January/February 2022 - 88

For example, bridge damage was
visualized in Trooz, Belgium, due to
flooding of the river Vesdre. The twospan,
reinforced concrete bridge experienced
loss of global stability driven by
vertical settlements and rotation of the
middle pier, as suggested by LiDAR
photographs. Due to the accurate, 3D
point cloud capabilities of the LiDAR
scan, the model will enable post-visit
measurements (e.g., rotation, tilt, deck
settlement and bridge geometry) that
were not measurable in the field.
Bridge damage in Walporzheim
Reimerzhoven. Both cable span bridges
had an abutment still standing, while
the bridge deck had been lifted up at its
opposite support, and subsequently
rotated (and failed) in the downstream
direction. The bridge deck of a twospan,
reinforced concrete bridge in
Dernau collapsed instead due to
dest ruct ion of the middle pier
foundation during flooding.
Less severe bridge damage was also
observed in many other flood areas (e.g.,
E r f s t ad t , Eusk i r chen and Bad
Münstereifel); observations of damage
in these areas suggested particularly
weak points at the interface between
water, the soil and foundation elements.
The team documented dozens of cases
of substantial scour to the backfill of
abutments (while the abutment
structure itself remained intact), as well
as multiple instances of soil erosion
underneath riprap, and bridge scour
protection at the foundation level.
During the team's visit, many areas
still lacked clean water, electricity and
other utilities. Telecommunication
coverage was largely re-established
within 5 to 7 days; however, most
residents had no opportunity to charge
cell phones or other electronic devices.
Oc tobe r news r epo r t s sugges t
electricity has been re-established in
90% of the region, yet several areas still
lacked access to drinking water then.
Aside from aerial and terrestrial
photography obtained, bridge damage
and that to other key infrastructure
components was further documented
88 * DEEP FOUNDATIONS * JAN/FEB 2022
Otlerbruecker, Bad Neuenahr Ahrweiler before flood
(credit, www.aw-wiki.de/w/index.php?curid=49168)
Otlerbruecker, Bad Neuenahr Ahrweiler during GEER
team visit
Drone imagery was also collected to
Road bridge in Dernau, Germany
through light detection and ranging
(LiDAR) surveys, UAV imagery, multispectral
photography, in situ sampling,
and complimentary on-site data collection
and observation. LiDAR is a remotesensing
technique that uses laser light to
densely sample the three-dimensional
(3D) location and orientation of objects;
those measurements were of particular
interest in the reconnaissance, as this
technology provides high-resolution 3D
documentation of damage. In particular,
LiDAR produces a point cloud that can be
managed, visualized, analyzed and
shared using GIS and other 3D
visualization software.
generate 3D structure from motion
(SfM) models. The models present a
highly mobile, cheaper alternative to
LiDAR, but lack the capabilities of subcentimeter
scale spatial resolution; the
SfM models created from this mission
had roughly 0.79 in (2 cm) resolution
with measurement errors of approximately
3.1 in (8 cm) in plan view, and 5.1
in (13 cm) in vertical. For instance, a 3D
SfM model was acquired when the team
visited the Steinbach Talsperre located
between Euskirchen and Bad Muenstereifel;
this is a dam that overflowed
during the event but remained
structurally intact. Deep head cuts,
sometimes deeper than 79 in (2 m), were
observed on the downstream side of the
dam immediately following the flood
event. The SfM model was fully able to
capture the head cuts as well as the
general geometry of the dam and
allowed for in-depth processing. At the
time of the visit, the dam reservoir had
been emptied and repair work was
underway.
http://www.aw-wiki.de/w/index.php?curid=49168
January/February 2022

Table of Contents for the Digital Edition of January/February 2022
