Comparison of Soil Properties obtained from In-Situ Tests and Laboratory: Case Study of shallow Foundation

Abstract

– In geotechnical engineering, in-situ penetration tests are widely used for site investigation to support analysis and design. The Standard Penetration Test (SPT) is the most common in-situ test for soil investigations in sandy soils. When it is necessary to expand the scope of investigation, geotechnical engineers typically supplement with a cheaper and quicker method such as the Cone Penetration Test (CPT) and flat dilatometer test (DMT). These tests are routinely used in geotechnical evaluations and are considered adequate for detailing soil profiles and determining soil properties. However, the correlation between the results of CPT, DMT, and soil properties is not well established yet. In this work, ground characterization and estimation of soil properties based on the combined use of in-situ tests included SPT, CPT, and DMT along with laboratory tests were conducted and evaluated. The evaluation of in-situ tests in terms of soil type, unit weight, elastic modulus, and friction angle was compared with laboratory results. To achieve the presented objectives, field and laboratory investigations were performed on a case study of shallow foundation design using general bearing capacity equation. For satisfactory design, the design must satisfy the shear and settlement criteria. These two criteria are independent to each other and must be satisfied. As results, the findings from in-situ and laboratory tests did not agree in terms of settlement calculations. The predicted bearing capacity of the case study estimated size against general failure from 1 m to 1.3m. However, the estimated settlements exceed the allowable limits, and therefore the foundation dimensions had to be suitably modified to settlement criteria.