COMPUTER AIDED ESTIMATION OF SETTLEMENT OF PILE GROUPS

Abstract

Allowable load on a pile group is generally governed by settlement criteria rather than bearing failure. Hence the estimation of pile group settlement at design stage is very important. Some of the practices presently adopted for estimation of pile group settlement have been discussed and translated into a computer program to facilitate as easy, quick and efficient solution. The program is of interactive type and applicable to pile groups subjected to simple static vertical loading and founded on (i) cohesive soils, (ii) cohesionlcss soils and (iii) layered soil profile. The program is written in FORTRAN-77 and can be executed in a personal computer. Some typical numerical examples and a case history on settlement of a structure supported by pile groups have been solved to illustrate the use of program. Also some numerical problems for assumed data have been solved to make parametric studies such as the effect of width of pile group, effect of the thickness of sublayer for computation and the effect of variation of soil stiffness with depth on computed settlement. It is observed that the method proposed by De-Beer and Marten (1957) for estimation of settlement of pile group founded on cohesionless soils gives settlement higher than that estimated by Schmertmann's method (1970). The settlement computations carried out by dividing the soil stratum into number of small sublayers show that to obtain reasonably accurate results the compressible soil stratum should be divided into sublayers of thickness at least as small as 0.25 times the width of pile group