Modeling Static Behavior of Rockfill Materials Based on Generalized Plasticity Model

Shihai Bian,Bo Wu,Yongzheng Ma

doi:10.1155/2019/2371709

Shihai Bian, Bo Wu + Show 1 more

Open Access

https://doi.org/10.1155/2019/2371709

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Abstract

Rockfill materials are commonly used for dam construction. Establishing an effective model that can reasonably describe the mechanical properties of rockfill material is very important for the calculation of earth-rock dam engineering. Based on the generalized plasticity model of sand, a modified generalized plasticity model suitable for rockfill material is established by modifying the plastic modulus. Focusing on three types of stress paths (e.g., CT test, CP test, and CR test), the stress path adaptability of the modified generalized plasticity is studied. Simulation results show that the proposed model can well predict the strength characteristics while it underestimates the shrinkage characteristics of rockfill materials for constant P test. It is difficult for the generalized plasticity model to predict larger radial shrinkage strain for constant stress ratio tests. This shortcoming can be improved by employing a modified dilatancy equation. Finally, by introducing critical state theory and considering the effect of initial void ratio on plastic modulus, a state-dependent generalized plasticity model is proposed and verified by experiment of granite rockfill materials and TRM with different void ratios. These works covers the most common stress paths related to the construction of earth-rock dams and can capture static behavior of rockfill materials.

Highlights

Earth-rock dams are widely built in the world for their good adaptability to foundation conditions, full use of building excavation materials, and low cost
[10] and the unified generalized plasticity model of sandy soil proposed by Ling and Yang [11] to predict the triaxial loading test and verifies the adaptability of the generalized plasticity model of sandy for the rockfill triaxial test under high confining pressure. e test data are derived from the triaxial experiment of Rumei rockfill under 3200 kPa confining pressure
E proposed model is extended to capture the statedependent behaviors of rockfill materials. ese works allow the following conclusions to be drawn: (1) In the framework of generalized plasticity model, the modified coefficient and the plastic modulus are introduced to modify the generalized plasticity model

Summary

Introduction

Earth-rock dams are widely built in the world for their good adaptability to foundation conditions, full use of building excavation materials, and low cost. E constitutive relationship of rockfill materials becomes a key problem in the calculation and analysis of earth-rock dam. Goorani and Hamidi [6] developed a generalized plasticity model to predict the mechanical behavior of sand-gravel mixtures. Liu and Gao [7] proposed a generalized plasticity model for coarse-grained materials by considering the effect of particle breakage on their critical state behavior. For earth-rock dam engineering, it is necessary to develop a simple and effective model which can capture key characteristic of rockfill materials. Such a model will improve numerical calculation level of earth-rock dam engineering and of great significance to understand mechanical properties of rockfill materials. By comparing the results of conventional triaxial tests and predictions, the rationality of the model is verified. e adaptability of the model under complex stress paths is further studied and extended to state-dependent situations

Modified Generalized Plasticity Model

Validation and Comparison of Other Stress Path

State-Dependent Extension of the Model

Conclusion