RSC9 @ Genting
(Permanent Soldier Pile Wall with Soil Nail Tie Back)
(By Ir. Oh Chin Wah, Executive Director and Ms. Carmen Ngio, Design Engineer) (2015 Apr-Jun)
This project involves construction of 1 block 27 storey new staff quarter with 4 level of basement. It is located at Genting highland and partially located at sloping terrain. The proposed foundation design includes 169 number of bored pile, 361 number of micropile and 24 number of hand dug caisson on the existing slope. Due to the urgency to the delivery of the project, the total duration for the foundation is only 4.5 months, including the earthwork excavation and construction of 4 level basement wall. The interesting feature of this challenging project is the design and construction of the basement using permanent soldier pile with soil nail tie back to avoid the deep open excavation and under tight working space which is located along the existing busy main road.
Permanent Soldier Pile Wall with Soil Nail Tie Back along G/L A
The design of this soldier pile wall is to facilitate the temporary excavation of the drain culvert installation, as well as the basement wall excavation up to maximum height of 10m. The original design of open slope excavation is not applicable in this case because of the close proximity to the main road. In order to overcome the slenderness of the soldier pile and to expedite the excavation work, multilayer soil nail tie back was adopted in this case which act as temporary support of the wall before the final strutting from the floor slab.
Soil data and wall analysis results using Plaxis and Slope/w
The existing soil profile is typically granitic formation as shown in the SI borehole results. It consists of backfilled soil of loose to medium sandy silt with boulders from existing ground level approximately 6m- 7m below ground. Beyond that, the soil is ranging from medium to stiff sandy silt until reaching to the rock head with sound granite at about 20m – 25m below the EGL.