EVALUATION OF THE EFFECT OF YIELD SURFACE SHAPE ON STATIC AND DYNAMIC ANALYSES OF GEOTECHNICAL STRUCTURES

In geotechnical engineering, yield surface (criterion) is a subject that has attracted the attention of a large number of researchers in both elds of experimental and constitutive modeling. Various yield surfaces have been introduced by dierent investigators, of which, Mohr- Coulomb and Drager-Prager criteria are the most famous. Generally, yield criteria are used in constitutive model structures. On the other hand, the nal aim is to apply these constitutive models in numerical analyses of geotechnical engineering problems. Therefore, the question which arises here is; how high is the degree of eect of these yielding surfaces on numerical analyses of geotechnical problems, and also, is a more accurate yielding criterion needed or not? In this paper, two constitutive models of MCH and DPH have been introduced in such a way that they have quite similar structures and the only distinction between them is their supposed yield surfaces. In fact, these models have been originated by a combination of the hyperbola model with Mohr-Coulomb and Drager-Prager criteria, respectively. After calibration of the two constitutive models by experimental data on a specic stress path, their performance on other stress paths were also evaluated using laboratory data. Then, using Fish programming language, the two constitutive models were introduced into the FLAC program to enable investigation of various numerical analyses. In this way, performances of these constitutive models and, consequently, the eect of the yield surfaces on the static and dynamic analyses of geotechnical structures (such as foundation bearing capacity, tunnel and excavation), were evaluated. Therefore, a better insight into the degree of eect of various yield surface shapes on numerical analyses of dierent geotechnical problems could be obtained for engineers who use dierent constitutive models for design and numerical investigation, and also for researchers who study constitutive models.