Rock failure, wave propagation and tunnel stability under dynamic loads

This keynote paper addresses the dynamic aspects of rock mechanics, specifically the rock failure, shock wave transmission, and behaviour of rock tunnel, subjected to shock loads of explosion and impact. For many years, researches on rock dynamics including rock dynamic testing, rock dynamic modeling, dynamic properties of rock fractures, shock wave propagation in fractured rock, and design of rock tunnels under dynamic loading have been carried out by the authors and their research groups. Rock dynamic test results showed that the strengths of granitic rock samples were strain-rate dependent which requested to develop strain-rate-dependent rock constitutive relations and failure criteria. Rock dynamic failure has also been simulated by using smoothed particle hydrodynamics method and considering heterogeneity effect of rock materials. Wave propagation across single, multiple joints and in rock mass have also been studied by analytical and numerical methods. Some dynamic design specifications for rock tunnels have been reviewed based on large scale underground explosion tests. It has been shown that the current design guideline for rock tunnels against blast loading is rather conservative in determination of rock spalling and safe separation distance.