Practice and Research of Geosynthetic Reinforced Soil Walls in Australia - Reinforced Soil Engineering: Advances in Research and Practice - page 258

system This reinforcement system overcame the construction difficulties by
running the straps between the two walls in a zigzag fashion as shown in Fig. 7 .
However, the conventional calculation model may be neither applicable nor
conservative because of the TBB configuration. The heavy setback surcharge
from the railway loading further complicated the design. Hence, a series of
nonlinear finite-element analyses was conducted to study the behavior of a TBB
wall and to develop simple design rules (Lo et al., 1996). The results of the
analyses unambiguously showed that the higher reinforcement tension would
occur for the metallic reinforcement system, but would not be applicable to the
proposed geosynthetic reinforcement system. This is because of its extensibility.
It is pertinent to note that both the reinforcement tension and horizontal
displacement profile were not sensitive to the choice of soil models and soil
parameters. As such, simple conservative design rules were established. The
cost-effectiveness of the TBB Freyssisol wall was also demonstrated in a
subsequent project, the Y-Link Railway project, which involved the
construction of GRS walls up to 8.5 m in height supporting the elevated
section of a railway track.

4.3 Measurement of Soil Temperature

The temperature in the select fill affects the stress rupture curves and hence the
value of T dr . It may also have an effect on the hydrolysis of polyester
reinforcement if the soil temperature is significantly higher than 20 8 .The
temperature in the reinforced zone of a GRS wall located in Western Sydney was
monitored by the SRA of New South Wales for several months during 1994. The
monitoring period included all the summer months and extended into early
winter. Thermocouples were installed at various distances from the wall facing,
starting at a distance of about 300mm. In addition to having thermocouples
installed in the GRS wall, a benchmark thermocouple was also installed to
measure the shaded air temperature at the GRS wall location. Continuous
temperature logging was undertaken. The test data indicated that maximum soil
temperature at about 300mm from the facing was 35 at 1m

from the facing. The temperature at about 300mm from the facing was also close
to the air temperature. The maximum soil temperature relative to the latitude and
the coastal location of Sydney may appear to be high relative to the data
presented by Yeo and Pang (1996). However, the black asphalt pavement of this
wall may increase the soil temperature. It is also important to note that the data
reported by Yeo and Pang (1996) were based on two readings per day, whereas
the RTA data gave a daily maximum because of continuous data logging. This
fact needs to be considered in assessing the influence of measured soil
temperature on the long-term capacity of geosynthetics.

8 , decreasing to 26 8