RESEARCH ON NON-LINEAR RHEOLOGICAL MODEL OF ROCK

摘要

The paper is to research the non-linear rheological model of rock. Firstly, a new concept of potential strength is proposed. Then the creep process is divided into numerous instancys, and in every instancy, the instant potential strength can be represented by the instant summit strength to some degree. The instant summit strength is the function of visco-plastic strength. With the development of visco-plastic strain, the damage in rock develops, and the instant summit strength decreases accordingly. When the instant summit strength decreases to be equal to the applied stress, the creep reaches the critical state to the tertiary creep. With the damage going on developing, the instant summit strength changes to be lower than the applied stress, which results in the tertiary creep. Through the instant summit strength, an instant yield function is established, which represents the instant state of the rock. The fluidity parameter is the function of time, applied load, instant strength and the damage in rock. It can be transferred to be the function of time and the instant yield function. So the non-linear fluidity parameter can be established, which includes the linear and non-linear creep properties in a unified form. Based on the parameter and the Nishihara creep model, a non-linear creep model is established, which can also be seen as the generalization of the Nishihara creep model from linear to non-linear. Finally, by numerical calculation, the model is demonstrated to be effective to imitate all the three stages of creep.