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7/28/2019 [CCH] BST22316 2012_2013 Sem B RW Assignment
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Semester B, 2012/2013
BST 22316
Construction Technology
Lecturer:
Mr. WONG Wai Man Raymond
Individual Assignment
Student Name: Cheung Chun Hin
Student I.D.: 52999911
Hand-in date: April 2, 2013
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Table of Content
1. Introductions / Assumptions / Overall View2. Stage 1 - Ground Stabilization Provisions3. Stage 2 - Cut-off Walling Provisions/Lateral Soil4. Support Provisions5. Stage 3 - Excavation Arrangement6. Stage 4 - Dewatering Arrangement7. Stage 5 - Spoil Removal Arrangement8. Stage 6 - Basement Construction Arrangement9. Conclusion10.References
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1.Introductions / Assumptions / Overall View1.1 Abstract
In building a deep and large-size basement, there are various elements and
considerations such as labor, space, material, machineries, basement design
requirement, etc. As for a successful project, a proper arrangement and control
is important, therefore we will focus on situation analysis, make appropriate
approach and problem solving methods in the each of the following parts.
In this report, there will be mainly focus on the basement construction with the
6-7 principle steps. By illustration of diagram and photos taken by me, it would
be explained in detail about the actual steps of construction sites and material
types. More than learning in text book through theories, it is learning in a more
realistic method and manner.
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Nature & Purposes
Project Aims: This project is to build up a building with a deep and large basement
1.2 Master Flow Chat
1.3 Common managerial problems identified in the construction of deep basement:1. Very expensive and time consuming in nature, often involved
huge amount of work resources.
2. Inconsistent and sensitive to the quality of planning and
management of individual projects.
3. Works are highly hazardous, both to human operatives
working within and the life and properties of third parties that
within the vicinity.
4. Works involved a lot of managerial challenges. Such as, in
the preparation of a highly efficient working programme,
monitoring and rectifying the progress of works in case
problems arising, or in resources planning where materials,
labours & plant equipment are involved.
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2.Stage 1 - Ground Stabilization Provisions2.1 Purpose
There are mainly 3 functions for ground stabilization, including strengthens
improvement (increase load-bearing capacity of soil), dust control (alleviate
dust generated by machinery operations), and soil waterproofing (to increase
waterproofing ability of soil from surface)
2.2 Situation AnalysisGiven that the site is large in size and the soil in weaker in nature, the main
function for ground stabilization is to strengthen soil load bearing capacity so
that the soil have sufficient stability to support the loading from the building(dead-load) and users (live load).
2.3 Possible Methods & ChoiceThe method of soil stabilization is broadly divided into 2 approaches, chemical
soil stabilization and mechanical soil stabilization. In Hong Kong, there is
mainly using grouting which is under chemical soil stabilization approach
1. Add quicklime / hydrated limeMechanism: absorb the water / moisture in soil
Advantages: easy transportation, cheap
Considerations: cannot reach deep underground, time-consuming
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2. Fly ashMechanism: reduce the air voids
Advantages: easy transportation, cheap
Considerations: cannot reach deep underground, time-consuming
3. GroutingMechanism: reduce the air voids, control water fillings, prevent sand
deification, reduce vibration, and reduce settlement.
Advantages: numerous varieties of functions, stable, effective
Considerations: comparatively expensive
Recommendation
Among the above options, it is recommended to take grouting as the way to
stabilize the ground, because it is relatively efficient, reliably stable.
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2.4 SequenceCement grout is formed by mixing water, cement, sand in a proper ratio (typical
proportion by weight is 1:0.5:3). It is intended that cement mortar is
constructed by placing, packing, or pressure pouring. Owing to the relatively
high water content, the mixing of cement with water produces a fluid
suspension which can be poured under base plates or into holes. Then to wait
some days for setting and hardening, this process is to create a good
performance. After the grouting is finished, a substantial proportion of load is
designed to be transferred by the bedding to other members.
