Plaxis bulletin 37 2015

Title
Ed
Issue 37 / Spring 2015
Plaxis Bulletin
PLAXIS 3D analysis of the Groninger Forum
Evaluation of the up and down movements of the Vlaketunnel
with cyclic analysis using PLAXIS 2D
Pavement service life prediction and inverse analysis with PLAXIS 3D

Table of contents
Page4Page6Page10
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Erwin Beernink
Martin de Kant
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»The Plaxis Bulletin is the combined
magazine of Plaxis bv and the Plaxis users
association (NL). The bulletin focuses on the use
of the finite element method in geotechnical
engineering practise and includes articles on the
practical application of the PLAXIS programs,
case studies and backgrounds on the models
implemented in PLAXIS.
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Editorial03
04 New developments
Evaluation of the up and
down movements of the
Vlaketunnel with cyclic
analysis using PLAXIS 2D
10
PLAXIS 3D analysis of
the Groninger Forum
06
PLAXIS Expert Services
helped SETEC with complex
modelling issues
05
Pavement service
life prediction and inverse
analysis with PLAXIS 3D
14
Recent activities18
Upcoming events20
Page18

www.plaxis.com l Spring issue 2015 l Plaxis Bulletin 3
»We proudly present to you the spring 2015
edition of the Plaxis bulletin, including
three new interesting user articles. The release
of PLAXIS 2D 2015 and 2D Thermal module has
been made available, and most of our users have
already adopted the new version. Currently, we are
working hard to deliver the PLAXIS 3D Anniversary
Edition, containing several interesting additions in
the field of tunnelling, off-shore applications and
geomechanics.
The new developments column focuses on the
features that PLAXIS has implemented recently
and will be implementing with regard to Dynamics,
a very present-day topic in the Netherlands. We
also touch upon our progression in the field of
tunnelling and rock mechanics, presenting a new
material model for Shotcrete.
The first user’s contribution presents work on
PLAXIS 3D analysis of the Groninger Forum.
The project comprises a 45 meter high building
with two basements. The authors investigated the
new possibilities, that the staged construction
mode available in PLAXIS 3D gives in comparison
to their initial design in PLAXIS 3D Foundation.
It also discusses the differences between
predicted and measured settlements based on
their new approach and some suggested actions
dealing with large models and some other
modelling challenges.
In the second user’s article, the up and down
movements of the Vlaketunnel with cyclic analysis
are evaluated using PLAXIS 2D. The project was
performed as an MSc project, in the framework of
Infraquest, a research project which investigates
the sustainability of immersed tunnels in the
Netherlands. The article hypothesizes on a
possible cause of movements of the submerged
tunnel and proceeds with PLAXIS 2D modelling to
investigate the validity of the hypothesis.
Other proposed mechanisms are discussed as
well, based on the numerical results of several
model variations.
The third user’s article discusses a pavement
service life prediction and inverse analysis with
PLAXIS 3D. The author proposes certain workflows
incorporating both PLAXIS 3D and Matlab, to
perform two separate tasks. In one case, an
automated loading analysis to predict the level
of damage at the end of 30 years is done, where
PLAXIS calculates stresses and these stresses
are used in Matlab to assess the damage via an
empirical relationship, resulting in a new stiffness
for the pavement. This new stiffness is fed into
a PLAXIS 3D log file to run the next time step of
the full analysis and so on. In the second case,
the interactivity between PLAXIS 3D’s log file
and Matlab is used to back-calculate stiffness
parameters based on measurements of a three
dimensional deflection bowl.
For the PLAXIS Expert Services update, we
review a tailor made in-house training that Plaxis
provided to SETEC to get them up to speed
on modelling the construction of Evolutionary
Power Reactors, which was later supplemented
by ongoing advanced analysis support by PLAXIS
Expert Services staff.
In our recent activities section, some of the events
that our Asiapac and Americas offices organized
or participated in are discussed. We talk about the
activities of the Plaxis headquarters and about the
report of the Expedition Masai team which was
sponsored by Plaxis.
For our worldwide presence on events or hosted
courses, we refer you to the upcoming events
listed on the backside of the Plaxis Bulletin.
We trust that we have provided another issue with
engaging content for our readers and we look
forward to receiving your comments on the spring
2015 edition of the Plaxis Bulletin.
The Editors
Editorial

4 Plaxis Bulletin l Spring issue 2015 l www.plaxis.com
for tunnelling in rock as well as for dynamic
earthquake analysis. Please contact our sales
department to obtain the new shotcrete model
or one of the aforementioned user-defined soil
models + documentation. It is free of charge for
PLAXIS VIP users. We are looking forward to hear
about your experiences with these new models.
References
• Galavi G, Petalas A, Brinkgreve RBJ (2013).
Finite element modelling of seismic liquefaction
in soils. Geotechnial engineering journal of the
SEAGS & AGSSEA, 44(3), 55-64.
• Schädlich B, Schweiger HF (2014a).
Shotcrete model – Implementation, validation
and application of the shotcrete model.
Plaxis internal report. Computational
Geotechnics Group, Graz University of
Technology.
• Schädlich B, Schweiger HF (2014b).
A new constitutive model for shotcrete.
Proc. Numerical Methods in Geotechnical
Engineering (eds. Hicks, Brinkgreve, Rohe).
Taylor & Francis Group, London, 103-108.
New Developments
»Engineering consultants and research
institutes are investigating the effects
of earthquakes on buildings, industry and
infrastructure in the province of Groningen.
Many of them are using PLAXIS in their analyses.
In this respect, it worth mentioning the facilities
that PLAXIS has implemented in the past decade
for geotechnical earthquake engineering and
liquefaction analysis:
• Input motion in combination with rigid base or
compliant base boundaries
• Viscous (absorbing) boundaries, tied degrees-
of-freedom (for site response analysis) and free-
field boundaries (for earthquake analysis)
• Hysteretic damping in HSsmall and Generalised
Hardening Soil model (latter available as user-
defined soil model)
• Rayleigh damping
• Cyclic loading and liquefaction in UBC3D-PLM
model (available as user-defined soil model)
• PSA spectrum and Amplification curves
• Consistent mass matrix (more accurate dynamic
results; less dispersion)
More details about these facilities can be found in
a paper by Galavi et al. (2013). Validation reports
and documents on the practical use of PLAXIS
for site response and liquefaction analysis can be
found in the Plaxis Knowledge Base. For those who
are new in the field of geotechnical earthquake
engineering, it is good to know that we provide
support, short courses and in-house trainings with
our team of specialists. Besides the ‘excitement’
related to dynamic analysis, there are other new
developments worth mentioning.
One year ago, I already wrote about PLAXIS’
facilities for rock engineering and tunnelling.
Meanwhile, we have developed additional features
to enhance the modelling and analysis of tunnels
in rock. The upcoming release of PLAXIS 3D AE
will have a new tunnel designer with enhanced
features to create NATM-type tunnels, including
internal sections, loads and lining features.
Tunnel contours can be easily extruded along a
path before inserting them in the full geometry.
Tunnel shapes are now composed of full
parametric objects, providing a more accurate and
robust description of the tunnel geometry, which
also improves the meshing process.
In addition, with the release of PLAXIS 2D 2015 last
February, a new constitutive model for shotcrete
has become available as a user-defined model.
This model enables cutting-edge design of
sprayed concrete linings by considering the
following features of shotcrete (see also Schädlich
& Schweiger, 2014):
• Time-dependent stiffness and strength (from
freshly sprayed to matured shotcrete)
• Well-defined failure criterion for tension,
compression and shear
• Strain hardening and softening (with regularisation)
• Creep behaviour
• Shrinkage
The new ‘structural forces in volumes’ tool (available
in PLAXIS 2D) allows for the automatic integration
of stresses into structural forces in a tunnel lining
modelled by means of the new shotcrete model.
As you can see, PLAXIS is well-equipped nowadays
The north of The Netherlands (Groningen) is suffering from earthquakes. Not at the Kobe scale, but still very worrying for the
people living there. And since the earthquakes are induced by gasexploration, which generates quite some income for the
Dutch government, it has become a political issue.
Ronald Brinkgreve, Plaxis bv

