Basement Design Proposal, Retaining Walls Design, and Piling Design for Desklib

SOLUTIONS TO THE QUESTIONS
NAME........................................................... ID NO....................................
Part A: Basement Design Proposal
1.0 In choosing the most appropriate construction method for the basement (including
waterproofing method and providing the reasons to feel this is the best choice):
Cofferdam method can be selected in this case:
In this construction method, either a temporary or permanent watertight box is installed around the area in
which the building is to be constructed. Normally it is made from a complex design of steel sheet piling
interlocked and having ground anchors to stabilize the piling system and is done before excavation ensue.
The basement is therefore established from within the box-like structure and waterproofing can easily be
done from outside after which the cofferdam can be removed.
Therefore, this method guarantees the best possible construction experience as: (i) the box-like structure
hold the soil firmly minimizing costs for further ground stabilizers. Besides, (ii) waterproofing can easily
be done after which external backfilling is made possible. (iii) It is also the best method in this area as it
is expected that the area, being in the vicinity of a river, may suffer more water logging challenges hence
this is the best method to minimize water logging problem by providing a permanent shield against such
occurrence.
The waterproofing method
The best combination with the above construction method is the tanking method with mastic asphalt as
the waterproofing material. This method can easily be used in confined spaces as the above given
scenario.
2.0 Choosing the type and number of the excavation plant to be used and providing reasons for
the choices:
Excavation Plant
Type Number Reasons for choice
Backactors 1 Deep trenching for laying of
box-like structure
Face shovels 1 Clear the area and level the
soil within and around the
area
TOTAL 2

Part B: Retaining walls Design
3.0 Stage one
Because you have no previous knowledge of the site you will need to find out all about the
project (specifically the retaining wall details). Prepare a list of questions that you will need
answering before you can prepare your advice:
LIST OF QUESTIONS FOR ANSWERING
(i) Were the retaining walls used adequate in strength to prevent the excessive vertical
displacement that was expected?
(ii) Did the contractor use all the required materials in their correct proportion as was
purportedly directed by the consultant?
(iii) Is the area under active earth pressure and were the engineers in the know? Did they
consider this situation beforehand? If yes, what were the safeguards imposed for this
kind of scenario?
(iv) Did the nature and characteristics of the soil established? If yes, did the safe load
bearing capacity exceeded?
(v) Did the height of water table vehemently featured in the design? How was it
accommodated and was that adequate?
THE ADVICE
Many a time building collapse is mostly caused by inappropriate selection of the right materials
and methods to construct the retaining walls. As provided in the above questions (that need
answering) this unfortunate incident may have been caused by neglecting of the small design
issues that could make a big difference. For instance, inappropriate choice of material can put too
much stress on the weak retaining walls causing subtle failures that would only be manifested
later when the building is trying to ‘settle’ in. Secondly, it is often important that the issue of
establishing the height of water table be vehemently revisited during the pre-design stage. This
would require the engineer to make several site visits in order to establish the true scenario of the
area before undertaking the design. However, sometimes, client’s requirements may be way
above the budget requirements; the engineer-in-charge should always advice the client
accordingly about every aspect of the building construction requirements. Notably, in this case,
and without pre-empting the case direction, it was important for regular review meetings to be
held and the above issues discussed at every stage of construction, at least after every floor was
completed.