2.5 Considerations of this Method2.5.1 Rainy weather may lengthen the time-requirement for setting, weaken or
even damage the grouting.2.5.2 Strong sunlight may damage the grouting quality2.5.3 It is necessary to control the voids in the soil, because excessive voids may
affect the strength, stiffness and permeability of grout
2.6 Solutions2.6.1 Ensure the soil quality by civil engineer2.6.2 Prepare the project time properly in avoid construction within rainy seasons.Calculate the mixture ratio of grouting carefully based on the soil data, and add other
chemicals whenever necessary.
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3.Stage 2 - Cut-off Walling Provisions/Lateral SoilSupport Provisions
3.1 PurposeTo withstand the lateral loading of the site, so that the site can be safe when
constructing basement or other works.
3.2 Situation AnalysisWe assumed that the soil is bad graded and soil content is wet in nature. There
are adjacent buildings nearby. We should consider the spacing and the sufficient
support to the side force.
3.3 Possible Methods & ChoiceThere are many ways to construct a cut-off wall. Despite of the methods are so
many, there are commonly 6 types of practices in Hong Kong which are as
follow:
1. Steel pile
[Photo taken ME @ 1/4/2013 Wu Hu Street]
Advantages: resist tension
Considerations: rusting may occur
STEEL PILE
Lateral Support
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2. Soldier pile
[Drawn by Me]
Advantages: reusable, reliable, relatively cheaper than steel pile
Considerations: rusting may occur, require accuracy jointing
3. Hand-dug caisson
Advantages: cheaper cost
Considerations: very dangerous to workers life
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4. Bore pile
Advantages: very stable
Considerations: expensive, permanent
5. Mini-pile or pipe pile
Advantages: suitable for small or medium construction site
Considerations: rusting may occur, limited to 12m depth
6. Diaphragm wall
Advantages: fully supported
Considerations: require more complex procedure and more support system
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Recommendation
After the choosing the above choices, it is better to use diaphragm wall with
steel struts and diagonal bracing in this situation (but not using anchor),
because it support deep excavation without using other underground
spacing.
Elevation:
[Photo taken by ME@1/4/2013 Intercontinental Hong Kong expansion work]
Illustration Drawings [Drawn by Me]:
Section:
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NOT USING ANCHOR (because buildings nearby)
[Photo taken ME @ 1/4/2013 Chatham Road North]
3.4 Case Example
Just like the basement work in Intercontinental Hong Kong expansion work
Anchors
Increase the slope stability
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() which owned by the New World Development
Company Limited. The basement used the diaphragm wall with lateral
supported by the steel struts and diagonal bracing. It is a common and
economic method which broadly adopted in large site construction.
3.5 Considerations of this Method1. Require more complex procedure2. Need more spacing3. Preparations require more time
3.6 Solutions1. Recruit more skilled labor2. Carefully planning the site spacing and use more
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4.Stage 3 - Excavation Arrangement4.1 Purpose
Before building a new structure at a specific site, excavation of the original spoil
above or below the ground is needed so that the building works are process
properly. There are several considering factors which are as follow:
1. Nature of subsoil affect type of machine used and the necessity of soilprotection.
2. Size of excavation affect type of machine used and method to excavate.3. Scale of work large volume of excavation may involve complicated phasing
arrangement and work planning
4. Ground water condition affect degree of protection (watertight sheetpiling or dewatering may require)
5. Surrounding condition impose certain restrictions and precautions (e.g.diversion of a government drain, or underpinning work to the nearby
building foundation)
6. Depth of excavation affect use of spacing and working platform4.2 Situation Analysis
In this site, the subsoil is loosely compacted, not much rock and there isnecessary to strengthen the soil. Since the site is large enough, large machines
with higher efficiency are available in use. In building a deep basement,
excavation machines are needed to work at the bottom of the designated site
with different level at each of the time. So, when the basement is not deep,
there would only need to use simple excavation machines; but when it is deep
enough, it would necessary to use machines support long distance carrying.