»The complexity of the geological context
(general inclination of the soil strata towards the
North, anisotropy of the deformation moduli) leads to
intensive PLAXIS 3D modelling work in order to:
• Justify the structural strength of the gallery
• Optimize the geometry of the concrete mass
around it
• Define the optimal contact conditions to be
guaranteed between the mass concrete
and the gallery
PLAXIS Expert Services team has helped SETEC
to achieve their business objectives through
accelerated implementation and use of PLAXIS 3D
most advanced features. An assistance has been
provided in the operation of PLAXIS 3D software
applications aiming at:
• Providing better use and insight into the applica-
tion of the PLAXIS 3D software product
• Helping SETEC at being more productive and
competitive with respect to FE modelling work
now but also for future projects
This collaboration consisted in:
Customized trainings
PLAXIS Expert Services team has created two sets
of customized training material based on SETEC
specific requirements. With a custom training
session, SETEC has also tailored the agenda to cover
the information that will benefit its team the most.
Model examples that include their typical
geometries, materials and design procedures has
also been elaborated.
In the framework of PLAXIS Expert Services SETEC has been assisted in their simulation work in order to further improve their
own capabilities with highly complex modelling issues as being regularly encountered with the EPR UK project.
In the context of the construction of the British EPRs (Evolutionary Power Reactor), SETEC has been instructed with the design
of the prestressing gallery under the plant at Hinkley point.
E. Cazes - F.Cuira, SETEC, France
PLAXIS Expert Services
helped SETEC with complex modelling issues
Analysis support
The PLAXIS Expert Services staff was available to
support advanced analysis troubleshooting for a
wide range of problematic. Short-term support
services have been delivered in a timely manner in
the filed of meshing optimization process, geometry
import, very large number of objects handling.
of activity, which foster team responsibility and
motivation, as well as allowing for direct contact
with clients
• Strategic business units make it possible to
activate and coordinate the expert knowledge
within the various companies in the group to
ensure the success of cross-functional projects.
"We were very pleased with the very personalized support of the PLAXIS Expert
Services Team as well as their involvement with respect to the modeling choices
and most relevant simplifications to introduce.”
F. Cuira, Technical Director of Terrasol
About SETEC
SETEC currently has over 2400 employees in more
than 40 companies in France and abroad.
The SETEC group has two levels of organisation
which are the key to its originality and
effectiveness:
• Numerous relatively small companies,
specialising in a particular profession or area
The units also accommodate the discussions
and innovation work required to achieve
constant renewal of core business
On the international front, SETEC has set up sites
in Europe, Africa and America, wherever its
projects take it.

The west side comprises only Loam and sand
layers. The east side contains in addition a
12-meter-thick heavily overconsolidated clay
layer (OCR = 2 to 3), known in the Netherlands
as Potklei
• The phreatic groundwater level on the west side
is 2 m higher than on the east side
• Monumental buildings are present very close to
the excavation. The most vulnerable dates from
the year 1130 AC and is situated at the corner of
the excavation
• At the final design, the diaphragm wall on the
west side is circular shaped, while on the east
side it is rectangular
The first design was made in 2008, with PLAXIS 3D
Foundation. With this program it was only possible
to work with horizontal workplanes.
The inclining surrounding terrain was therefore
schematized by several small vertical steps, see
Figure 2. With this 3D model it became clear that
the deformations around the building pit are not
equal everywhere. Especially at the corners of the
excavation pit, the deformations are much smaller.
A second, high positioned, temporary strut was
added, to decrease the deformations furthermore.
Also the water level inside the building pit was
increased during excavation under water. With
these measures the risk for damages became
acceptably low.
With the release of the program “PLAXIS 3D”
a more detailed schematization of the different
building stages and the addition and removal of
strut tubes became possible.
»The deep excavation required to realize
the car park, is designed by ABT (Adviseurs
in Bouwtechniek). Diaphragm walls will be the
retaining system for the excavation and will be
supported horizontally by two layers of steel struts
(one at 1.5m and the other at 4.5m depth) and an
underwater concrete slab. Tubex Grout Injection
Piles (screwed piles with lost tube, lost pile tip and
a grout injection) and Gewi anchors avoid uplift
failure of the concrete slab. The excavation pit is
completely surrounded by adjoining properties,
which are within short distances of at least
2.5 m up to 12.5 m. These adjacencies are mainly
established on shallow foundation; a single
extension is founded on piles.
Besides the complexity in the stratigraphy (see
Table 1), there is also a geometrical asymmetry in
the plan view of the excavation. On the west side,
it comprises a semi-circle with a diameter of about
36 m. The east side is roughly a rectangle with
43 m in width and 105 m in length. This sums
a total perimeter of 267 m. The bottom of the
excavation is located 18 m below the surface.
Project challenges
There are several reasons to use a three-
dimensional finite element program to design the
deep excavation:
• On the west side the surface level is
approximately 2.5 to 3.0 m higher than on the
east side
• There is a significant difference in soil
stratigraphy between the two sides of the
excavation (see Table 1)
The Groninger Forum will be constructed in the center of Groningen city, the Netherlands. The building is commissioned by
the Groningen municipality. This 45-m-height and eccentric-styled cultural center will include a library, museums, cinemas,
restaurants and bars. Two basements complete the structure: a five-storey car park (suitable for 390 cars) and a one-storey
bicycle parking (suitable for 1,500 bicyles). The car park is located exactly underneath the main structure, whereas the bicycle
parking keeps a horizontal distance from it. Figure 1 shows a cross-section of the building and the two basements.
M.C.W. Kimenai MSc, senior geotechnical specialist, ABT
Figure 1: Cross section of “Groninger Forum”

