Stress-Strain Behavior of Sand in Plane Strain Compression, Extension and Cyclic Loading Tests

Abstract

Stress-strain behavior of sand in plane strain compression, extension and cyclic loading was studied. To attain plane strain extension stress states in a conventional plane strain compression apparatus, a pair of intermediate confining platens were added between the specimen and the conventional confining platens. They together were enveloped within a specimen membrane so that the intermediate principal stress can be larger than the vertical stress under plane strain extension stress conditions with the lateral confining pressure larger than the vertical stress. To simulate active and passive earth pressure conditions and those under horizontal cyclic loading conditions with the constant vertical stress in the field, specimens were rotated by 90 degrees before each test so that the horizontal stress when the specimen was prepared became the vertical stress in the test. Typical stress-strain relationships are presented from tests performed on saturated specimens of air-pluviated Toyoura sand measuring strains locally. It is shown that although the relationships between the vertical stress and the vertical strain are considerably non-symmetric about the neutral stress condition under the plane strain compression and extension stress conditions, those between sin and the shear strain are essentially symmetric, and therefore, relevant for modeling. Stress-dilatancy relationships are also presented.