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.
Studies of rock dynamics have been performed by the research groups led by the authors at the Nanyang Technological University (NTU) of Singapore since middle 1990s, and later also at the Ecole Polytechnique Federale de Lausanne (EPFL) of Switzerland. This keynote paper presents a brief introduction and update of the recent understanding of rock dynamics from rock dynamic testing to rock dynamic modeling, wave propagation through fractured rock and rock mass, and tunnel safety and support design under dynamic loading. Rock dynamics is of particular interests in civil and mining engineering, and protective technology. Rock material has some special features, such as being brittle, heterogeneous, porous, pressure- and rate-sensitive on deformation and strengths, swelling and weathering effect due to interaction with water and air, etc., which make the rock mechanical properties highly scattered and unpredictable. In dynamic conditions, those heterogeneities, porosities, inherent micro-cracks and water effect in rock materials may play more important role in fracture initiation, propagation and coalesce than in static conditions. Although rock mechanics and rock testing methods have been rapidly developed in the past a few decades, the mechanisms of rock dynamic failure and strainrate effect are still far from fully understood, especially when the above mentioned factors are under concern. On the other hand, rock mass are always jointed with different kind of discontinuities with different sizes and geometries, which dominant the stress wave propagation and attenuation in rock mass. Traditional continuums mechanics based on equivalent media developed in quasi-static loading conditions may not be applicable in stress/shock wave propagations in such jointed rock mass, where contact surfaces govern the wa Besides, tunnel design against dynamic/shock loading is based on very rough design criteria 168 due to lack of understanding of rock mass failure under dynamic loading conditions as well as highly variable and complex nature of geology.