Division of Information Technology, Engineering and the Environment
Structural Materials and Assemblies Group
Structural Materials and Assemblies Group
The City of Salisbury has supported applied research into
the effects of street
trees on pavements since the year 2000. Currently the City, along with the Local
Government Association, is sponsoring postgraduate research into the
suitability of street trees on expansive clay sites. Aaron O'Malley's
PhD research is summarised below:
The combination of Adelaide’s (the capital city of South Australia)
reactive soils and the prevailing semi-arid climate means that houses
and pavements must withstand significant underlying soil movements.
Trees in an urban environment can add to these movements and the
patterns of deformation. As trees are an environmentally desirable part
of urban streetscapes, a field trial was initiated to study the ground
movement patterns in streets on extremely reactive ground, with an expected
movement in excess of 100 mm, in a new suburb of Adelaide. The major
objective of the study is to establish movement patterns prior to street
trees becoming established, in order to provide a benchmark for future
movements that may arise as the trees mature and gardens become
established. Ultimately the research will impact on the design of
footings.
Six sites have been established within the development for monitoring
soil moisture changes to six metres depth near street trees, away from
the trees and below the street. The raft slab footings of nearby masonry
veneer houses have been surveyed and will be re-visited in the future.
Regular level surveys of the ground surface at each site are being
undertaken. Information on deeper movements are obtained from a ground
movement station. The suitability of different street tree species is
also being studied to aid future planning and development.
