Hong Kong is a small city with a dense population. Due to limited land resources
and dense population, skyscrapers are built to meet the commercial and residential
needs. To fulfill the functional requirements, the superstructure is usually
supported by piles through a thick cap. A bored pile foundation is one of the most
common deep foundation systems with a high capacity adopted in Hong Kong.
Most of those piles are founded on Grade III or better rock. However, as lack of
field experience and high quality database, the behavior of such pile foundation
system is still unclear. These bored piles are designed as the end bearing piles. In
addition, the load distribution among the piles and the load shared by the pile cap
are also not properly addressed in the local design. In order to properly address the
above-mentioned issues related to the design of pile foundation, in particular for
large diameter bored piles, a comprehensive field study was launched.
Furthermore, the numerical simulations were also carried out.
A comprehensive field study was carried out on the behavior of a building
supported by large diameter bored piles. The building (40-storey public housing)
is Y-shaped with three wings (Wing A, Wing B, and Wing C) and a central core
(Central Core). The superstructure is resting on a Y-shaped foundation cap (2.3m
in thickness) which is supported by 18 bored piles (2.2m in diameter). The piles
terminated at Grade III or better rocks. The field test results indicated that the pile
group took up most of the applied load, while the cap had an insignificant
contribution to the capacity of the foundation system. The axial force in the pile
increased from the outer edge to the inner area of the cap. The shaft resistances
mobilized in the soil layer and the rock layer were significant. As a result, the
axial force reduced to a not significant level at the toe.
The finite element model could generally reflect the bored pile deformation and
the load distribution along the pile. The numerical simulation results could
generally reveal the load distribution among the piles. Based on the numerical
analyses, the load distribution among the piles was strongly dependent on the cap
stiffness. Moreover, when some pile stiffness reduced, the applied load will
redistribute among the piles. More loads will transfer to the nearby stiff piles. The
effected region of redistribution in axial force increased with the cap stiffness. / published_or_final_version / Civil Engineering / Master / Master of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174544 |
| Date | January 2011 |
| Creators | Yu, Zhenxiong, 余振雄 |
| Contributors | Tham, LG |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47849861 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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