Assessment of pile failures due to excessive settlement during pile load test

There are around 10 major bridges are being under construction in the Nagapattinam Tiruthuraipoondi B.G railway line. These bridges are supported by pile foundations with varying founding depths depending up on the soil stratum. Bored cast in suit piles were cast and pile load tests were conducted at five locations for the estimated pile capacity (capacity was estimated as per IS 2911). Almost in all the locations, the pile load test were failed, which means the pile settlement was beyond the specified settlement under the test load. The failure was assessed and reported in this paper. The estimated pile capacity (design load) and test load (working pile load test) was 278MT and 417MT respectively. The pile has got yielded (settled) beyond 12mm, when the test loads of 220MT (which is 80% of the working load) in progress. The pile got settled around 25mm when the working load was in progress and finally reached to 38mm after 12hrs. After unloading, the pile has got rebound only 3mm, which motivate us to do the complete re-assessment of the soil strata in the study area. The forensic investigation on this failure has clearly evident that the failure had happen due to inadequate geotechnical investigation and improper pile installation. The cause will be discussed in this paper.