Bored Pile Construction Challenges in Highly Variable Limestone for a Supertall Building-Paper

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The paper describes the foundation design and construction for a 77-story tower in Kuala Lumpur, where highly variable karstic limestone made bored-pile installation unusually difficult. The site also includes the Kenny Hill residual soil formation. Limestone conditions ranged from deep cavities and caverns to steep pinnacles and underground ledges, making the rock surface difficult to predict.<br /><br />The tower’s 108 bored piles, 2.0 or 2.2 meters in diameter and up to 100 meters long, were socketed into limestone to support heavy building loads and limit settlement. Design relied on extensive investigation, finite-element modeling, and two full-scale Osterberg-cell load tests. Test results supported a site-specific relationship between rock quality designation (RQD) and socket skin friction. Modeling also informed criteria for defining socket lengths where the rock surface sloped steeply.<br /><br />During construction, each pile location was proof-drilled, and the surrounding rock was pressure-grouted to fill voids and improve stability. Core quality, drilling behavior, cuttings, and shaft inspections informed final pile lengths. Proof-drilling estimates were generally within 5–10 percent of completed pile lengths, though unexpected ledges, cavities, and deep rock sometimes required substantial changes.<br /><br />Construction challenges included unreliable proof-drilling results, collapsing boreholes, sediment accumulation, and polymer slurry deterioration—sometimes worsened by grout entering adjacent open pile shafts. The team responded through close monitoring, revised procedures, and replacement of contaminated slurry. In some locations, piles had to bypass upper rock layers or stop short of the ideal socket depth because of equipment limits; analysis indicated that five shortened piles would not significantly affect overall piled-raft performance.<br /><br />The project’s success depended on phased investigations, load testing, rock grouting, rigorous quality control, and continuous coordination among the owner, designers, engineers, and contractor. The case demonstrates the importance of maintaining design involvement during construction and adapting foundation decisions to actual ground conditions.

Keywords

Kuala Lumpur tower

karstic limestone

bored piles

pile foundation

Osterberg-cell load tests

rock socket

RQD

pressure grouting

proof drilling

piled-raft foundation