Pavilion Damansara Heights (Phase 1)

Scope of Works: foundation, retaining wall and basement works

The project site is located within Damansara Heights between 2 MRT stations - Semantan and Pusat Damansara. Phase 1 footprint alone is 9.573 acre. The contract entails the removal of existing foundation of demolished buildings as well as the construction of bored pile foundation, retaining wall system and 8- level basement.

The basement is one of the largest and deepest ever constructed in the region with a massive floor plate area of approximately 300,000m². The total depth from existing ground level to lowest slab is approximately 31m excluding the deepest lift core construction which required another 10m depth of temporary shoring works.

Approximately 900 points of bored piles with diameters ranging from 750mm to 3,000mm were constructed in Kuala Lumpur Kenny Hill formation.

Existing surrounding dense environment and Sprint Highway had precluded the construction of deep basement using conventional open cut method and tie back system using soil nail/ground anchor due to encroachment issue by site boundary.

Top-down construction and semi top-down construction methods where floor slabs are utilised to strut against the deep basement wall while excavating downwards are adopted. The top-down work sequence adopted alternate basement permanent floor (B3, B5 & B7) as strutting slabs against the contiguous bored pile (CBP) basement wall.

Sequence took into consideration of basement slab (including temporary openings to facilitate earth removal and concreting works of lower floors) and CBP wall in modelling, design, logistic and construction work aspects.

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Naga 3 Integrated Entertainment Complex, Phnom Penh, Cambodia

Scope of Works: Piling, Pile cap, Diaphragm Wall, Basement & Associated Works

The project sits on Sangkat Tonle Bassac within the heart of Phnom Penh City and shall consist of 3 towers rest atop a lower podium when completed. The foundation and substructure package entails construction of bored pile foundation, retaining wall system and 4-level of basement.

The site measures 4.62 acre and is located within congested urban environment which comes with inherent construction challenges. 36 borehole investigations were carried out in 2019 to determine the nature and location of different soil or rock layers; followed by construction of 2 preliminary test piles in 2020 to verify design calculations. The soil profile comprises mainly of clay and silt. A high water table is also detected.

Drilling rigs and supporting machinery were mobilised from Malaysia to Cambodia in early 2021 and site works have since commenced.

The project site is divided into 3 main sections and the work package is being carried out in phases across the sections.

With weak ground conditions, deep soil method was used to improve soil in-situ and thus minimising soil settlement along the western boundary adjacent to existing buildings. A total of 1,154 soil mixed columns were installed to a depth of up to 24m covering an area of 1,273m² in mid-2021.

A 778m long diaphragm wall comprising 120 cast in-situ panels with varying sizes and wall thickness between 0.8m to 1.0m were completed in early 2022 to support the soils at the sides prior to deep excavation.

Basement substructure work was kicked into high gear since end of 2021 following the completion of bored piling work in critical areas within Section 1 and Section 2. As at end of October 2022, piling works are ongoing in Section 3, while basement floor slabs are being simultaneously constructed across the site.

With the adoption of top-down construction method, the higher-level floor slabs are being cast before the lower-level slabs, to act as lateral support to the perimeter diaphragm wall as excavation progresses.

The construction activities for basement substructures will continue with increased intensity throughout 2023.

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Sungai Besi-Ulu Kelang Elevated Expressway (SUKE) Package CA3

Scope of Works: foundation, substructure and ancillary works

The contract entails the construction of over 1,000 bored piles and 50 caisson piles for package CA3 starts from CH. 4200 to CH. 7800 with total length of approximately 5.2 km in Alam Damai, southeast of Kuala Lumpur.

This project is of particular engineering importance as it showcases the pioneering expertise in large diameter hard rock drilling using down-the-hole (DTH) hammer in challenging rock formations. With percussion boring, the DTH technique, compared to conventional rotary drilling, has been proven to be significantly more efficient in hard rock areas. DTH hammer was used to drill 200 points of large-diameter bore holes for the project (with 1,200mm∅ and 1,500mm∅ casings through hard granite strata).

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MAS Building Annex Redevelopment

Scope of Works: foundation, retaining wall and basement works

A 37m deep excavation was carried out to construct a 6-level underground basement at Jalan Sultan Ismail in downtown Kuala Lumpur. On top of being situated very close to the Raja Chulan monorail track, the site is located next to a busy road with heavy traffic, high-rise buildings and the existing MAS Building. The project demanded control of minimum lateral wall movement, minimum soil settlement, and timely completion in a very limited site area of about 2,400m².

Major works for phase one included demolition of the front podium and removal of existing 450mm∅ CBPs. Second phase involved installation of new CBPs ranging from 600mm∅ to 1,350mm∅, of an average depth of 45m and 3,000mm∅ foundation bored piles of an average depth of 70m. The semi top-down construction method with kingposts was adopted, in place of installation of temporary steel struts and walers to support deep excavation. 6 basement slabs were constructed and the volume of earthwork was approximately 82,000m³.