Empirical Correlation Between Ultimate Bearing Capacity Of Shallow Foundation And Field Dynamic Cone Penetration Index For Short Term Loading.

Abstract

Bearing capacity is one of the important parameters to be investigated for design and construction of foundations of civil engineering structures. The conventional method of estimating these parameters is relatively expensive and time consuming specially for small scale projects. Dynamic cone penetrometer (DCP) is one of the in situ test methods widely used in site investigation for estimating the strength and density of soils. This work is, therefore, aimed at predicting ultimate bearing capacity (Qult) of shallow foundations from field dynamic cone penetration index DCPI (mm/blow). The soil index properties and tri-axial tests were performed on soil samples extracted from different pits. On the same pits, DCP test have been performed in the field to determine DCPI (mm/blow). Then single regression analysis have been performed to determine relationship of Qult with DCPI and index properties. Single regression analyses results showed that Qult have strong relation with DCPI (R2=0.75) than index properties. The comparison between the developed equation and the actual Qult obtained from Terzagi’s bearing capacity equation shows average variations of ±11.7%, suggesting the validity of the developed equation. The footing dimension have little effect on the predicted bearing capacity of foundation as the variation in bearing capacities with width of footing is very small.