抄録
This paper presents a method to extend an elastoplastic constitutive model valid only in the triaxial compression condition to one applicable in general stress conditions. A stress-strain model in three-dimensional stresses was developed on the basis of the extended concept of the "Spatial Mobilized Plane" (briefly SMP*). From reconsideration of the concept of theSMP*, a mechanical quantity to describe uniquely the behavior of soils in three-dimensional stresses is obtained. This mechanical quantity tij is a symmetrical tensor whose each principal value is the product of the corresponding principal stress and the corresponding direction cosine of the SMP. The mechanical quantity is then applied to the Cam-clay model as an example. It is checked by various data of drained and undrained shear tests on normally consolidated clay that the tij Cam-clay model proposed here describes uniquely the behavior of soils not only under the triaxial compression condition but also under the triaxial extension and three different principal stress conditions. Although only the application of tij to the Cam-clay model is shown in this paper, tij is easily applicable to any other elastoplastic constitutive models for soils.