Once the deep struts are laid, more deformation
at the East is prevented. Hence, deformations
only occur in the vicinity of where the slots are
excavated at that time. The vertical deformation
of the adjacent structures walk along with the
excavation of trenches and laying of the struts
(Figure 4). From this feasibility study it can be
concluded that the deformations under the
nearby adjacent buildings (if the ESBM with a
Stage construction possibilities
The initial idea of the construction sequence
considered that the upper struts are installed
before installing the lower ones. The procedure
was to remove the upper strut and then place it
back a few meters lower at the lower frame.
This had to be repeated for each of the struts,
having at the end all the lower struts in place and
all the upper struts removed. This method was
partly inspired by the traditional way of calculating
with two-dimensional programs.
The second idea was to install only 3 or 4 (at a total
of 15) of the upper struts and then advance with
the first of the lower struts. However, this approach
had a practical constraint: a mobile crane can only
lift the 40-ton strut at close range.
To overcome this limitation, the following
procedure is developed. Only the minimum
excavation necessary to install a single strut
is made. After the installation, the mentioned
excavation is backfilled and only then the
complete procedure is repeated for the next strut.
This stage construction procedure is hereafter
called the ESBM (which stands for local Excavation
– Strut installation – Backfilling Method).
It should be noted that this approach results in a
considerable amount of earthworks, but also in a
significant reduction of the excavated volume at a
given time. The latter remark means that the soil
deformations during the installation of the struts
are reduced. Hence, there is the possibility that
two layers of struts are not necessary anymore.
At least in theory.
ESBM with a single layer of struts
A feasibility study was started considering only
the use of the deep struts (i.e. the lower struts).
To this end, a PLAXIS 3D model was made, in
which all sub-phases for the laying of the several
tubes have been schematized step by step.
A number of oblique surfaces were added to
the 3D mesh, making it possible to input the
aforementioned local excavations inside the main
excavation area. Figure 3 shows the volumes
representing the local excavations.
The excavation-installation-backfill procedure is
performed for each strut from East to West until
all of them are in place. The remaining soil in the
western part of the main excavation prevents
deformations of nearby adjacent structures.
Layers West-side East-side
Surfacelevel NAP + 7,3 m NAP +4,3 m
Toplayer (sand, clay, debris) from +7,3 m to +3,0 m from +4,3 m to +0,0 m
Loam from +3,0 m to -6,0 m from +0,0 m to -6,0 m
"Potklei" - from -6,0 m to -18,0 m
Sand, stiff from -6,0 m to -40 m from -18,0 m to -40 m
Max depth site investigation -40 m
Table 1: Soil stratigraphy
Figure 2: PLAXIS 3D foundation model with small vertical steps Figure 3: Extra surfaces in the 3D mesh

Modelling challenges
The diaphragm walls are not modelled with
volume elements but with plate elements. For the
struts, beam elements and node-to-node anchors
are used. The surrounding soil is modelled as
a Hardening Soil (HS) material and to be fully
drained (the latter choice is justified since the goal
is to compute deformations). Table 2 presents the
main soil parameters. The underwater concrete
slab is modelled by volume elements with a
surface load on top to compensate the upward
water pressures (in reality this compensation will
be provided by the piles and anchors that are
excluded in the simulation).
single layer of struts is performed) are significantly
lower than when excavating the whole area until
the lower struts level at once. Nevertheless, since
the deformation levels were in the order of the
allowed deformations, it was finally decided not to
discard the use of the temporary upper struts.
Photo 1 shows the required soil excavation for the
placing of the different tubes in the upper and
lower layer of struts. Figure 5 shows the detailed
modelling in PLAXIS 3D in the final calculation.
Figure 6 shows the complete model, which can
be compared with the aerial picture of the real
situation in Photo 2.
All the extra oblique surfaces resulted in a mesh
with an important number of elements: more
than 500.000. The calculation of the intersections
between the soil stratigraphy and the structures
(performed by PLAXIS 3D when switching to the
tab Mesh) took significant time. But after that, the
meshing itself was performed successfully and in a
shorter time frame.
Different stages had to be calculated using
different solvers. The Classic solver used less
memory, but it took more time to calculate.
The Pardiso solver worked faster, but could give a
singular matrix in case of some structural elements.
It’s still not clear why. But fortunately, the Picos
solver was able to deal with the situation in which
structural elements where switched on and soil
element where switched off due to the excavation.
So, by switching between the different solvers,
the whole calculation could be finished efficiently.
The calculation of the stages required more than
14 GB RAM-memory and around 30 GB of disk
space. To prevent a lack of space available for the
Windows temporary folder (TEMP), the project
was saved after each phase was calculated.
This was done using the commands runner.
Monitoring
The impact of the excavation on the surroundings
is closely monitored, using inclinometers in the
diaphragm walls and a large number of measuring
bolts in the facades of the adjacent buildings.
The estimated horizontal deflection of the
diaphragm walls using the PLAXIS 3D model was
about 20 to 30 mm. The measured horizontal
deformations were smaller: just a few millimetres
with a maximum of 7 mm.
The lower deformations occurred in reality can be
attributed to:
• the higher stiffness of the Potklei. The
overconsolidation ratio of the clay was not
taken into account in the model, which in other
words means an underestimation of the initial
horizontal stresses and thus in the actual elastic
moduli of the HS model
• the higher stiffness of the diaphragm wall. In
reality, the diaphragm wall showed practically
uncracked behaviour, but in the model an
elastic modulus corresponding to a cracked wall
was considered
Moreover, the final measured subsidence of
the adjacent structures are lower than the
estimated in the model. They are compared in
the following paragraph for: a) the buildings at
the North and East side of the excavation at a
perpendicular distance of 5 m from the excavation
and b) buildings at the corners of the excavation,
including the monument.
As a result of the installation of the various
diaphragm wall panels, the measured vertical
deformations at the North and East side of the
excavation were 1 to 2 mm. The actual excavation
and dewatering caused additional vertical
deformations of a few millimetres up to 7 mm.
The estimated deformations at the North and
East side of the excavation were 10 to 15 mm.
The monument experienced a settlement of
5 mm, whereas in the model a settlement of
6 mm was estimated.
Figure 5: Detailed modelling PLAXIS 3D
Figure 4: Vertical deformation of the adjacent structures "walk along"
Photo 1: Required local excavation to install a lower strut
Loam "Potklei" Sand
γ/γsat
[kN/m3
] 19/21 14,5/18,5 19/21
E50
/Eoed
/Eur
[MN/m2
] 9/4,5/36 12/6,64/48 110/110/440
c [kN/m2
] 2,5 20,0 0
ϕ [°] 27,5 17,5 32,5
Table 2: Main soilparameters

Figures 7 and 8 show graphs of the measured
and calculated settlements as well as the allowed
deformation at 4 relevant points. The location of
these points are indicated in Figure 6.
These figures show that the calculated settlements
are less than the allowed, thus the risk of damage
of the buildings was acceptably low. The actual
measured settlements are lower and some points
even showed upward rather than downward
movement.
This phenomenon could be explained by the fact
that, in the model, the upward pore pressures
acting at the bottom of the underwater concrete
slab were balanced by a non-existent external
surface load. Hence, there is an increase in
compressive stresses around the bottom of the
excavation with a correspondent increase of
downward movement. In reality, the Gewi and
Tubex piles transfer the force generated by the
upward pore pressures to deeper ground layers
without increasing the compressive stresses at the
bottom of the excavation. Since the excavation
produces a reduction in compressive stresses at
the bottom of the excavation, the soil around this
location will experience an upward movement.
Clearly, this leaves the possibility of a net upward
movement at the surface, as long as the sum of
the settlements experienced by the shallow layers
is lower than the sum of upward movements
experienced by the deep layers.
By adding vertical embedded or volume piles
in a PLAXIS model underneath the underwater
concrete, the increase of compressive stresses
produced by the external load could be avoided.
This could result in a more realistic deformation of
the surrounding. Alternatively, the external load
can be combined with a decreased γsat of the
underlying ground layers, in order to reduce the
negative effect of the external load.
Conclusions
With the use of a comprehensive PLAXIS 3D
model, including temporary structural elements
and a detailed phasing, it is possible to optimize
the implementation of a large and complex
deep excavation successfully. To calculate more
accurate vertical deformations of the surrounding
soil mass in case of a deep excavation with
underwater concrete, it is important to model the
unloading due to the excavation. This could be
done by including the tension piles in the model.
Figure 7
Figure 6: PLAXIS 3D mesh
Figure 8
Photo 2: Photography Koos Boertjens © ABT

