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Abstract Based on the scientific understanding of deep rock under high crustal stress and dynamic excavating perturbation，the dynamic failure characteristics of sandstone subjected to three-dimensional(3D) coupled static and dynamic loads are experimentally studied preliminarily with a modified 3D split Hopkinson pressure bar(SHPB) apparatus. Three levels of confining pressures(0，5 and 10 MPa) and three typical levels of axial compressions(60，80 and 100 MPa)，are designed；and the 3D coupled loads tests are carried out under different strain rates. The results show that，when the confining pressure is constant，the impact compressive strength will decrease when the ratio of axial compressive stress to axial compressive ultimate capacity increases from 0.52 to 0.87. Compared with the influence of confining pressure 10 MPa，the impact compressive strength changes a little under confining pressure 5 MPa. The results also show that the axial pressure will induce the internal cracks in rock，weaken the carrying capacity of microelement and reduce the secant modulus of rock；While the confining pressure will inhibit the initiation and propagation of cracks，consolidate the carrying capacity of microelement and enhance the secant modulus of rock. When the confining pressure is constant，the results also show that the release energy per unit volume will decrease when the ratio of axial compressive stress to axial compressive ultimate capacity increases and change into absorbing energy state at the ratio of axial compressive stress to axial compressive ultimate capacity of 0.6–0.7. The rock will show a single-cone compression-shear failure model under 3D coupled static and dynamic loads.
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Received: 14 February 2011
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2011, Vol. 30 
