Abstract

In project of applied geotechnical engineering it is necessary to know the shearing characteristics of the soil in place. In some cases, it is not possible to recover intact samples, maintaining their representative mechanical properties and analyzing them in the laboratory. It is, therefore, necessary to carry out tests in situ to determine the mechanical characteristics of soil that are essential to project design. This article reports a practical case study on alluvial sediments with a coarse gravel sandy texture. For its appropriate analysis a large in situ direct shear test has been designed and performed. This technique identified the presence of a weak soil cementation by natural calcite and its important effect on geotechnical soil failure behavior. Moreover, the test stated the unusual shear characteristics for a granular soil-structure of alluvial origin, and the proper cohesion and friction angle values (C=36.9 kPa; ϕ= 52°) to consider in the project.

Keywords: In situ direct shear test; Gravel granular material; Natural cemented soil; Geo Identity Research