2.1 Introduction
The T.T.T. Building has a system of hand-dug caissons foundation. There are a total of 25 caissons of diameter ranging from 1.2m to 2.2m. All the caissons are more than 20m deep to sit on completely or hightly decompsed granite soil stratum with a N-value of not less than, say 200, which are designed for a soil bearing capacity not exceeding 1000 kPa.
Hand-dug caissons are quite dangerous. However, they are used for several seasons. Due to the sloping of the site, it is difficult and costly to set up large machines that can be used for the construction of other types of foundations. Besides, the hand-dug caissons can be done without much noise so that there would not be much disturbances to students in the campus and those living in the Swire Hall.
It is noted that the design and construction of caissons are to comply with Building ( construction ) Regulation 1990 and all cassions are to be constructed in accordance with and Safety Precautions.
Hand-dug
Caisson foundation in progress
