Hi Justin, great presentation, are there any relevant codes or engineering texts that clearly delineate the responsibilities of the permanent and temporary works designers?
Do you have any thoughts on AS 4687 Temp Fencing code, in particular table 4.5 which states ""Design wind speed""? I have had many arguments with suppliers who believe 15m/s is an appropriate design wind speed for a region A temp fence acting as a hoarding.
Can you suggest some literature or design guides to design scaffold structures to AS codes? Scaffolding is something that is done badly and not well understood in my industry i.e. resource.
Can you define the scope difference between temporary and permanent work designer responsibilities (i.e. effects of TW on PW OR temp stability of structures while being constructed)?
Can Justin elaborate on the modelling of reinforcement cage such as connection between bars? Is any collapse of reinforcement cage due to its flexiblity?
After installing the edge protection and handrails on top of the building based on approval required by the airport authority, did you get an approval sign off personally after they paid you a visit to ensure compliance?
Speaker Justin Smith will dispel the myth that temporary works is temporary and, therefore, does not require the same level of attention and detail that occurs with permanent structure design
Drilling Fluids for the Temporary Support of Deep Excavations
By Dr Martin Larisch
The construction of diaphragm walls and large-diameter bored piles is normally carried out using drilling support fluids to temporarily stabilise the deep excavation prior to concrete placement.
In most cases such drilling fluids are either mineral-based slurries (bentonite), polymer support fluid systems or simply water. The working mechanisms of these three fluid types are fundamentally different.
Even though fluid stabilized deep excavations are often not categorized as temporary works, reliable assessment methods and material specifications for the stability evaluation of such deep excavations are required. Robust design principles for bentonite slurry supported temporary excavations have been developed in the last few decades and the working principles and associated risks of such mineral-based slurries are understood reasonably well. However, polymer supported excavations follow different principles to assess the temporary stability of deep excavations and different assessment methods are required.
The possible fluid related impacts on the permanent design performance of bored piles or other deep foundations need to be considered by permanent works designers to ensure the performance criteria are met.
The webinar also discusses some common construction risks related to the selection of suitable fluid systems for different ground conditions. Typical defects caused by the incorrect application of drilling support fluids, and their pro-active mitigation, are discussed, too.
About the Speaker
Dr Martin Larisch is a Principal Geotechnical Engineer with Jacobs. He has been involved in piling and ground engineering for more than 20 years with technical and operational roles which involved the design and construction of different piling and retention systems for numerous landmark infrastructure and building projects across the Asia Pacific Region.
Martin is also a CPEng with Engineers Australia and has been involved in the development of various industry guidelines and best practice documents for deep foundations in Australia, Europe, North America and New Zealand.