Performance of high capacity jack-in pile for high-rise building with preboring in weathered sedimentary rock formation

Abstract

High capacity jack-in piles with working load of up to 3000 kN were successfully designed and constructed for a proposed residential apartment of up to 24-storey high in East Ledang, Nusajaya, Johor, Malaysia. The installation of jack-in pile was carried out after preboring works to ensure a minimum pile length of 5.0 m below cut-off level due to the shallow hard layer (SPT-N > 50) of the weathered sedimentary rock formation. The prebored hole was backfilled with loose soil and jack-in spun pile was installed with termination criteria of minimum two (2) times working load, with the maximum jack-in pressure maintained for at least 20 seconds and the procedure repeated three (3) times for each pile. The termination criteria includes pile head settlement not exceeding 2.0 mm for each pile set / termination reading and the set readings were taken at least three (3) times with an interval of not less than three (3) minutes between each set. The above procedure was adopted to minimize the effect of excess pore-water pressure which may cause premature termination of the pile. The performance of the jack-in pile system was validated based on results of pile static load tests and instrumented test pile. The obtained load test results are discussed in this paper.