Abstract
This paper carries out probabilistic analysis of dynamic responses of rock mass under blast loads. Statistical analysis of the initial damage and strength constants of the rock mass is performed by using both the field and laboratory test data. The initial damage of the rock mass is found having the beta distribution, while the critical tensile strain has the normal distribution. These statistical properties are incorporated into the constitutive law and cumulative damage model for rock mass. The statistical estimation of stress wave propagation in the rock mass due to underground explosion is evaluated by Rosenblueth's point estimate method. In numerical calculation, an isotropic continuum damage model considering both the initial damage and the cumulative damage dependent on an equivalent tensile strain is suggested to model rock mass behaviour under blast loads. The suggested models are programmed and linked to an available computer program Autodyn2D through its user's subroutine capability. Using Autodyn2D and the suggested models, stress wave propagation in rock mass with random initial damage induced by underground explosions is simulated. Numerical results of damaged area, peak particle velocity and acceleration attenuation as well as acceleration time histories in the rock mass are compared with those from independent field tests. The effects of statistical variations of initial damage and critical tensile strain of the rock mass on its dynamic responses are also discussed.
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