A CRITICAL APPRAISAL OF IS CODE RECOMMENDATIONS ON SAFE CAPACITY OF UNDERREAMED PILES

Abstract

Underreamed pile foundations have found a very wide use in India as a form of foundation on difficult soil conditions (foundations on swelling soils, foundations subject to high uplift loading. ). The cost involved in pile foundations is considerable. Saving a few percent of these cost by reliable estimate of allowable bearing capacity of a pile will effect considerable economy. The Indian standard code of practice IS:2911 part (I•II) 1973 recommends a Table' of safe capacity values, which are reported to have been obtained from the results of field tests on underreamed piles. These recommended values are considered valid for certain range of soil properties (for example angle of Internal friction in sands varying from 300 to 36° and cohesion in clays, varying from 0.25 kg/cm2 to 0.5 kg/cm2). The present study undertakes to utilize well established soil mechanics and other Engineering methods to compute safe capacities for the soil and pile conditions specified by the Code and evaluate the adequacy of values tabulated in Code......