Effect of Normal Stress and Relative Compaction on Shear Strength Parameters of Cohesionless Soils

摘要

In most of geotechnical projects linear Mohr-Coulomb envelope is used. In fact, aforementioned envelope is curved forcoarse-grained soils and is affected by some factors such as confining pressure and normal stress. The curved strength envelopecould be used to study the behavior of deep foundations, earth dams, soil slopes, and the other earth structures in which failureoccurs under considerable normal stresses. A deep failure surface may be more critical than a shallow surface when the phenomenonof curved strength envelope is considered, because in fact the internal friction angle decreases with increasing the depth of soil layersand confining pressure. The main purpose of this research is to express the internal friction angle of sands as a function of normalstress and relative compaction. In this study, direct shear tests are performed on air dried and saturated sand samples at differentnormal stresses to evaluate the variation of internal friction angle with these factors.