A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
However, the suggestion of provision of nominal reinforcement to cater for
seismic effect may be justified. Reference is made to J P Tyson (1995).
19. How to measure rock during piling operation?
There is no strict rule in governing the measure of rock encountered in
piling operation. There are two common practices in measuring rock during
piling:
(i) Measure the quantity of obstruction taken out from the drilled out;
(ii) Firstly, it is assumed that the rock surface is uniform. Based on this
assumption, measure the obstruction level by using a tape.
20. What are the advantages of using top-down approach in basement
construction?
The advantages of top-down approach are listed below:
(i) The structures above ground can be carried out simultaneously with
the structures below ground. This greatly reduces the time for
construction.
(ii) By using this approach, settlement can be reduced.
(iii) Since the permanent columns and slabs can be utilized to support
loadings during construction, it saves the cost of formwork.
Note: Top-down approach means construction of basement is carried out
from ground level downwards.
21. What are the methods to tackle negative skin friction? (FD12)
(i) Use slender pile sections (e.g. H-pile or precast pile) because smaller
pile area when subject to the same working load would produce
higher deformation, thus increasing the relative downward movement
of piles.
(ii) In a certain region of H-piles for ground water table fluctuation,
painting is applied on the surface of H-piles because the rise and fall
of water table contribute to the corrosion of H-piles. On the other hand,
to reduce the effect of additional loads brought about by negative skin
friction, bitumen is applied on the pile surface corresponding to the
region of soils that has negative skin friction. However, bitumen
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