Constitutive model for three-dimensional behavior of anisotropic soils | |
| Author | Rizardo, Erwin Lara |
| Call Number | AIT Thesis no. GE-99-14 |
| Subject(s) | Soils--Testing Strains and stresses Anisotropy |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-99-14 |
| Abstract | Recent investigations have gradually elucidated that the rotation of principal stress axes, which is commonly encountered in the in-situ ground, exerts a remarkable influence on the deformation strength characteristics of cohesionless soils (e.g. Arthur et al., 1980; Ishihara and Towhata, 1983; Towhata and Ishihara, 1985b and c; Symes et al., 1982 and 1984 ). Miura et al. ( 1986) have performed a series of drained tests on Toyoura sand by using hollow cylindrical specimens and pointed out the importance of the effects of the rotation of principal stress direction on the deformation behavior of sand. Inherent anisotropy on the mechanical properties of sand, which is induced during deposition of sand particles in the specimen preparation process has notable effect on shear strength, shear deformation and dilatancy behaviors. Shear strength and shear stiffness are both maximum at principal stress direction 2a equal to o0 and minimum at 2a equal to 150°. Due to the inherent anisotropy, strain path tends to shift to the direction of principal strain direction, 2a equal to 90° or - 90° that corresponds to simple shear deformation due to the dominant shear deformation on the horizontal potential sliding plane. The induced anisotropy of sand has notable influence on shear behavior and dilatancy behavior observed in the reloading process after preshearing. However, its influence on shear strength is insignificant. Shear strain and volumetric strain generated in the reloading process increases and decreases, respectively due to preshearing depending on the relative direction of principal stress. The intensity of the induced anisotropy is associated with the amount of shear strain more than that with the shear stress ratio mobilized during preshearing. The constitutive model named as "Multi-Directional Sliding Model" is applied to the deformation-strength characteristics of sand with anisotropic mechanical properties in general three-dimensional stress condition. Its applicability and influence on inherent and induced anisotropy is examined and the following results are obtained. First, the model tends to overestimate the deformation compared with the measured deformation, however good qualitative correspondence is observed between the predicted and measured values. Secondly, inherent anisotropy is predicted by the modification of shear resistance on potential sliding plane. Thirdly, hardening effect in the direction of preshearing and softening effect in the opposite direction are properly predicted with Masing's rule for the cyclic shear stress-strain relationship on the potential sliding plane which is combined into the model. A program code (MDSM-E) is developed to model the deformation of soil element in laboratory soil element tests. |
| Year | 2000 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-99-14 |
| Type | Thesis |
| School | School of Civil Engineering |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Kinya Miura; |
| Examination Committee(s) | Balasubramaniam, A.S.;Lin, Der Guey;Noppadol Phien-wej; |
| Scholarship Donor(s) | The Government of Japan; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2000 |