Slip Surface ◽  
Limit Equilibrium Methods ◽  
Conventional Limit

The applicability of the dynamic programming method to two-dimensional slope stability analyses is studied. The critical slip surface is defined as the slip surface that yields the minimum value of an optimal function. The only assumption regarding the shape of the critical slip surface is that the surface is an assemblage of linear segments. Stresses acting along the critical slip surface are computed using a finite element stress analysis. Assumptions associated with limit equilibrium methods of slices related to the shape of the critical slip surface and the relationship between interslice forces are no longer required. A computer program named DYNPROG was developed based on the proposed analytical procedure, and numerous example problems have been analyzed. Results obtained when using DYNPROG were compared with those obtained when using several well-known limit equilibrium methods. The comparisons demonstrate that the dynamic programming method provides a superior solution when compared with conventional limit equilibrium methods. Analyses conducted also show that factors of safety computed when using the dynamic programming method are generally slightly lower than those computed using conventional limit equilibrium methods of slices; however, as Poisson's ratio approaches 0.5, the computed factors of safety from the dynamic programming method and the limit equilibrium method appear to become similar.Key words: dynamic programming, slope stability, stress analysis, optimization theory, limit equilibrium methods of slices.

scholarly journals Strain-dependent slope stability

2020 ◽  
Vol 15 (11) ◽  
pp. 3111-3119
Author(s):  
Kornelia Nitzsche ◽  
Ivo Herle
Keyword(s):  
Slope Stability ◽  
Failure Modes ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Shear Stresses ◽  
Safety Factors ◽  
Limit Equilibrium Methods ◽  
Hydraulic Conditions ◽  
Stress States ◽  
Strain Dependent

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.

Sign in / Sign up

Export Citation Format

Share Document