A semi-micromechanical MULTILAMINATE model is introduced here to predict the mechanical behavior of soils.This model is like a bridge between micro and macro scale upon the satisfaction of minimum potential energy level during any applied stress/strain increments. The concept of this model is based on a certain number of sampling planes which constitute the elastic-plastic behavior of the soil. The soil behavior presents as the summation of behavior on these planes. A simple unconventional constitutive equation is used in each of the planes to describe the behavior of these planes separately. An unconventional plasticity can predict the soil behavior as a smooth curve with considering plastic deformation due to change of stress state inside the yield surface. The model is capable of predicting softening behavior of the soil in a reasonable manner due to using unconventional plasticity. The influences of induced anisotropy are included in a rational way without any additional hypotheses owing to in-nature properties of the MULTILAMINATE framework. Results of this model are compared with test data and reasonable agreement is found.

The present paper is devoted to a new critical state based plasticity model able to predict drained and undrained behaviour of granular material. It incorporates a bounding surface plasticity model describing in MULTILAMINATE framework to capitalize on advantages of this mathematical framework. Most of the models developed using stress/strain invariants are not capable of identifying the parameters depending on directional effects such as principal stress rotation and fabric, this is mainly because stress/strain invariants are scalar quantities. The principal features of this model can be postulated as considering both inherent and induced anisotropy, principal stress rotation. Since the local instability of saturated sand within post-liquefaction is highly dependent on the residual inherent/induced anisotropy, bedding plane effects and also the stress/strain path the new mode is competent to be employed in this regard. The constitutive equations of the model are derived within the context of non-linear elastic behaviour for the whole medium and plastic sliding of interfaces of predefined planes. As follows, the constitutive equations are described in detail and then the experimental results and sensitive analysis of key material constants are shown which all imply the power of the model in predicting of soil behaviour under any condition in soil structures.

A framework for development of constitutive models based on semi-micromechanical aspects of plasticity is proposed. The resulting of this model for material employed friction type failure criterion, sub-loading surface, and associated flow rule. This model is capable of predicting effects of the rotation of principal stress/strain axes and consequent plastic flow, induced anisotropy of strength, particularly, in cyclic loading. Also, this model has the potential of predicting the behavior of fully inherent anisotropic material, and strain history distributions at a point up to failure. The predicted model results and their conformity with experimental results of cyclic loading including the pre-failure specifications show the capability of the mode.

This paper presents a macro model to predict unreinforced masonry structures in plane behavior. The model is based on the concept of MULTILAMINATE theory. In the past, the method has been used to model behavior of soil, disregarding the cohesion and the tensile strength. Regarding its mathematical base, and the possibility of applying in other cases, this method is used to predict the ultimate failur load in URM structures in present study. This model is intrinsically capable of spotting induced anisotropy of brittle material such as concrete, rocks and masonry, develponig as a result of cracking. Here, the yield surface applied, consists an generalized mohr-coulomb yield surface, along with a cap model and a cut-off tensile. Comparing numerical results predicted to be obtained in non-linear analysis of masonry structures unreinforced against lateral load, with the results of ther experimental data shows capability of the model in failure analysis of URM structures.

In this study, two behavioral models—unified and MULTILAMINATE—are employed to simulate soil behavior. The unified model incorporates a non-associated flow rule along with the critical state concept. Additionally, the sub-loading surface concept is adopted to capture a smooth elastic-plastic transition. For numerical implementation, the implicit Euler method is used. The MULTILAMINATE model is based on a 13-plane framework, in which each plane exhibits elastic-plastic behavior. The overall soil response is obtained by integrating the elastic-plastic responses of the individual planes oriented in various directions at a material point. A set of unconventional constitutive equations is applied to each plane. This model captures soil softening behavior more realistically due to the use of a non-classical plasticity approach. Moreover, it accounts for the effect of induced anisotropy. To evaluate the models, four clay samples subjected to monotonic loading—under both drained and undrained conditions—were analyzed using both the unified and MULTILAMINATE models and were compared with experimental data. The results demonstrate that the unified model offers a more favorable representation of soil behavior.