»The Vlaketunnel is a highway tunnel under
the canal through Zuid-Beveland in the A58
road, connecting the city of Bergen op Zoom
with Vlissingen.
In Figure 1 a top view of the canal with the track of
the tunnel is shown.
The tunnel sections beneath the canal were
built with the immersed tunnel technique. The
concrete elements of the tunnel were built in a
dock situated just beside the canal. After finishing
the construction, the dock was inundated to allow
floating of the elements and transportation to
the immersion site over water. The elements were
immersed into a pre-dredged trench of about
10 m deep. The free space between tunnel and
bottom trench was filled up with sand, that was
dredged from the Western Scheldt, and formed
a foundation layer. Also on either side and on
the top of the tunnel sand was deposed; backfill
material. To protect the roof of the tunnel against
damage caused by falling or dragging ship’s
anchors, a stone-asphalt-mattress was installed on
the top of the tunnel, see Figure 2.
To improve the maritime traffic flow through the
canal, in 1993 it was decided to remove the lock at
the north side of the canal that closes the canal of
the Eastern Scheldt estuary, and as a consequence
tidal movements from the North-sea were
introduced into the canal.
The executive department of the Dutch Ministry
of Infrastructure (Rijkswaterstaat) is responsible
for the functioning of tunnels in the Netherlands.
Deformations and settlements of the tunnels are
As part of the InfraQuest research into the sustainability of Immersed tunnels in the Netherlands, a study was
carried out at Delft University of Technology to analyze the up and down movements of the Vlaketunnel.
InfraQuest is a joint research program of the Ministry of Infrastructure, Delft University of Technology and Delft
TNO. The research was done by N. Benhaddou as a final MSc. Project.
N. Benhaddou - K.J. Bakker, Delft University of Technology
anchors. Mainly due to brittle fracture by pitting
corrosion of the anchors and in a certain extent to
tide effect, floating of one of the sections of the
eastern access ramp is occurred in 2010.
The results described in this article are based
on the research conducted on the submerged
section of the Vlaketunnel. The aim of the research
was to determine the physical cause behind the
measured up and down displacements of the
submerged section.
frequently monitored. An evaluation of the data
which has been delivered for the Vlaketunnel
indicates that the tunnel clearly shows up and
down movements, two times daily, coinciding with
the tidal movements.
Besides the immersed section, the tunnel
consists also of access ramps. To prevent the
access ramps from floating or shifting upwards,
the tunnel sections were provided with tension
Evaluation of the up and down movements of the
Vlaketunnel with cyclic analysis using PLAXIS 2D
Figure 1: Top view of the location of the Vlaketunnel
Figure 2: Cross section of the immersed section of the Vlaketunnel

Measurements
In the context of a monitoring program that was
carried out by Rijkswaterstaat, as previously
mentioned, measurements had been performed
in the tunnel in order to determine the movements
of the tunnel as a result of water level changes in
the canal. The measurements were performed
Figure 4: Graphical view of the daily measurement, April 3 2002
Figure 6: 2D Model, cross section
Figure 3: Graphical view of the measurements performed during high and low tide on March 27 - April 12, 2002
Figure 5: (a, left) CPT carried out through the floor of the tunnel in 1975. (b, right) CPT carried out before the
realization of the tunnel; (please note that the graph is in kgf/cm2
, and not in MPa, such is customary nowadays).
during high and low water periods on March 27 to
April 12, 2002. The results of these measurements
are graphically represented in Figure 3. The graph
shows the ultimate position of the tunnel during a
complete tidal cycle. The horizontal axis represents
the location of the measurement points along
the longitudinal axis of the submerged section.
The vertical axis shows the vertical displacement.
Figure 4 shows the daily variation in time of
tunnel element 1 on April 3, 2002; the blue line in
the graph indicates the water level in the canal,
on this scale in [m]. The other lines indicate the
displacement of fixed points of the tunnel element
1 (which consist of 7 tunnel segments) in [mm].

Evaluation of the up and down movements of the Vlaketunnel with cyclic analysis using PLAXIS 2D
The stone-asphalt-mattress on the top of the
tunnel is modelled with plates and interfaces and
assumed to be impermeable.
In the first calculation steps the trench excavation
and the initial construction of the tunnel was
modelled. Afterwards the impact of the tidal wave
was added by means of coupled Geo hydro-
mechanical analyses with transient hydraulic
boundary conditions along the bed of the canal.
The pressure profile representing the wave
is described by an harmonic time dependent
boundary condition with Hs
= 3,8 m, as illustrated
in Figure 7. To graphically display the results of the
analysis, two stress and deformation points are
chosen in the middle of the tunnel roof and floor.
Results
The results of the 2D analysis showed that the
immersed section of the tunnel experiences an
harmonic upward and downward movements due
to the variation in the water level in the canal.
During low tide the tunnel comes up, and
goes down during high tide, according to the
measurements. The calculated displacements
are in the order of 9.5 mm between the lowest
and highest position. Figure 8 indicates the
movements predicted with PLAXIS 2D.
The graphs shows clearly that the submerged
section of the Vlaketunnel experiences vertical
motions that are related to the water level changes
in the canal. During low tide the submerged
section comes up and during high tide it settles
down. An average subsidence and uplift of
between 4 and 8 mm respectively, is registered.
From the measurements shown in Figure 4 it can
be deduced that the tunnel movement and water
level changes are not in phase. Maximum water
level and maximum subsidence occurs not at the
same time. This indicates the presence of a certain
resistance by means of (low) permeability of the
foundation and the back fill material. A phase shift
of up to 1.0 hour is observed.
Soil survey
In order to infer soil parameters for the sand
foundation layer, penetration data, that was
realized by CPT testing through the bottom of
the tunnel direct after the realization in 1975, was
re-evaluated. The CPT data, see Figure 5, shows
that the cone resistance of the foundation layer -
consist of sand which has been filled into the free
space between the bottom of the tunnel and the
trench - is about 3 MPa. Below this layer the soil
profile mainly consists of loosely packed sand of
about 5 meter, followed by the Pleistocene sand.
A typical behaviour of loose sand under cyclic
loading is contraction and dilatancy.
Hypothesis
After analyzing the measurements and the soil
survey a hypothesis regarding the physical
cause of the motions of the immersed section is
formulated. It is assumed that the soil beneath the
tunnel exhibits elastic behaviour. Directly after the
high water peak the saturated subsoil just beneath
the immersed section experiences an increase
in effective stress. This causes compaction in
the loosely packed sand layer and the water
is discharged from this layer into adjacent soil
profile. After dissipation the tunnel section tends
to settle. Directly after the low tide the opposite
effect takes place. The now slightly denser sand
layer experiences some decrease in effective
stress that results in a small expansion of the soil
skeleton. Water from the adjacent soil profiles is
attracted and the tunnel tends to move upwards.
Model
Based on the soil survey, which consisted of CPT’s
a parameter set was established. The parameters
are assumed based on overall experience with
soil materials and NEN9997-1. The parameters
used are summarized in Table 1. The topology was
been modelled as indicated in Figure 6. In order
to minimize the effects of the boundaries the
geometry has been chosen 100 meter wide and 50
meter deep.
The essence of the model is that it describes the
deformation of the soil layers beneath the tunnel
due to time-dependent variation in the water
level. So an integrated Geo hydro mechanical
model was established, that includes the time
dependent loading on one hand and on the
other hand describes the effects of this loading
on soil deformation.
The tunnel has been modelled as a soil body with
linear elastic properties (for concrete).
To simulate the interaction between tunnel lining
and soil, interface elements were applied.
The aim of the analysis was not so much calibrate
the exact same value of the displacement as well
as to explain the physical principal that is behind
the displacements. For that matter the results of
the analysis largely confirmed the hypothesis. The
supply and discharge of water mainly takes place
through the Pleistocene aquifer sand package
(Figure 9 and Figure 10).
What also leads to the movements is the infiltration
of water from the bed of the canal - through the
back fill sand next to the tunnel - to bottom tunnel.
Infiltration is caused by pressure differences
above and beneath the tunnel during high and
low tide. Approximately 15% of the total vertical
displacement is due to this mechanism.
A snapshot of the plasticity in the loosely packed
sand layer implies that the presumption that this
layer is subject to compression during high water is
correct. Due to compaction of the grains, the pore
water extruded from this layer. The maximum stress
state is then reached, as depicted in Figure 11.
The failure points that occur during high tide at the
interface between tunnel and soil, implies the up
movement of the tunnel. High shear stresses occur
on both sides of the tunnel, which means that the
soil retains the tunnel to go upwards (Figure 12).
Figure 7: Used hydraulic boundary condition in PlaxFlow
Tabel 1: Model parameters PLAXIS 2D
Figure 8: Predicted up- and downwards movements

