Uncertainty of Measurement of Geotechnical Parameters of a Lateritic Soil

Determination of properties of foundation soil is an essential and indispensable part of any construction activity. However, mining of the geotechnical parameters is a challenging task requiring both a sound judgment and a vast experience. There are numerous uncertainties present in the field of geotechnical engineering due to various kinds of sources. Therefore, the degree of uncertainty arising from sources generally depends on various factors like variability of the soil profile at the site, equipment used, procedure maintained during the testing, and tests carried out by person. Uncertainty that is too large may affect reliability of the decision and make the situation more complex. Hence, it is more important to estimate the uncertainty of measurement. In this study, an attempt has been made to apply the NABL procedure for the estimation of uncertainty measurements for geotechnical parameters of a lateritic soil. The tests were repeated for five times to assess the uncertainty. The soil tests carried out in laboratory were compared with tests performed in NABL-accredited laboratory. The uncertainty for liquid limit, plastic limit, optimum moisture content, maximum dry density, angle of internal friction, and cohesion was determined to be 2.51 ± 0.02, 33.11% ± 0.79%, 23.31% ± 1.98%, 16.39% ± 0.06%, 1.67gm/cc ± 0.09 gm/cc, 20.60 ̊ ± 1.16 ̊, and 0.12 kg/cm2 ± 0.03 kg/cm2, respectively.