Early 2017 a pair of mainland developers agreed to pay a record HK$16.86 billion (RMB 13.75 billion) for a waterfront residential site on the city’s Ap Lei Chau island. The purchase is the single most expensive purchase at a government land sale in Hong Kong’s history, with the price paid exceeding market rates by nearly 50 percent. The oceanfront location of the site, which was formerly used as a driving school, makes it particularly appealing to developers desperate for luxury property opportunity, as the government market curbs appear to be driving investors into high end units. One can imagine the developer wants to have it generate an income as soon as possible!

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. 

The foundation piles had a length of 18-24 meters, length being dependent on the depth of the bedrock. When high grade and heavy steel H-pile section are used, the load carrying capacity can exceed 5500kN per pile. Socketed H-piles are stronger in flexural strength than small diameter bored piles. This type of foundation can also be designed to resist horizontal loads by their bending stiffness.   

Other piling work at Ap Lei Chau included retaining walls. These retaining walls included 600mm casings and 17-meter-long No.4 sheet piles. These were driven with the ICE 815C vibratory hammer along the perimeter of the site.

The main-con for the foundation work is CRBC-BuildKing, with the foundation job sub-contracted to long-term ICE client Zhenxing. 

Zhenxing had several 416L and 815C ICE hammers onsite to drive the 610mm, 15m long casings. In my 7 years with ICE this was the fastest extraction of a casing I’ve ever witnessed. This narrow strip of land hugging the mountains with a stunning view of the sea around Hong Kong island is in a hurry to make a return on investment and ICE equipment is doing its part to make the deadlines.

 If you also have a strict deadline to meet, then contact us today to check if we can be of assistance!