Determination of Pile capacities for piles socketed on fractured rock, with field test data and empirical formulae

Abstract

: The development of tall structures as an uprising trend in Colombo-Sri Lanka is evident during the recent past due to the high land prices. These tall structures require to be founded on strong substrata and piling is the most popular method that has been used as the foundation for these tall buildings. Near the Beira Lake, the authors have noted that the basin consists of highly fractured rock layers and the estimation of the shaft friction and end bearing of piles that rest on these rock conditions are considered to be complex. The capacities are estimated by considering the fracture condition, spacing, weathering profile and also the strength of the intact rock. This envisage that in obtaining the accurate parameters to estimate the pile capacities in such rock conditions, an expert observation is required. This study shares the authors experience in estimating the geotechnical capacity of piles in such rock conditions, to achieve an economical and stable pile foundation system. The empirical formulae used to estimate the shaft friction and end bearing of these piles are discussed extensively in the literature. The study compares these estimated pile capacities obtained from empirical formulae with the field data, for the verification of the estimated capacities. This method can be effectively used for optimizing the pile design to carry specified loading conditions.