Evaluation of the up and down movements of the Vlaketunnel with cyclic analysis using PLAXIS 2D
References
• Kombinatie Vlake (1974) ‘Het onderstromen der
tunnelelementen Vlaketunnel’.
• InfraQuest (2011) ‘vervormingen van afgezonken
tunnels in Nederland’.
• Rijkswaterstaat (2010) ‘Metingen zinkgedeelte
Vlaketunnel’.
• Plaxis bv (2012) Manual 2D ‘Material Models
Manual’.
The order of magnitude of the movements is
strongly influenced by the permeability of back fill
sand material and the stiffness of the foundation
layer. Whereas the phase shift between tide
and movements is mainly influenced by the
permeability of the loosely packed sand layer.
This has been shown by mean of a sensitivity
analysis, whereby the strength, stiffness and
permeability parameters of the soil layers were
incrementally varied.
Removing the stone-asphalt-mattress on the top
of the tunnel leads to a slight reduction of the
vertical displacement of the tunnel. This has been
shown with a calculation where the stone-asphalt-
mattress is removed.
Effect of the vertical movements on the tunnel
as a construction
The submerged section behaves under influence
of tidal movements in the canal as a long beam
with two support point at the end; the maximum
displacement occurs in the middle. The up and
down movements of the tunnel primarily affect
the rubber expansion joints between two adjacent
tunnel elements.
The movements leads to settlement differences,
which results in rotations. For immersed tunnels,
the requirement regarding allowable rotation in
the joints is determined at 0.0025 rad.
The calculated maximum rotation in the joints is
0.001 rad and complies with the requirement.
The calculated rotation is determined based on
the upper limit for closure level of the Eastern
Scheldt Barrier.
Conclusions
The opening of the canal through Zuid-Beveland
to the tidal movements in the Eastern Scheldt
Barrier has triggered a soil water interaction that
makes the tunnel move up and downward twice a
day. The maximum displacement is limited by the
level at which the Eastern Scheldt Barrier is closed.
The maximum rotations in the tunnel joints stay
below the critical limits. The influence of the tidal
movements on the tunnel joints on a long term
time frame has not been evaluated.
Acknowledgments
This study was a part of the InfraQuest research
into the sustainability of Immersed tunnels in the
Netherlands. The authors wish to thank TNO and
Rijkswaterstaat, for enabling the performance
of this study; thanks are given to Dr. A. Vervuurt
of Delft TNO, to facilitate work space and to Mr.
Wolsink, for supplying the monitor data and the
fruitful discussions on the topic.
Figure 9: Illustration water flow towards the tunnel during low tide
Figure 11: Occurred plastic points during high tide Figure 12: Occurred plastic points during low tide
Figure 10: Illustration water flow off the tunnel during high tide

Pavement service life prediction
and inverse analysis with PLAXIS 3D
»In civil engineering structures, failure occurs
when internal stresses exceed their ultimate
limit strength. In particular cases, when structures
are subjected to repeated loading, failure occurs
due to fatigue even if the stresses are much lower
than the material strength. Fatigue phenomena
can be observed in pavements or structures
subjected to dynamic loading, e.g. fatigue of
bridge elements. Fatigue is a very complex
phenomenon in which material accumulates
incremental structural damage due to repeated
loading until it reaches failure. The physical
damage is induced by micro-cracks that develop
in the material, e.g. asphalt. At a macroscopic
scale, this means a significant reduction in
stiffness. In order to design structures against
fatigue, we therefore need to be able to predict
the damage development and the consequent
stiffness reduction during the service life.
Another important issue in the design of
pavements or other geotechnical structures is the
reliability of soil material parameters, in particular
the stiffness. This paper shows how these
parameters can be obtained from inverse analysis
of pavement deflections and potentially from
geotechnical measurements.
Service life prediction for pavements
The stress levels in a flexible pavement structure
are generally much lower than the failure values.
Instead, pavement "failure" is due to accumulation
of damage and is generally related to structure
Predicting the end of service life of an engineering structure, or obtaining parameters from inverse analysis of measured forces
or displacements, is a complex task which requires deep knowledge of material behaviour and software development. In this
paper it is shown how these two procedures can be carried out by writing a subroutine with the software MATLAB to run with
predefined input data, pre- and post-processing a finite element model in PLAXIS 3D. The examples show how it is possible
to predict the rest of service life of an airport pavement and to obtain layer stiffness parameters from inverse analysis of a
three-dimensional deflection bowl. The developed MATLAB routines allow the field of possible PLAXIS 3D applications to be
extended considerably.
Carlo Rabaiotti, PhD, Basler & Hofmann AG, 8133, Esslingen (Zurich), Switzerland, contact information: carlo.rabaiotti@baslerhofmann.ch
serviceability, in particular the amount of cracks
and rutting in the asphalt layer. In the following
sections, the methods followed for assessing
the development of damage in asphalt and the
consequent stiffness reduction are described.
Assessment of damage
In the adopted method, damage in asphalt is
defined based on the number of cycles to failure
NF
that are obtained as a result of fatigue tests.
The (incremental) damage ∆D is obtained by
dividing the number of cycles at each calculation
step n (e.g. number of load applications in one
month) by the number of cycles to failure.
D
N
n
F
D = (1)
Since the number of load cycles to failure NF
is
not constant, and it varies with temperature,
material stiffness and strain amplitude, the fatigue
Figure 1: Incremental calculation and accumulation of damage according to Miner's rule.
The incremental damage at the calculation step i – 1 is equal to D N
n
i
F
1
i 1
D ==
=
.
In the calculation step i the incremental damage becomes D N
n
i
fi
D = where, N NF Fi i1 ==
and the total damage is equal to D Di
l
i1R D= = (t = temperature, i = increment, e = critical strain)