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4.3 RecommendationIt is recommended to take excavation in a way ofbencharrangement for open
site. Firstly, it excavate the central part of soil and make it similar to open-cut
method. Then it forms slopes at the surroundings and excavate the soil at the
side after the central part is clear. This is a pattern that the site would be
excavating into a shape like bench when we looking at the top of the site. This
has an advantage that the remaining soil can act as a support at the corners
while there is sufficient spacing provided for operation of work. About the edge
of the remaining soil, it would be good enough to have cut edge with step or
edge of cut, because these 2 shapes are safety enough. Even there is a heavy
rain, it would not easily collapse or slide down.
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5.Stage 4 - Dewatering Arrangement5.1 Purpose
It is a process to remove the over-saturated water in ground and keep the
subsoil within a non-saturated condition.
5.2 Situation AnalysisWe assume that there is no underground river crossing the expected working
space, high water table and there is a need of dewatering. In this case, we are
going to build a deep and large size basement, therefore we should dewatering
as a way to lower pore pressure in soil and avoid causing any damages by base
heave.
5.3 Possible Methods & ChoiceIn total there are 3 methods in dewatering, including:
[Active drainage method]
Dewateringby deep wells
Dewatering by wellpoints &
[Passive drainage method]
Dewatering by horizontal drainage.
1. Dewatering by deep wells
Advantages: drain large amount of water at a time
Disadvantages: uneven drainage over the whole construction site
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2. Dewatering by wellpoints
Advantages: very flexible arrangement, occupied less area
Disadvantages: not as efficient as the above method
3. Dewatering by horizontal drainage (e.g. sump pit)
Advantages: no need to exclusively excavate
Disadvantages: working condition is poorer, passive
Recommendation
After analysis the above methods, we will choose to take dewatering method
by well points. Because the site condition is assumed to have no underground
river which no need to drain large amount of water, but needed to drain evenly
over the whole site. Whenever necessary, we should also use dewatering by
horizontal drainage.
5.4 Precautions5.4.1 It has to be ensure the depth, number, distribution of wellpoints are
appropriate
5.4.2 The use of horizontal drainage should be ready when site level reached theoriginal water table level
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6.Stage 5 - Spoil Removal Arrangement6.1 Purpose
There are always spoils created by excavation, ground displacement work,
in-suit materials, etc. In order to protect the adjacent environment and to cope
with the regulations, it is necessary to remove the spoils in a proper method. In
addition, there are some special materials requires special treatment before
discharge (e.g. Asbestos). Therefore, it is undoubtedly that even removal
requires a plan.
6.2 Situation AnalysisIn the construction of a basement, there would probably have the followingspoils:
1. Soil2. Concrete materials3. Sewage4. Temporary non-reusable structures5. DustBut in the above, we will focus on soil removal arrangement. Because soil takes
the largest portion of spoil in nearly every site. When in considering soil removalmethod, we would make decision on using what types of excavator and why to
use them.
6.3 Possible Methods & ChoiceThere are many types of excavator, including:
1. Compact excavator [Photos taken by ME @1/4/2013 Chatham Road North]
Advantages: higher mobility
Disadvantages: lower weight can be carried (0.7-0.8 tones)
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2. Dragline excavator [Photo taken by ME@1/4/2013 Intercontinental Hong Kong expansion work]
Advantages: Able to transport 168 meters and 450 tones material
Disadvantages: extremely high capital cost
3. Long reach excavator
Advantages: support distance away carriage
Disadvantages: (same with Compact excavator)
4. Steam shovel
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Advantages: allow to install on the train
Disadvantages: Uncommon to be use
5. Power shovel
Advantages: very powerful in harrying weight
Disadvantages: not applicable in all types of construction
Recommendation
From the analysis of the above excavators, we decided that Compact excavator
and Dragline excavator will be used in the construction work. There will be
around 10 compact excavator working at the basement site and cooperativelywork with dragline excavator at the upper level of the site.
