In bored pile construction , there are few widely spread methods in stabilizing the bored hole. This post discusses these methods in summary.
The most common and economical solution is to use bentonite
and the main idea behind using bentonite is to stabilize the bored hole. Owing to
the high density, it prevents water inflow to the hole. However, if it is a floating
pile or depend significantly on skin friction to resist load then the use of
bentonite is controversial.
If bentonite is not the solution then the next economical
solution is to use temporary casing. Steel
casings are widely used in the industry. However extraction of the casing
during the construction is challenging explicitly in deeper depths.
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| Inserting a temporary steel casing- checking for versatility of the steel casing using the buble |
In that case you can decide for permanent casing and it has
to be ensure that you have considered
the cost allocation for that. This can be decided with the specialized pile
contractor.
The mix design of the
concrete using for piles also play a pivotal role and there are many
specification on this subject. BS 6235,ACI 357,Dnv are few of them…
Generally cement water ratio is around 0.4 for the submerged and minimum cement content
would be 360 kN/m3. Minimum 28 days characteristic strength would be 35 N/mm2. Of
course these are general specification and designer has the authority to adopt
tailor made solution. The Portland cement is preferable and low content of tri calcium aluminate is preferable to reduce
the risk of sulfates attacks, if it is offshore construction explicitly.
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| RF cages for insertion |
