Codal Provisions for Foundation Design on Soils and Rocks: A Review

Abstract

Usual design of building foundations is performed based on prescribed serviceability and strength criteria as laid down by various standard codes adopted by different countries. Generally, the total settlement of a foundation is described under the serviceability criterion; whereas a strength criterion is described by bearing capacity of the soil or rock underlying the foundation. Both of these safeguard a foundation from its stability and structural integrity point of view against the acting design loads that may appear during its lifetime. The important most function of a foundation is to transfer super-structure load to the underlying strata which are composed of either soil or rock or both in layers. Engineering properties of both soils and rocks vary geo-spatially in small to large scale. In view of the wide spectrum of soil/rock characteristics, the analysis and design of foundations are provided by understanding of basic soil and rock mechanics principles. Although a detailed analysis of site-specific solutions is a must for a vital and large-scale project as well as for a problematic site condition. Building codes present the most relevant guidance in design and construction of foundations. An attempt has, therefore, been made in the present study to revisit and compare foundation design methodology, by studying and investigating three popular design codes, namely Indian Standard Code (IS code), American Concrete Institute Code (ACI) and International Building Code (IBC) by the International Code Council (ICC). In this study, the basic technical information on (i) ‘general behavior of soil and rock,’ i.e., nature of soil, rock types, stability and properties along with its behavior under foundation, (ii) ‘effect of groundwater,’ i.e., the effect of underground water on foundation, (iii) ‘foundation settlement,’ i.e., foundation failure modes, (iv) ‘preventive and strengthening measures,’ i.e., improvement of bearing capacity of strata through stabilizing methods, etc., have been covered in brief.