2143
Technical Committee 208 /
Comité technique 208
Saha
develops a global population-based search procedure
(APMA) and applies this to a classic slope-stability problem as
originally defined by Spencer (1967). It does not require
problem-specific knowledge in searching the critical slip-
surface of a soil slope but rather is a heuristic technique based
on the ‘generate-and-test’ strategy. The results show that a
lower factor of safety may be obtained with this technique than
is found by Methods-of-Slices that are commonly used.
Bogomolov et al.
suggest a method for calculating the
stability of a loaded slope, based on the combined use of the
finite element method, complex function theory and the
principle of virtual displacements, as formalized in a computer
program by the authors. The method ensures that a minimal
condition of the factor of safety K value at each point is
obtained without simplifying assumptions.
Nonoyama et al
. apply the SPH (Smoothed Particle
Hydrodynamics) method to a series of slope stability problems.
This numerical method, in which continuum-based constitutive
relations are input, can handle large deformation problems
because it is based on a free mesh system. This means it has the
potential to describe the deformation of geomaterials from the
initial state to subsequent large deformation and can be used to
estimate deformation and failure conditions simultaneously.
Using two example constitutive models, the authors present
analysis of both simple slopes and those with countermeasures
(piles) included and compare results to those obtained by the
Fellenius method.
In their extremely practical contribution,
Yeh et al.
introduce
the currently most adopted ground anchoring inspection system
used in Taiwan for anchoring slopes. The paper also proposes a
new method of ground anchoring assessment, in order to
establish a standardized quantitative analysis procedure for
professional reference. They find that four categories of
assessment should be made: inspecting the exterior of the
anchor, the anchor head, an endoscopy inspection and
conducting lift-off tests. They also examine the most common
shortcomings of anchor installation and suggest remedies.
Bozo and Allkja
present a study on the cuttings constructed
for the Vlora road in Albania. A description of the geological
setting of the site and of the rock and soil profiles is provided.
Using in situ and laboratory tests they have determined the type
of cuts and their geometrical forms in a manner designed to
protect both the environment and the stability of slopes.
Correlations between in situ test results and soil types are given
as well as classification data and strength data for the soils
encountered. They have also carried out some classifications of
cuts for the road taking into account the conditions of the
terrain.
The paper by
Lo and Lam
highlights some key lessons learnt
and observations made from selected landslide investigations by
the Geotechnical Engineering Office (GEO) of the of the Civil
Engineering and Development Department (CEDD) of Hong
Kong. On average, about 300 landslides are reported to GEO in
Hong Kong each year. The paper discusses the use of robust
stabilization measures for cut slopes, improved rock slope
engineering practices, enhanced practices in the monitoring and
maintenance of water-carrying services affecting slopes and
improvement to drainage detailing.
Du et al.
propose a quantitative model for estimating the
vulnerability of elements at risk from impact by a slope failure,
where vulnerability is defined as a function of landslide
intensity and of susceptibility of the element. A conceptual
framework is described for the model, and commentary
provided on parametric inputs to it, together with suggested
values for those parameters. The authors acknowledge the
limitations of the model in its current form, which arise from a
need to calibrate some of the input parameters.
Lacasse et al.
summarize the findings of a European
Commission project, SafeLand and its related ‘toolbox’ that is
web-based, which includes nearly 75 mitigation measures for
different types of landslide. Features of the toolbox are
described, which extend to estimates of cost-benefit factors and
likely effectiveness, all of which are predicated on a ranking of
the most appropriate mitigation measures. In this regard, the
toolbox takes the form of a decision-support tool.
8 SUMMARY REMARKS
In engineering, like many other subjects of professional
practice, it is important that the state-of-the-art continue to
inform the state-of-the-practice. In reality, the state-of-the-
practice involves risk management, whether it is done implicitly
or explicitly. It is by developing new knowledge, else refining
existing knowledge, that the findings of research enable
improved decision-making in the face of risk and uncertainty. A
total of 37 papers were submitted to the conference on the topic
of slope stability in engineering practice.
Although they are broad-ranging in subject matter, they are
unified by a common thematic objective of better understanding
the spatial and temporal variation of demand and capacity at the
point of slope instability, together with the magnitude and likely
run-out or travel distance of the ensuing event. In many respects
the findings of these studies are a timely reminder of the
observations of Karl Terzaghi that “In soil mechanics the
accuracy of computed results never exceeds that of a crude
estimate, and the principal function of theory consists in
teaching us what and how to observe in the field” (Goodman,
1999).
9 REFERENCES (TNR 8)
Chau K.T. 2005. General Report for Technical Session 4a: Slope
stability and landslides.
Proceedings of
16
th
International
Conference on Soil Mechanics and Geotechnical Engineering
,
Osaka, Japan.
Fannin R.J. and Bowman E.T. 2010. Debris flows—entrainment,
deposition and travel distance.
Proceedings of 11
th
IAEG Congress:
Geologically Active
, 5-8 Sept 2010, Auckland, New Zealand
Goodman, R.E. (1999). Karl Terzaghi: the engineer as artist. ASCE
Press, Reston, VA, USA, 340p.
Lin C.W., Shieh C. L., Yuan B. D., Shieh Y. C., Liu S. H. and Lee S. Y.
2004. Impact of Chi-Chi earthquake on the occurrence of landslides
and debris flows: example from the Chenyulan River watershed,
Nantou, Taiwan.
Engineering Geology
, 71, 49-61
Petley D. 2012. Landslides and engineered slopes: Protecting society
through improved understanding.
Proceedings of 11th International
& 2nd North American Symposium on Landslides
, 3-8 June 2012,
Banff, Canada.
Rose N.D and Hungr O. 2007. Forecasting potential rock slope failure
in open pit mines using the inverse-velocity method.
International
Journal of Rock Mechanics & Mining Sciences
, Vol. 44, 308-320.
Tatarniuk, C.M. and Bowman, E.T. (2012) Case Study of a Road
Embankment Failure Mitigated Using Deep Soil Mixing.
4th
International Conference on Grouting and Deep Mixing (ICOG)
,
16-18 Feb 2012.New Orleans, LA, USA:
10 PAPERS IN THE TECHNICAL SESSION
.Bogomolov A.N., Ushakov A.N. and Bogomolova O.A. Calculation of
slopes stability based on the energy approach.
Bozo L. and Allkja S. Preservation of slope stability along the bypass
Vlora.
Buscarnera G. and Whittle A.J. Model prediction of flow slide
triggering in shallow sandy slopes.
Cepeda J., Quan Luna B. and Nadim F. Assessment of landslide run-out
by Monte Carlo simulations.
Chang M. and Huang R. The challenge of the slope failure problem and
its remedial considerations at Mileage 39Km, Mt. Ali Road,
Taiwan.
Choi C.E., Ng C.W.W., Kwan J.S.H., Shiu H.Y.K., Ho K.K.S. and Koo
R.C.H. Downstream frontal velocity reduction resulting from
baffles.
Cohen-Waeber J., Sitar N. and Bürgmann R. GPS instrumentation and
remote sensing study of slow moving landslides in the eastern San
Francisco Bay hills, California, USA.