characteristics have in principle to be determined
based on a large number of tests under different
conditions. In this study, the number of cycles
to failure for the asphalt is instead predicted
according to the semi-empirical fatigue law that is
described in the AASHTO 2008 pavement design
guide for alligator cracking. This predictive
equation depends on the highest (critical) tensile
strain level at the bottom of the asphalt base
layer εcrit
, the elastic modulus E and empirical
coefficients. The total damage D is obtained by
adding the increments (Eq. 2) after each iteration
according to Miner's rule.
D Dii
l
1
D=
=
/ (2)
Of course, this is a very simple model for the
calculation of cumulative fatigue damage (see
also Fatemi and Yang, 1998). This approach has
been chosen because of its simplicity, and it is still
widely accepted for practical applications.
Despite its simple formulation, the calculated
damage accumulation is non-linear: the
incremental damage Di3 is not constant
(Figure 1), since NFi depends on the current
stiffness and critical strains and climatic
(temperature) conditions.
Assessment of stiffness reduction due to damage
As already discussed, material damage is
responsible for the reduction of stiffness in
asphalt. In literature there are several approaches
to relate damage to stiffness in asphalt (see also
Collop and Cebon, 1995). According to a well-
known criterion, fatigue failure (100% damage)
in asphalt is defined as the number of cycles
to failure NF after which the material stiffness
(elastic modulus) reaches half of its initial value.
Therefore, in the procedure adopted in this paper,
the stiffness decay is obtained by multiplying the
asphalt elastic modulus by a factor:
D
1 2
iRD
- (3)
The asphalt stiffness is additionally modified
at each step based on average monthly layer
temperature, according to the well-known Van
der Pool monographs. During each iteration, the
calculated reduced stiffness is adopted as an input
for a new finite element (FE) calculation, and the
new critical tensile strains in the asphalt layers are
obtained. Once the new critical strains and current
stiffness have been obtained, a new value of load
applications to failure NFi
is predicted and the
incremental damage (Eq. 4) and the new stiffness
can be assessed again.
D N
n
i
Fi
D = (4)
The iteration procedure stops when the level of
damage reaches 100%. The overall procedure is
summarized in Figure 2.
Algorithm implementation
Predicting service life generally requires carrying
out hundreds of calculations, one for each
calculation step (e.g. 1 month). Therefore an
automated procedure needs to be implemented.
A major advantage of PLAXIS 3D is that the model
can be pre- and post-processed and run under
DOS. For pre-processing, a special .log file should
be created by the MATLAB-based software with
the instructions for the PLAXIS 3D command line.
The coded output is then translated into a .txt file
with the cbin.exe program. Special software has
therefore been written in MATLAB that writes the
PLAXIS 3D commands in the .log file and starts the
calculation. The critical strains at the bottom of
the asphalt base layers are calculated in a three-
dimensional finite element model implemented in
PLAXIS 3D.
After the calculation finishes, MATLAB runs
the translating output software cbin.exe and
reads the stresses in the gauss points. MATLAB
calculates the strains from the stresses according
to the elastic constitutive model adopted for
modelling the asphalt behaviour.
The asphalt stiffness for the next calculation is
obtained, as already mentioned, by considering
the damage level and the average monthly
temperature during service hours of the airport.
The procedure is illustrated in Figure 3.
Figure 2: Simulation of the damage process due to fatigue in asphalt Figure 3: Implemented procedure for estimating
service life (fatigue) with MATLAB (main routine)
and PLAXIS 3D (subroutine)

Assessment of service life for a rehabilitated
pavement
The software has been successfully adopted for
estimating the residual service life of the proposed
rehabilitated pavement of runway 14/32 of the
Zurich international airport. In this analysis, the
ultimate goal was not to identify the period of
time until 100% damage would be reached but
to predict the level of damage after a period of
30 years. The requirements for the service life
duration were defined by the airport authorities.
In the following paragraphs a summary of the most
relevant information on the modelling is given.
More details can be found in Rabaiotti et al. (2013).
The pavement and the loading caused by the
HSs model. In the implemented code, the results
from each calculation step are stored for the next
calculation; this means that during the simulation
the same model is always loaded and unloaded
with updated material properties.
Thanks to this feature and the choice of the HSs
model for the subgrade, it is therefore possible
to follow accumulation of plastic strains (post-
compaction) in the unbound (subgrade) layers.
In accordance with the airport’s requirements,
the performance of the rehabilitated pavement
was studied on loading and unloading the finite
element model (through the MATLAB routine) for
an equivalent period of 30 years. After this time
period, the damage was evaluated.
the sum of squared error (SSE) between calculated
and measured displacements (Figure 6).
The procedure is implemented as follows:
the MATLAB routine runs the cbin.exe program
and translates the PLAXIS output to a readable
.txt file. The calculated displacements are read
and compared to those measured. The program
calculates the objective function (SSE = sum
of squared error) and chooses a new set of
parameters for its minimization according to the
chosen algorithm strategy. It then runs the next
PLAXIS calculation with those parameters.
This procedure is carried out for several iterations
until the minimization value of the objective
function is reached.
Figure 4a: Symmetrical 3D finite element model of 1/4 of the pavement and load
(B777-300ER landing gear). The plot shows the calculated deviatoric stresses q
Figure 4b: MATLAB post-processing of pavement displacements calculated with PLAXIS 3D
landing gear were reproduced in PLAXIS 3D.
Owing to the symmetry of the landing gear
(Boeing B777-300ER), it is possible to model only
one-quarter of the pavement, and the symmetry
boundary conditions are applied accordingly.
The model dimensions of 12 x 8 x 6 m (depth) were
chosen in order to reduce the influence of the
boundary conditions on the calculated results.
A plot of the PLAXIS 3D model and an example
of the MATLAB post-processing of the results
are shown in Figures 4a and 4b. The pavement
consists of a layer of asphalt (wearing course and
base), cement treated material (sub-base) and
subgrade. An interface layer between base and
sub-base layer was also modelled.
The asphalt and the cement treated base were
modelled with a linear elastic constitutive model.
The changes in the asphalt elastic modulus due to
temperature and damage were calculated by the
MATLAB routine within the previously described
procedure. The temperatures were obtained
from measurements carried out in the layers of
an instrumented track nearby, during the years
2003–2005 (Rabaiotti and Caprez, 2007).
To model the mechanical behaviour of the
subgrade, the constitutive model chosen is the
hardening-soil with small strain stiffness (HSs)
model. Since the stiffness of the asphalt layers
decreases because of damage during the service
life, the compression stresses on the subgrade
become higher. The increase in the stress
level produces irreversible plastic strains in the
subgrade; these can be simulated with the adopted
Figures 5a and 5b show the development of the
temperature-dependent asphalt stiffness and
accumulation of damage during the service life.
It was found that the proposed rehabilitation
design fulfilled the requirements to last for 30 years.
Inverse analysis: back-calculation of road
material properties based on three-dimensional
deflection bowl
The procedure for back-calculating the
stiffness of a pavement material layer based
on a three-dimensional deflection bowl is
extensively described in Rabaiotti (2008). The
three-dimensional displacement of a pavement
under a track load is measured with the ETH
Delta test device. The depth and shape of the
deflection bowl depend on the layer thickness and
stiffness. If the thickness of the layers is known, it
is possible to back-calculate the stiffness of the
single layers within inverse analysis. The inverse
analysis is carried out by seeking the stiffness
parameter values that allow a good match to be
obtained between the measured and calculated
displacements of the pavement. The parameters
can be obtained with different strategies (gradient
or non-gradient based optimization methods)
that are already implemented in the MATLAB
Optimization Toolbox.
The inverse analysis procedure is carried out in a
very similar manner to the simulation of the service
life: the parameters (generally Young’s moduli of
the individual layers) are chosen by the algorithm
in order to minimize the objective function fobj,
e.g.
In the example presented in this paper, inverse
analysis was carried out using ETH Delta
measurements (see also Rabaiotti et al. 2013) on
runway 16/34 of Zürich international airport.
The runway was rehabilitated by replacing the
old concrete slabs with an equivalent asphalt
layer in 2008.
By observing the change of layer stiffness in
different runway sections, in particular the heavily
loaded initial part (threshold) and lightly loaded
middle section, it was possible to quantify the
development of the damage in the asphalt.
The results are extensively discussed in Rabaiotti
et al. 2013. Figure 7 shows the match between
back-calculated (lines) and measured (dots)
transversal shape of the deflection bowl for
different longitudinal wheel positions.
Other possible applications
The MATLAB software allows for a wide range
of future possible applications to be developed.
Inverse analysis can, of course, be extended
to many geotechnical engineering problems,
e.g. back-calculation of soil parameters from
deformation of retaining walls of excavations.
An interesting field could be the implementation
of more advanced statistically based analysis of
geotechnical or civil engineering structures, in which
the input parameters or even the model geometry
can be set according to statistically distributed
values. The resulting distribution of the output,
e.g. internal forces in the structure, could allow the
safety of the structure to be statistically determined.

