Abstract:
The current trend of building skyscrapers in busy urban areas has led to the unique
problem of facilitating deep excavation without disturbing the adjacent structures or roads. This
excavation support should be both Earth retaining as well as Water Excluding. This paper details the
construction of the earth retaining system for the ‘The ONE’ project, located in the heart of CBD
(Colombo Business District), and the challenges encountered. Design of the system is also briefly
discussed. A secant pile wall consisting of 871 piles was constructed to ensure the water tightness.
Inclinometer pipes were installed in the secant pile wall at selected locations to monitor the deflection
of the wall during excavation. Additional pressure grouting was carried to ensure stability of the
adjacent structures. Boundary scanning was carried out to locate the underground utilities to carry out
the temporary ground anchors. In addition to these activities, the paper also briefly discusses the
building health monitoring activities carried out during the project.
