The purpose of this review is to discuss the development and the state of the art in dynamic testing techniques and dynamic mechanical behaviour of rock materials. The review begins by briefly introducing the history of rock dynamics and explaining the significance of studying these issues. Loading techniques commonly used for both intermediate and high strain rate tests and measurement techniques for dynamic stress and deformation are critically assessed in Sects. 2 and 3. In Sect. 4, methods of dynamic testing and estimation to obtain stress–strain curves at high strain rate are summarized, followed by an in-depth description of various dynamic mechanical properties (e.g. uniaxial and triaxial compressive strength, tensile strength, shear strength and fracture toughness) and corresponding fracture behaviour. Some influencing rock structural features (i.e. microstructure, size and shape) and testing conditions (i.e. confining pressure, temperature and water saturation) are considered, ending with some popular semi-empirical rate-dependent equations for the enhancement of dynamic mechanical properties. Section 5 discusses physical mechanisms of strain rate effects. Section 6 describes phenomenological and mechanically based rate-dependent constitutive models established from the knowledge of the stress–strain behaviour and physical mechanisms. Section 7 presents dynamic fracture criteria for quasi-brittle materials. Finally, a brief summary and some aspects of prospective research are presented.

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A Review of Dynamic Experimental Techniques and Mechanical Behaviour of Rock Materials

Local impact effects of hard missiles on concrete targets

Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems. Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsky bar systems, which include both split Hopkinson pressure bar (SHPB) and split Hopkinson tension bar (SHTB) systems. Significant progress has been made on the quantification of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system. This review aims to fully describe and critically assess the detailed procedures and principles of techniques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined, followed by the key loading techniques that are useful for dynamic rock tests with SHPB (i.e. pulse shaping, momentum-trap and multi-axial loading techniques). Various measurement techniques for rock tests in SHPB (i.e. X-ray micro computed tomography (CT), laser gap gauge (LGG), digital image correlation (DIC), Moire method, caustics method, photoelastic coating method, dynamic infrared thermography) are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements (i.e. dynamic compression, tension, bending and shear tests), dynamic fracture measurements (i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity), and dynamic techniques for studying the influences of temperature and pore water.

https://cyberleninka.org/article/n/236168.pdf

Dynamic rock tests using split Hopkinson (Kolsky) bar system – A review

Modelling of compressive behaviour of concrete-like materials at high strain rate

Impact mechanical properties of basalt fiber reinforced geopolymeric concrete (BFRGC), including dynamic compressive strength, deformation and energy absorption capacity, were studied using a 100-mm-diameter split Hopkinson pressure bar (SHPB) system. For the valid SHPB tests on BFRGC specimens, the improved pulse shaping techniques were proposed to obtain dynamic stress equilibrium and nearly constant strain rate loading over most of the test durations. Impact properties of BFRGC exhibit strong strain rate dependency, and increase approximately linearly with the strain rate. The addition of basalt fiber can significantly improve deformation and energy absorption capacities of geopolymeric concrete (GC), while there is no notable improvement in dynamic compressive strength. In addition, the optimum volume fraction of basalt fiber was presented for BFRGC.

H Meng

Papers

About the dynamic strength enhancement of concrete-like materials in a split Hopkinson pressure bar test