6.4 Considerations of this Method6.4.1 Accidents maybe happen during lifting the soil upwards6.4.2 Spacing is important for accessing6.4.3 Air pollution is serious in the site6.4.4 Air pollution and noise pollution may affects the surroundings6.5 Solutions6.5.1 All workers should equipped with safety protective equipment and supervise
by experienced manager
6.5.2 Keep area tidy6.5.3 Improve air ventilation of te site6.5.4 Cover the working site area with plastic curtain
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7.Stage 6 - Basement Construction Arrangement7.1 Purpose
Illustrate basement construction method within the common choice of
Open-cut arrangement, Bottom-up arrangement, Top-up arrangement
with considerations of efficiency and economy.
7.2 Situation AnalysisAs information given, the proposed basement site is large in size and deep.
Therefore 4 points can be deduced as follows:
1. Numerous large machineries are supported to work at the same time2. The lateral support is heavy3. Basement works working time requirement proportionally larger than
normal site, as in accounting the whole project time requirement
4. The basement can support complex construction environment5. System formwork may be used if the spacing can appropriately handled
7.3 Possible Methods & ChoiceConsidering using which of the methods in basement construction, factors like
construction environment, machineries, spacing and spoiling removal methodsare important and the following table shows the major comparison with each of
the methods.
Open- Cut
Top-down Bottom-up
Size of site Very large Large Medium to small
Site environment Unobstructed Adaptable to most
environment
Adaptable to most
complex environment
Lateral Protection Minimum Limited shoring
support
Complex lateral
support
Machineries
Support
All size
machinery
Only small size
machinery
All size machinery
Space provision Not much Not much Temporary vertical
support is needed
Spoil removal
method
Most Limited Limited, but more
choice
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Recommendation
After comparing 3 common practices in Hong Kong, it is affirmative that
Top-down method is the most appropriate one among the choices. The
reasons are as follow:
1. Support above ground construction carried out simultaneously2. Save the cost of formwork3. Settlement can be reduced4. Less time requirement
[Drawn by ME]
7.4
Considerations of this Method1. Accurate cost analysis or work study is difficult to carry out for there is
limited commonality to make comparisons.
2. A great number of random and uncontrollable variances are likely to ariseduring the courses of work. This makes planning and scheduling almost
cannot be exact.
3. The actual effectiveness of works is highly depended on the as-constructedsite environments.
4. Quality of the management and the executing parties, as well as theproblems solving ability of the frontline personnel, also seriously affects the
performance and effectiveness of works.
7.5 Problem Solutions1. Collecting the material data from the market and make use of bulk purchase
when prices are low, properly manage use of material and avoid wastage.
2. Make thoughtful building plan before the start of work3. Keep area tidy by place unnecessary equipment away the working area4. Recruit skilled managers and workers
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8.Conclusion
After the above 6-7 involvement principle, we can conclude that theconsiderations are broadly classified as cost, materials, working method, time, design,
structural properties and management. It is the utmost consideration of construction
in Hong Kong that, time and conveniences are more an essential factors in the whole
working process because the income on sales or rental of the building is a large
amount of pays, compared to the cost of constructing it.
Another point is that, compared to the past years, safety concerns are arising its
importance to any of the constructions in Hong Kong. In the past, building basement
is a difficult and dangerous job as accidents may frequently appeared, particularly
the cut-off method called Hand-dug Caisson1. This kind of method is extremely
dangerous as anything dropped into the hole almost killed the man as there are no
where he can escape. Therefore, I have check online and discovered that, it has been
strictly discourage and even prohibited to be applied in Hong Kong, unless it is
proved that no other way to construct without using this method and have a
convincing evidence about the safety in applying this method.
