Continuum damage mechanics introduces damage because of two reasons: giving the change of elastic properties of materials under different loading conditions and to get failure criteria when damage reaches a critical value. Critical damage is given as an external condition, independently of the dynamic properties. In a non-equilibrium thermodynamic theoretical frame damage development and failure are connected, failure is treated as a thermodynamic instability in the non-equilibrium part of the state space. In this lecture we give some examples demonstrating the possibilities of the thermodynamic approach. We will see, that to understand some dynamic properties of soil and rock materials makes unavoidable to go beyond the classical rheologycal approaches and consider failure as dynamic instability.
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