Construction work is already in full swing. The developer selected socketed H-piles for their foundation design. This method is popular in Hong Kong as it well suited to local soil conditions. Hong Kong soil conditions are often a mix of backfill, followed by sandy or clay layers and finally reaches bedrock. Socketed H-piles are made by inserting a steel H-pile section into a pre-bored hole in rock. The hole should have a diameter adequate to accommodate the steel section. A protective casing is often vibrated and later extracted to facilitate the drilling of the hole. At Ap Lei the 65t driving force 416L was chosen for the driving and extracting of this casing.
The 550mm bore diameter requires the support casing to have an outer diameter of 610mm, the protective casing length was 15 meters long. The H-pile section can be placed directly on the rock surface of the pre-bored hole. The hole is then filled with non-shrink cement grout.