This paper proposes a framework for the constitutive model based on the semi-micromechanical aspects of plasticity, including damage progress for simulating behavior of concrete under multiaxial loading. This model is aimed to be used in plastic and fracture analysis of both regular and reinforced concrete structures, for the framework of sample plane crack approach. This model uses MULTILAMINATEd framework with sub-loading surface to provide isotropic and kinematics hardening/softening in the ascending/descending branches of loading. In MULTILAMINATEd framework a relation between stress/strain and yield function on planes of various orientation is defined and stress/strain path history for each plane is kept for a sequence of future analysis. Four basic stress states including compression-shear with increase/decrease in the compression/shear ratio,tension-shear and pure compression are defined and the constitutive law for each plane is derived from the most influenced combination of stress states. With using sub-loading aspect of the surface, the kinematics and isotropic hardening are applied to the model to make it capable of simulating the behavior under any stress path, such as cyclic loading in the ascending/descending branch of loading. Based on the experimental results of the literature, the model parameters are calibrated. The model results under monotonic loading and also different states of cyclic loadings such as uniaxial compression, tension, alternate compression tension, shear and triaxial compression are compared with experimental results that shows the capability of the model.

Rock abutments of arch dam consist of jointed rock mass whose strength is based on strike, dip, spacing and behavior of rock joints. Behavior of rock joints depends on spacing, friction, wall strength of joint, joint filling amount and water pressure. Abutments are the most important and sensitive parts of arch dam sites. In fact the stability of dam depends directly on the stability of it:" abutments. Therefore in this research jointed rock mass of abutment is modeled by using a MULTILAMINATE model. The stability of abutment is studied in diffrent cases of bedding and joint sets. The constitutive model for joint sets is a nonlinear viscoplastic lnaterial. The MULTILAMINATE model is based on an equivalent material approach and is obtained hy integrating of mechanical response of intact rock and joints. It is capable of modeling sliding/opening/ closing of multiple joint sets in the rock mass and any yield function of joint can be incorporated in it. Here we take use of this model for predicting the sliding in abutments of dam under hydrostatic force, rock weight and uplift loads using Bartons criterion.

In this paper, a unified behavioral model is used to simulate the behavior of anisotropic rocks. The proposed unified behavioral model employs the non-associated flow rule and the concept of critical state. Furthermore, the proposed model is developed based on the concept of the sub-loading surface to predict the smooth transition behavior from elastic to plastic states. To implement the model, the implicit Euler method is utilized. For modeling anisotropy, a 13-plane model is employed, with each of these planes exhibiting elastoplastic behavior. The overall behavior of the soil is calculated by assessing the separate behavior of multiple individual planes in different directions at a point. A set of unconventional constitutive equations is used separately for each plane. Using this model, the induced anisotropic effects are simulated. Subsequently, three rock samples under monotonic loading in drained conditions are simulated with the unified behavioral model and compared with laboratory data. For each of the tests conducted at different confining pressures, the deviatoric stress-axial strain and volumetric strain-axial strain graphs were plotted. Based on the results obtained from the numerical simulations, the strain softening behavior, maximum stress, and the behavior of rock samples before and after maximum stress. It was shown that the developed model can be effectively used to simulate the behavior of rocks.

Existence of discontinuities causes higher deformability and lower strength in rock masses. Thus joints can change the rock mass behaviour due to the applied loads. For this reason properties and orientation of the joint sets have a great effect on the stability of rock slopes. In this paper, after introducing some numerical methods for evaluating the factor of safety for the stability of slopes, stability of jointed rock slopes in the plane strain condition is investigated with the strength reduction technique; this method is modified and applied in the MULTILAMINATE framework. First of all, stability of one homogeneous rock slope is investigated and compared with the limit equilibrium method. Then stability of a layered rock slope is analyzed with some modifications in the strength reduction technique. Effects of orientation, tensile strength and dilation of layered joint sets on the factor of safety and location of the sliding block are explained.

Abutments and foundation are among the most vulnerable parts of arch dams therefore, understanding their defects are of high priority. As far as seepage forces have a great effect on abutment stability, understanding the seepage in rock masses has a great importance. Joints hydromechanical interaction is a phenomenon that is not studied sufficiently. In this research, an effective algorithm is devised so that the mechanical behavior of jointed rock mass has been described and modeled by an equivalent continuum rock model with MULTILAMINATE concept and the hydraulic behavior assuming laminar flow with cubic law for joint systems. The hydromechanical interaction is thus modeled for a hypothetical arch dam and the effect of the phenomenon is studied on the stresses, their redistribution and in the rock mass abutments. It is concluded that disregarding the seepage effect or the H-M interaction may introduce significant errors in displacements and shear stresses of dam abutments.