Conclusions
Simulating the service life of structures subjected
to repeated loading (fatigue) or using inverse
analysis procedures to determine stiffness
parameters, requires the implementation of
predictive and optimization algorithms. In the
present study, a service life prediction algorithm
and an optimization procedure have been
implemented in MATLAB.
PLAXIS 3D was adopted as a subroutine to
calculate the critical strains in the asphalt layer and
to simulate the accumulation of damage. The same
model, representing the rehabilitated pavement
of runway 14/32 at Zürich international airport,
was loaded and unloaded with changing asphalt
stiffness for an equivalent period of 30 years.
It was shown that the proposed rehabilitation
was able to fulfill the 30 years' service life
requirements. Additionally, a modified version
of the MATLAB routine was adopted for inverse
analysis of ETH Delta measurements carried out
on runway 16/34, which was rehabilitated with the
same strategy in 2008.
The results of the inverse analysis allowed the
development of the damage in the asphalt and
cement-treated base layer to be quantified.
Linking PLAXIS 3D and MATLAB for pre- and
post-processing considerably broadens the
field of possible applications for finite element
calculations.
References
• American Association of State Highway and
Transportation Officials (AASHTO) (2008).
Mechanistic-Empirical Pavement Design Guide,
A Manual of Practice, Interim Edition.
• Collop A. and Cebon D. (1995). “Modelling
Whole-Life Pavement Performance”. Road
Transport Technology 4, University of Michigan
Transportation Research Institute, pp. 201–212.
• Fatemi, A. and Yang, L. (1998). "Cumulative
fatigue damage and life prediction theories: a
survey of the state of the art for homogeneous
materials". Int. J. Fatigue, Vol. 20, No. 1, pp. 9–34.
• PLAXIS 3D reference manual (2013).
• MATLAB and Optimization Toolbox Release
(2013b). The MathWorks, Inc., Natick, Massachu-
setts, United States.
• Rabaiotti, C. (2008) "Inverse Analysis in Road
Geotechnics", PhD Thesis, ETH Zürich.
• Rabaiotti, C. and Caprez, M. (2007). Unter-
halt 2000, Forschungspaket 4: Dauerhafte
Beläge, Schlussbericht zum Forschungsauftrag
2000/422, Bundesamt für Strassenbau, Nr. 1182.
• Rabaiotti, C., Amstad, M., and Schnyder, M.
(2013) Pavement Rehabilitation of Runway 14/32
at Zürich International Airport: Service Life Pre-
diction Based on Updated Incremental Damage
Approach. Airfield and Highway Pavement 2013,
pp. 609–627.
Figure 5a: Decrease of temperature-dependent asphalt stiffness (shear modulus
G) during runway 14/32 service life
Figure 5b: Accumulation of damage during runway 14/32 service life
Figure 6: Inverse analysis procedure, coupling MATLAB
(main routine) and PLAXIS 3D (subroutine)
Figure 7: Measured (dots) and back-calculated (lines) deflection bowl induced by a track
load (twin tyre). The test was carried out on runway 16/34 of Zürich international airport

Recent activities
PLAXIS 2D 2015 has been released in the
first quarter of the year, adding again several
new features a new module and scores of
improvements to the program.
One of several big additions is the new User
Defined Soil Model for Shotcrete, which you
already read about in the new developments
section. Plate elements have been extended with
non-linear behaviour, allowing users to specify
M-kappa diagrams.
The embedded beam row now offers visualization
for the connection type and more advanced
options for defining lateral skin resistance and
axial skin resistance, which users have marked
as important to have. A new and more powerful
implementation of Sensitivity analysis and
Parameter variation has been added as well.
In the Output program, a command line is
introduced which allows users to retrieve
displacements or stresses from objects or
coordinates via typed commands. Output has
also been extended with the Remote Scripting
API, which creates new possibilities for user
defined interaction between the Input and Output
programs. With the addition of the new 2D
Thermal module user can now model the effects
of temperature in geotechnical projects.
PLAXIS VIP subscribers can contact the Sales
department to activate their free license upgrades
or request the new Shotcrete Model.
Since the last bulletin edition Plaxis has been quite
active again to share knowledge with new users
and meet with customers. In November Plaxis
met new and familiar faces at the annual Hydraulic
Engineering Day in the Netherlands, where a lot of
companies, governmental bodies, as well as Applied
Universities with an interest in anything related to
hydraulic engineering came to visit. In the same
month, two back-to-back workshops organised at
the PLAXIS headquarters in Delft, had participants
focused on the subjects of Dynamics and PLAXIS 3D.
Plaxis also hosted a workshop on unsaturated soil
behaviour at the annual national conference on
Geotechnical Engineering and Soil Mechanics in
Mexico.
The new year started off with the ever popular
Standard Course on Computational geotechnics at
Schiphol, the Netherlands, drawing people worldwide
to learn the very basics of PLAXIS both in terms of the
program as well as the scientific background.
February was in particular an eventful month in
Europe. The fifth edition of the Belgian PLAXIS
users meeting was another success. Together with
Besix interesting sessions were organized about
topics like dynamics and excavations in urbanized
settings.
In Italy a workshop on tunnelling was held at Arup,
Milan. This full day workshop focused on the use
of PLAXIS 2D for design and analysis of tunnels,
addressing topics like tunnel lining, rockbolts.
In Germany, Finite Elemente in der Geotechnik
& 3D Analysen - Theorie und Praxis, one of our
courses fully lectured in german, was very well
attended. Its format is similar to other courses held
worldwide, focusing on the more advanced soil
models and introducing PLAXIS 3D as well.
Middle East
After organising several beginner courses in the
United Arab Emirates over the past years, Plaxis
has held the first Advanced Course in Dubai in
October. The course, covering rock modelling,
soil improvement and how to get material model
parameters from field reports, was attended by
delegates from the U.A.E. and the neighbouring
countries.
In December the second edition of the Turkish
PLAXIS users meeting was held in collaboration
with Geogrup, our local agent. This event where
users presented their own works with PLAXIS and
learned a bit about the future development in
PLAXIS, was well attended, paving the way for a
third one next year.
Plaxis Americas
In October of 2014 an advanced course was
organized in Houston. This busy advanced course
brought together a diverse group of engineers from
across the US and Canada, most with many years
of PLAXIS experience under their belt (some up to
twenty years!). The course included an optional day
dedicated to offshore geotechnics, topics on that
day included cyclic loading effects, NGI-ADP model,
seafloor anchors, mud mats, and suction anchors.
PLAXIS seminar, South Korea

