2656
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
variability and the increase of reliability. SCCAP methodology
also provides the stopping criteria for boring on the basis of
statistical formulations.
Steenfelt and Schunk discussed the cavity remediation for
piles underneath a cable stayed bridge. The cavity feature was
pressure grouted and transfer of axial load across the cavity into
Limestone was facilitated by insertion of grouted steel
reinforcement assemblies. The success of the remedial measures
was proven by carrying out an O-cell load test on the pile
positioned over the maximum recorded depth of the cavity.
Szep and Ray predicted that soil – structure interaction
could be better modelled using three dimensional geotechnical
finite element packages where true soil – structure could be
analyzed. The laterally loaded pile was analyzed using three
numerical methods like (1) AXIS 10VM which is the
fundamental structural design tool in Hungary, (2) GE04 and
GE05 which are popular geotechnical codes and (3) PLAXIS
and MIDAS GTS, which are 2D and 3D geotechnical finite
element packages for ensuring realistic modelling of soil –
structure interaction. Authors also used an optimization
technique for translating the pile head displacements and
rotations computed using finite element analyses to a small
number of elasto – plastic subgrade springs, which could be
used in various structural and geotechnical design software.
Teparaksa carried out damage assessment of the Bank of
Thailand head office by means of finite element method for
predicting its influence on the Tewavej Palace and
Bangkhunphrom Palace with simulation of basement
construction. The top down construction method was selected
for basement construction and complete set of instrumentation
was installed at the palaces, diaphragm wall and ground surface
for monitoring the field performance during and after basement
construction. The predicted wall movement obtained using
finite element analysis agreed well with the field performance,
and construction of basement was completed without affecting
the stability of the palaces
Ter – Martirosyan et al. proposed a rheological equation
based on modification of Maxwell rheological model to explain
the shear deformations in partial saturated hardening – softening
clay soil. Authors explained creep, relaxation and kinematic
shear including decaying, stable and progressive creep,
depending on shear stress intensity by using that proposed
equation. Authors showed that in constant loading case that
proposed equation described decaying, non-decaying and
progressing soil creep as well as stress and shear strain
relaxation processes in kinematic loading mode.
Tomisawa and Miura performed large-scale model
experiments to suggest a design verification method for pile
foundations combined with solidified improved columns with
following suggestions. Specifications for solidified columns are
related to ground conditions and the improvement depth
depends on characteristic pile length 1/β. The design horizontal
subgrade reaction P
HU
should be smaller than the passive earth
pressure of composite ground for inner stability and column
soundness. The allowable horizontal pile displacement in
normal conditions and during storms and Level-1 earthquakes
should be reduced to 0.5% of the pile diameter instead of 1%
(or 15 mm) for natural ground.
Tsuha et al. conducted experiments for determining the
influence of soil characteristics and configuration of helical
blades on the uplift capacity of multi – helix anchors. The
experiments included centrifuge tests on dry Fontainebleau sand
and tension load tests executed out in a tropical soil at Sao
Carlos in Brazil. The authors inferred that the efficiency of the
second helix of helical anchors embedded in sand decreased
with an increase in relative density of the sand and diameter of
the helix. Further it was also found that uplift capacity of triple
helix anchor with tapered helices were superior compared to
those with cylindrical helices.
Van Tol et al. presented the results of a study of concealed
safety factors by performing centrifuge tests on single pile and
group piles. For studying the time effect authors loaded single
pile in centrifuge test at 1, 10, 100,1000 minutes after
installation and for pile group also were followed the same
pattern and the centrifuge test was continued to operate from the
start of installation until the final load test. Authors showed that
the quantification of the effect and the determination of the
impact of load variations and recommended to continue with
research into pile group effects of displacement piles.
Wang et al. presented the aspects of design and construction
of super-long bored pile foundation together with a brief
description of bearing behaviors of super-long bored piles. Deep
buried firm soils are usually selected as the bearing stratum. The
authors suggests that the application of the double steel sleeves,
design of the pile top, construction and measurement
requirements are essential to the design of the field load test.
Calculation should consider the synergism of the superstructure,
soils and pile foundation. Inspection and controlling standards
of super-long bored piles are stricter than those of ordinary
piles.
Wong presented the results of two case studies on rock
socketed pile design and pile load testing in Sydney region of
Australia, in one site underlain by medium to high strength
shale, dynamic pile load testing was carried out, and on another
site underlain by high strength sandstone, Osterberg Cell (O-
Cell) testing was carried out to validate the designs. Author
concluded that better understanding of load-deformation
characteristics of pile foundations would lead to more cost-
effective designs.
Yanjing et al. proposed new methods for calculating
rebound and recompression deformations by analyzing the data
from the consolidation-rebound-recompression test of in-situ
soil, bearing test, model experiment and field measurement test,
which were based on the stress history of ground soil, loading
and unloading conditions. Authors established a mathematical
relation between rebound and recompression deformation. Form
the analysis authors concluded that;
1. The progress of rebound deformation exhibits three – phase’s
characteristics, and the critical unloading ratio was used to
determine the calculating depth of rebound deformation.
2. The recompression deformation was larger than rebound one
and the increase proportion vary with different kinds of soil.
3. The recompression deformation of foundation soil was
computed as two-phase mode.
Zaghouani et al. described some difficulties related to the
execution of large diameter deep piles in soft soils during the
construction of the bridge "Rades-La-Goulette" in Tunisia.
First, drilling piles of 2-m diameter up to 100-m depth in soft
clay met various problems that increased seriously the time
previously expected. That induced the horizontal displacement
of the borehole's wall toward its centre. Displacement was first
estimated using finite element modeling. Calculations show that
this problem would modify only the stress related to the lateral
friction but not that at the pile's toe. Second, difficulties related
to the concreting phase were also described. Some faults have
been detected along the piles by sonic inspections. The paper
describes the techniques adopted to repair these faults.
Zhang et al. reported the results of axial static load tests of
both full-scale instrumented pile groups and single piles. The
single pile settlement was found smaller than the corresponding
pile group settlement at the same average load per pile when the
load was relatively large. Group effect was more pronounced
for piles with smaller L/B ratios, and the impact of the pile
spacing is greater than that of the pile length. The load at the top
of the corner piles was observed to be the largest, followed by
side piles and then center piles.
