In coarse grained soils, often the allowable strength of foundation system is governed by settlements rather than shear strength of foundation soils. Hence, deriving the modulus of elasticity (E) of subsoil to evaluate the settlement below the foundation is one of the key tasks to decide the size of foundation as well as type of foundation. Numerous methods are available to arrive the modulus of elasticity viz. laboratory and field test (direct measurement-PMT/DMT and plate load test), correlations with SPT and CPT, empirical methods etc. In this paper, we attempted to correlate the modulus of elasticity values derived from in-situ footing load tests with available empirical equations, finite element methods (PLAXIS) and one-dimensional
analysis using SETTLE3D. The ratio of measured ‘E’ (from field tests) with respect to the inferred ‘E’ using different empirical correlations with SPT ‘N’ values is ranging from 0.8 to 9.3 times. The derived ‘E’ values from footing load tests is compared with available software tools, namely PLAXIS-3D and SETTLE3D. The settlement from SETTLE program is slightly higher than the field measured settlement, whereas finite element analysis produced significantly higher settlement than SETTLE program and measured settlement at field.
Subjects: footing load test, modulus of elasticity, settlement, finite element method, elastic theory, Settle
Author: Vinay Kumar M. and Suresh Kumar Gupta P.