Page 20 - LWFC Catalog

With the necessary sample modifications, ASTM D2434 has proven to be an
effective method for testing permeability of PLDCC. During a large project,
buoyancy questions arose prompting the development of methods for
testing natural saturated densities in-situ, resulting from water rising through
PLDCC. Measurements of natural saturated densities were conducted
under levels of hydraulic head from 1’ – 10’. It was determined that a head
of 1’ – 2’ is enough to establish representative saturated unit weights. Natural
saturated density testing has been incorporated Castle Rock Consulting’s
D2434 permeability testing.
Wednesday 4PM - Rehabilitation of Mechanically Stabilized Earth Bridge Approach

October 4:50 PM Embankments Using Geofoam Blocks: Hybrid Approach Embankment
Concept The Northern Marmara Highway, total of 400 km long including all
20 the connections and belt routes, has recently been constructed in Turkey.
The highway route goes through the industrious zones along the Northern
Marmara Region and connects Tekirdag and Sakarya through Istanbul. The
highway was built to reduce the traffic load on the existing transportation
networks and to provide east – west transit transportation corridor which
significantly helped to relief the traffic in Istanbul. The eastern portion of
the route called Region 6 which goes through soft soil sites where various
geotechnologies were used to construct highway embankments. One of
the overpasses in the Region 6 was constructed as two span bridge with
44 m deep drilled shafts pile supported foundations. In addition, 22 m long
1.0 m diameter deep mix columns were constructed with 2 m x 2 m grid
to support the mechanically stabilized earth approach embankments to
prevent both the bearing capacity and settlement failures. However, the
improvement zone under the footprint of 7.4 and 8.4 m high approach
embankments was only kept within a limited zone of 30 m behind each
abutment. No soil improvement techniques were implemented in the
remaining footprint of the approach embankments. Mechanically
stabilized earth approach embankments were constructed using biaxial
geogrid reinforcement with steel wire mesh facing which accommodates
vegetative soil near the facing. The longitudinal slopes of the two lane
mechanically stabilized earth approach embankments were constructed
with 7.1% and 8.4% which was quite steep and created driving safety
concerns. Therefore, the rehabilitation project was prepared to create
approach embankments with 5.0% longitudinal slopes which required to
construct additional fill atop the existing embankments. If the conventional
earth was selected to construct flatter longitudinal slope, this additional
stress increase will result both bearing capacity, total and differential
settlement issues in the sections of the approach embankment where soil
improvement was not implemented initially. A comprehensive subsurface
investigation program including SPT, CPTU, PMT in-situ and laboratory
testing program were carried out by the geotechnical consultant. Based
on the subsurface profile, a portion of the existing mechanically stabilised
earth approach embankments, where there is no soil improvement, were
excavated in a stair-step fashion to satisfy the allowable bearing capacity
and settlement criteria. Then, the remaining sections were constructed using
geofoam blocks without imposing additional stress increase. Geofoam
block technology successfully implemented in thisrehabilitation project
and set a hybrid embankment model where two geotechnologies can be
utilised in transportation infrastructure.