EVALUATION OF SHEAR STRENGTH PARAMETERS OF GRAVEL SOILS WITH DIFFERENT SHAPE AND RELATIVE DENSITY

Abstract

This article presents the results of large-scale direct shear tests in laboratory, to evaluate the
parameters of shear strength of remodeled gravel soils at different degree of compaction, with a direct shear
equipment built in the Soil Mechanics Laboratory of the Universidad Nacional de San Antonio Abad del
Cusco, Perú. The cylindrical shear box with 30 cm diameter and 25 cm high, allows testing gravel soils with
maximum size particles of 38.1 mm (1.5"). The four samples of gravel soils evaluated correspond to four
quarries of the Cusco region, classified according to the Unified Soil Classification System as: GP (M-1),
GM (M-2), GW (M-3) and GW (M-4). The tests were developed considering an incremental sequence of
normal load to each sample of 49.0, 98.1 and 196.1 kPa. According to the results, for the four samples tested,
the apparent cohesion was obtained in a range of 19.61 to 64.72 kPa and the internal friction angle in a range
of 35.2° to 52.4°, for the states of relative density very loose, medium and very dense. These results allow us
to conclude that the factors that affect the shear strength of the material are the density and the relative
density of the remolded gravel samples, as well as the fragility at break and the rounded or angular shape of
the soil particles.