1854
Proceedings of the 18t
h
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
existing pile to be instrumented to assess the integrity of
existing piles for reuse can also be discussed.
Paper 2971” New Sensing Technology and New
Applications in Geotechnical Engineering” by Wang, Ooi &
Gao from Hong Kong. The paper described that soils are
inherently a particulate medium, and relevant physical
principles behind the macro-scale engineering properties
originate from particle interactions. However, it is difficult in
general to conduct measurements which can monitor soil
particle movement and even characterize micromechanics
behind different soil behaviour. The paper presented two
examples of advancement of sensing technologies. The first is
on using the tactile pressure sensor (film-like sensor) to monitor
the evolution of contact normal forces among particles in aged
sand. The measurement reveals that the contact forces are
continuously redistributed during aging. This ultimately
strengthens the soil structure and therefore increases the
associated small-strain shear modulus. The second is on using
the miniature 3D Micro-Electro-Mechanical-Systems (MEMS)
accelerometer to characterize the soil movement in a laboratory
flow landslide. The MEMS sensors demonstrate promising
results in describing the rich features of local responses of soil
movement in the shear zone, e.g. liquefaction, deceleration,
contraction and dilation. Some comments on the paper: Are the
sensors insensitive to any other property likely to be
encountered in its application and to what extent the sensors
influence the measured property? Are the sensors designed to be
linear or linear to some simple mathematical function of the
measurement, typically logarithmic? What is the dynamic error
of MEMS accelerometer? A very relevant paper on application
of the small-strain theory on flow slides.
Paper 1965 “Monitoring earthwork foundations by fibre
optic sensors” by Artières from France. The paper presented
that strain in earthworks is now easier to measure by using fibre
optic sensing technologies combined with geotextile properties,
such as very good soil friction interface enhancing the transfer
of soil displacement to the sensors. More accurate
measurements can be obtained due to their smaller and less
intrusive size than those of the usual electro-mechanical strain
gages. They have high sensing sensitiveness below 0.01% on
strain measurement, but also temperature measurement with
0.1°C accuracy, that is combined with a high spatial resolution
in the range of 1 m or less and a good durability of the sensors
into soil. And they can be used to monitor either local
earthworks such as walls and slopes or long infrastructures of
several tenths of kilometers such as roads, railways and dikes,
all with the same accuracy. Several tenths of earthworks are
now monitored globally with this solution for more than 8 years
demonstrating its durability. The detection of cavities in the
foundation of a large polluted water storage basin was also
described. Some comments on the paper: Are the sensors
insensitive to any other property likely to be encountered in its
application and to what extent the sensors influence the
measured property? And are the sensors designed to be linear or
linear to some simple mathematical function of the
measurement, typically logarithmic? The paper was selected for
oral presentation on its relevancy in the application of sensor
technology in practical works.
1.2
Papers recommended for panel presentation
Paper 2253 “Development of Method for Evaluating and
Visualizing 3-dimensional Deformation of Earth Retaining Wall
for Excavation” by Matsumaru and Kojima from Japan. The
paper described a System to evaluate and visualize retaining
wall as three-dimensional curved surface. The validity was
confirmed by the simulation of the loading test on the model
wall and actual monitoring from the on-site measurement. It
proposed to conduct monitoring of retaining walls using this
analytical method and simple inclinometers. The paper
describes original research/application and would be interested
to most researchers.
Paper 2669 “Geotechnical protection of engineering
infrastructure objects in large cities under intense anthropogenic
impact and long term operation” by Perminov, Zentsov,
Perminov, Russia. This article describes more than 30-year
experience of scientific and technical support, design,
construction and reconstruction of water supply and sewage
facilities in St. Petersburg, Sochi, etc. It includes experience of
sinking of large diameter shaft/caisson and long term loadings
on tunnels in urban areas. Could do with a thorough proof
reading and some of the terms used are unfamiliar. It is
recommended for Panel presentation as it will be of interest to
those who would like to practice in Russia.
Paper 2535 “A geoenvironmental application of an
optimisation model” by Azimi, Merrifield, Gallagher & Smith
from UK. The paper summaries a network of monitoring wells
installed in and around a refinery in mid 1990s as part of a
research project aiming to investigate the impact of local
groundwater on corrosion of buried foundations and
underground storage facilities. A second research project was
started in 2000 to delineate the extent of the oil contamination
mound(s) beneath the refinery and devise appropriate remedial
measures. This paper presented an optimisation technique
which assisted with augmentation of the monitoring network,
thereby the cost-effective delineation of the oil mounds beneath
the refinery. An optimisation model, The Maximal Covering
Location Problem (MCLP), was modified and applied to find
the optimum number and locations of additional monitoring
wells to assist with the cost-effective delineation of the oil
contamination mound beneath the refinery.
It is recommended for panel presentation as it may provide
further discussions on the degree of confidence in selection of
the value of maximal service distance (S) in the order of 100m
without consideration of field, laboratory and theoretical
investigations.
Paper 2460 “Evaluation of diaphragm wall as-built data to
determine the risk of leakage for the Kruisplein car park
excavation in Rotterdam, The Netherlands” by Hannink &
Thumann from Netherlands. This paper should give the
geological profile of the site to let readers have a better
understanding of the ground conditions. Representative
pumping test results may be included to demonstrate the critical
or potential locations of leakage and the contingency measures
which shall be required. It is recommended for Panel
presentation.
Papers 3083 “Preventive maintenance of water retaining
structures based on fiber optic systems” by Fry, Courivaud,
Beck & Pinettes from France. The Pare described that EDF
develops the concept of preventive maintenance. It means
design, building and operation of an early warning monitoring
system (leakage and strains), plus model of interpretation and
portfolio of technical or legal alarm and interventions. In that
framework, EDF has been working since 1994 on the
development of the use of the distributed measurements with
fiber optic, to improve the monitoring of dykes and flood
embankments. The fiber optic technology provides a remote
control measurement of the distributed temperature and strain
every meter along the embankment. This new technology
strategically placed in the fill, allows to reinforce the hydraulic
and mechanical behavior monitoring, which is provided to date
by conventional instrumentation (leveling, piezometer,
discharge rate), with simultaneously a global and detailed
surveillance and an early warning system for extreme loadings
and crisis (floods, earthquakes, vandalism). It introduces the
principle of dikes monitoring using fiber optic and the
validation results of this technology from both trial test sites and
on EDF's real sites.