1Refer to Reference No. 6
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9.ReferencesWEB SITE
1. Basement Construction in Bottom-Up Methodhttp://deltacorp.vn/index.php?option=com_content&view=article&id=191&Itemi
d=340&lang=en
2. Construction of basement in Top-Down methodhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Ata
ng-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Ite
mid=339&lang=en
3. Essential Health and Safe Tips in Basement Constructionhttp://www.hse.gov.uk/pubns/cis66.pdf
4. Goodwood Residence Basement Construction Sequence by Steve R. Nebreshttp://www.authorstream.com/Presentation/stevenebres-598273-basement-con
struction-sequence/
5. Deep Underground Basements for Major Urban Building Constructionhttp://www.nicholsonconstruction.com/techresources/techPapers/PDF/Deep%2
0Underground%20Basements%20Final%20with%20edits%20-%2010-14-03.pdf
6. Hand-dug Caissonhttp://www.safetypartnering.com/smd/inside_c4_c.htm
7. Introduction to Soil Stabilizationhttp://china.cat.com/cda/files/408341/7/Soil%2520Stabilization%2520QEDQ122
9.pdf
BOOK
1. Puller, M., (1996), Deep Excavations: A Practical Manual, London: Thomas TelfordLtd.
http://deltacorp.vn/index.php?option=com_content&view=article&id=191&Itemid=340&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=191&Itemid=340&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=191&Itemid=340&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://www.hse.gov.uk/pubns/cis66.pdfhttp://www.hse.gov.uk/pubns/cis66.pdfhttp://www.authorstream.com/Presentation/stevenebres-598273-basement-construction-sequence/http://www.authorstream.com/Presentation/stevenebres-598273-basement-construction-sequence/http://www.authorstream.com/Presentation/stevenebres-598273-basement-construction-sequence/http://www.nicholsonconstruction.com/techresources/techPapers/PDF/Deep%20Underground%20Basements%20Final%20with%20edits%20-%2010-14-03.pdfhttp://www.nicholsonconstruction.com/techresources/techPapers/PDF/Deep%20Underground%20Basements%20Final%20with%20edits%20-%2010-14-03.pdfhttp://www.nicholsonconstruction.com/techresources/techPapers/PDF/Deep%20Underground%20Basements%20Final%20with%20edits%20-%2010-14-03.pdfhttp://www.safetypartnering.com/smd/inside_c4_c.htmhttp://www.safetypartnering.com/smd/inside_c4_c.htmhttp://china.cat.com/cda/files/408341/7/Soil%2520Stabilization%2520QEDQ1229.pdfhttp://china.cat.com/cda/files/408341/7/Soil%2520Stabilization%2520QEDQ1229.pdfhttp://china.cat.com/cda/files/408341/7/Soil%2520Stabilization%2520QEDQ1229.pdfhttp://china.cat.com/cda/files/408341/7/Soil%2520Stabilization%2520QEDQ1229.pdfhttp://china.cat.com/cda/files/408341/7/Soil%2520Stabilization%2520QEDQ1229.pdfhttp://www.safetypartnering.com/smd/inside_c4_c.htmhttp://www.nicholsonconstruction.com/techresources/techPapers/PDF/Deep%20Underground%20Basements%20Final%20with%20edits%20-%2010-14-03.pdfhttp://www.nicholsonconstruction.com/techresources/techPapers/PDF/Deep%20Underground%20Basements%20Final%20with%20edits%20-%2010-14-03.pdfhttp://www.authorstream.com/Presentation/stevenebres-598273-basement-construction-sequence/http://www.authorstream.com/Presentation/stevenebres-598273-basement-construction-sequence/http://www.hse.gov.uk/pubns/cis66.pdfhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=192%3Atang-ham-theo-phuong-phap-top-down&catid=72%3Acong-ngh-mi-ang-ap-dng&Itemid=339&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=191&Itemid=340&lang=enhttp://deltacorp.vn/index.php?option=com_content&view=article&id=191&Itemid=340&lang=en