Another focused event was the Tunneling Master
Class which was held in February at Columbia
University in New York. This full workshop focused
on the use of PLAXIS 2D for design and analysis
of tunnels, including the 2D Tunnel Designer
released in PLAXIS 2D AE. Emphasize was placed
on topics relevant to tunneling including soil-
structure interaction, groundwater, tunnel lining
and rock bolts, and how these can be modeled
efficiently using finite element.
The brand new and sophisticated Shotcrete
User Defined Material Model was explained, and
the equally new 2D-Thermal module was briefly
touched upon – both are new developments that
further enhance PLAXIS’ capabilities for tunnel
engineering.
Additionally, in the past months many pleasant
conversations and productive discussions
took place at the Plaxis booth at Dam Safety in
San Diego, Canadian Geotechnical Society’s
conference in Regina, Deep Foundation Industry
conference in Atlanta, and the International
Foundations Congress and Equipment Expo
(IFCEE) 2015 in San Antonio.
We are committed to the North American
geotechnical community and will continue to visit
and exhibit at events across North America in
2015 and beyond. Make sure to receive our emails,
check the list of upcoming events and follow us on
social media to see when and where you can meet
us in person. We look forward to meet you!
Plaxis AsiaPac
Two technical seminars on the use of PLAXIS
2D and 3D were conducted on the 26 and 27
of February in Seoul. These two activities were
organized by BasisSoft Inc. and PLAXIS AsiaPac.
These two application based seminars were
attended by local engineers and existing users.
We look forward to return to Seoul in the 3rd
quarter of 2015 to conduct two advanced
application modules.
Expedition Masai
Plaxis sponsored team “CecileMandy4Masai”
for their participation in Expedition Masai 2014,
a week long hike in remote highlands and Masai
country in Tanzania in support of AMREF Flying
Doctors.
Dr. Mandy Korff (Deltares, chair of Dutch
Geotechnical Society), one of the team members,
sent us her report.
"Hiking for charity is an ideal combination of
adventure and giving back. That is the idea of
Expedition Masai, a 5 day charity walk through the
Crater Highlands of Tanzania.
We depart from our camp on the rim of Empakaai
Crater and head north, in the direction of Lake
Natron. We walk through remote (high) lands,
inhabited by Masai and their cattle. The Masai
are proud people and can be seen from far as
they dress in bright red colours, which even lions
recognize, keeping their distance. The expedition
members raised money for AMREF Flying Doctors,
and we visit some of their projects during the week.
AMREF’s philosophy is to work in small projects,
which are owned by the local population.
These projects make an immense difference in the
life of the people here; general health improves
and more girls can go to school because they do
not have to carry water all day. We keep these
stories in mind while walking through the scenic
landscape of the Crater Highlands, grasslands
with Acacia trees dotted in. When we descend
out of the Highlands towards Lake Natron, the
temperature rises above 35 degrees. We pass an
air strip where the next day the Flying Doctors
actually land, although not more than two lines of
rocks in the middle of a sand mass. After 5 days of
hiking we reach Lake Natron, with just one small
blister, proud and full of admiration for the way the
Masai live in this harsh environment. Thanks to the
people we met, this week has become so much
more than a holiday or sporty adventure.
Thanks to our sponsors, especially Plaxis, this has
become a walk of appreciation and gratitude,
both from the expedition members as well as the
people benefitting from AMREF support".

Title
16 Jalan Kilang Timor
#05-08 Redhill Forum
159308 Singapore
P.O. Box 572
2600 AN Delft
The Netherlands
Plaxis Americas Office
USA
Tel +1 650 804 4729
www.plaxis.com
Tel +31 (0)15 2517 720
Fax +31 (0)15 2573 107
Plaxis AsiaPac Pte Ltd
Singapore
Tel +65 6325 4191
Plaxis bv
Computerlaan 14
2628 XK Delft
9 April
Singapore Plaxis Users Meeting
Singapore
13 April
Seminario sobre El Uso Practico de Modelos
Constitutivos
Santiago de Querétaro, Mexico
14 - 17 April
Curso Avanzado de Geotecnia Computacional
Santiago de Querétaro, Mexico
15 April
PLAXIS 2D Workshop for Excavation in Soft Soils
Oslo, Norway
10 - 13 May
ISRM Congress 2015
Montreal, Canada
19 - 22 May
Standard Course on Computational
Geotechnics & Dynamics
Berkeley, USA
28 - 29 May
European Plaxis Users Meeting 2015
Gescher, Germany
2 June
Workshop on Advanced Modelling in PLAXIS
Delft, The Netherlands
2 June
Workshop Utilisation de PLAXIS 2D pour
la Modélisation des Fondations en Géotechnique
Paris, France
3 June
Workshop Dynamics in PLAXIS
Delft, The Netherlands
7 - 10 June
Rapid Excavation and Tunneling Conference 2015
New Orleans, USA
8 June
Introducción al PLAXIS 2D
Buenos Aires, Argentina
9 - 12 June
Curso Avanzado de Geotecnia Computacional
10 - 12 June
International Symposium on Frontiers
in Offshore Geotechnics
Oslo, Norway
22 - 24 June
Curso de Geotecnia Computacional
Madrid, Spain
22 - 25 June
Standard Course on Computational Geotechnics
Manchester, United Kingdom
28 June - 1 July
49th ARMA Rock Mechanics Symposium
San Francisco Ca, USA
13 - 17 September
ADSO Dam Safety
New Orleans, USA
13 - 17 September
XVI ECSMGE Conference
Edinburgh, United Kingdom
15 - 19 September
PLAXIS Advanced Course
Melbourne, Australia
20 - 23 September
GEOQuébec 2015
Québec, Canada
21 - 24 September
PLAXIS Standard Course
Brisbane, Australia
7 - 10 October
Eurock 2015 & 64th Geomechanics Colloquium
Salzburg, Austria
12 - 15 October
DFI 40th Annual Conference
on Deep Foundations
Oakland Ca, USA
13 - 16 October
ISGSR Symposium
Rotterdam, The Netherlands
3 November
Geotechniekdag 2015
Breda, The Netherlands
9 - 13 November
15th ARC
Fukuoka, Japan
15 - 18 November
XV Pan-American Conference
1 - 2 December
STUVA 2015
Dortmund, Germany
Upcoming Events 2015
2500 Wilcrest Drive
Suite 300
Houston TX 77042
VACANCIES
GEOTECHNICHAL ADVISORS
(SCIENTIFIC) SOFTWARE DEVELOPERS
www.plaxis.com/jobsFore more information about our vacancies please take a look at our website

Plaxis bulletin 37 2015

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Plaxis bulletin 37 2015