As a green environmentally-friendly material,rubberised concrete(Ru C),which has the characteristics of low elastic modulus,large deformation capacity,high damping,good energy dissipation and good crack resistance,has...As a green environmentally-friendly material,rubberised concrete(Ru C),which has the characteristics of low elastic modulus,large deformation capacity,high damping,good energy dissipation and good crack resistance,has attracted extensive attention and research in the civil engineering discipline.However,most of existing studies are based on experimental tests on Ru C material properties,and there has been no numerical study based on meso-scale modelling of Ru C yet.To more comprehensively investigate the Ru C dynamic material properties without conducting intensive experimental tests,this study developed a high-fidelity meso-scale model considering coarse and fine aggregates and rubber crumbs to numerically investigate the mechanical properties of rubberised concrete under different strain rates.The meso-scale model was verified against both quasi-static compressive testing data and Split Hopkinson Pressure Bar(SHPB)dynamic testing data.Using the verified numerical model,the dynamic properties of rubberised concrete with various rubber content(0%-30%)under different strain rates were studied.The numerical results show that the developed meso-scale model can use to predict the static and dynamic properties of rubberised concrete with high accuracy.The dynamic compressive strength of the rubberised concrete increases with the increment of the strain rate,and the strain rate sensitivity increases with the rubber content ranging from 0 to 30%.Based on intensive numerical simulation data,empirical DIFs is used as a function of strain rate and rubber content to predict the dynamic strength of rubberised concrete.展开更多
To investigate the dynamic response problem of the double medium formed by the adherence of sprayed concrete and surrounding rock in the tunnel,a split Hopkinson pressure bar of 75 mm in diameter was adopted at the ag...To investigate the dynamic response problem of the double medium formed by the adherence of sprayed concrete and surrounding rock in the tunnel,a split Hopkinson pressure bar of 75 mm in diameter was adopted at the ages of 3,7 and 10 d.Experimental results showed that dynamic compressive strength and dynamic increase factors(DIF)of the combined bodies increase with the strain rate.With the growth of strain rate,the critical strain of the combined bodies first increases,then deceases.Furthermore,the combined bodies of 3 d reveal the plastic property and brittle property for 7 d and 10 d when the strain rate is over 80/s.The failure characteristic of the sprayed concrete changes from tearing strain damage to crushing damage as the growth of strain rate,and the failure characteristic of rock presents the tensile failure mode as demonstrated by the scanning electron microscope(SEM).展开更多
In this study,to confirm the effect of confining pressure on dynamic mechanical behavior and failure modes of concrete,a split Hopkinson pressure bar dynamic loading device was utilized to perform dynamic compressive ...In this study,to confirm the effect of confining pressure on dynamic mechanical behavior and failure modes of concrete,a split Hopkinson pressure bar dynamic loading device was utilized to perform dynamic compressive experiments under confined and unconfined conditions.The confining pressure was achieved by applying a lateral metal sleeve on the testing specimen which was loaded in the axial direction.The experimental results prove that dynamic peak axial stress,dynamic peak lateral stress,and peak axial strain of concrete are strongly sensitive to the strain rate under confined conditions.Moreover,the failure patterns are significantly affected by the stress-loading rate and confining pressure.Concrete shows stronger strain rate effects under an unconfined condition than that under a confined condition.More cracks are created in concrete subjected to uniaxial dynamic compression at a higher strain rate,which can be explained by a thermal-activated mechanism.By contrast,crack generation is prevented by confinement.Fitting formulas of the dynamic peak stress and dynamic peak axial strain are established by considering strain rate effects(50–250 s-1)as well as the dynamic confining increase factor(DIFc).展开更多
文摘As a green environmentally-friendly material,rubberised concrete(Ru C),which has the characteristics of low elastic modulus,large deformation capacity,high damping,good energy dissipation and good crack resistance,has attracted extensive attention and research in the civil engineering discipline.However,most of existing studies are based on experimental tests on Ru C material properties,and there has been no numerical study based on meso-scale modelling of Ru C yet.To more comprehensively investigate the Ru C dynamic material properties without conducting intensive experimental tests,this study developed a high-fidelity meso-scale model considering coarse and fine aggregates and rubber crumbs to numerically investigate the mechanical properties of rubberised concrete under different strain rates.The meso-scale model was verified against both quasi-static compressive testing data and Split Hopkinson Pressure Bar(SHPB)dynamic testing data.Using the verified numerical model,the dynamic properties of rubberised concrete with various rubber content(0%-30%)under different strain rates were studied.The numerical results show that the developed meso-scale model can use to predict the static and dynamic properties of rubberised concrete with high accuracy.The dynamic compressive strength of the rubberised concrete increases with the increment of the strain rate,and the strain rate sensitivity increases with the rubber content ranging from 0 to 30%.Based on intensive numerical simulation data,empirical DIFs is used as a function of strain rate and rubber content to predict the dynamic strength of rubberised concrete.
基金Supported by the National Key Research Program(2017YFC0804200)the National Key Basic Research Program(2016YFC0600903)the National Natural Science Foundation of China(51274204)
文摘To investigate the dynamic response problem of the double medium formed by the adherence of sprayed concrete and surrounding rock in the tunnel,a split Hopkinson pressure bar of 75 mm in diameter was adopted at the ages of 3,7 and 10 d.Experimental results showed that dynamic compressive strength and dynamic increase factors(DIF)of the combined bodies increase with the strain rate.With the growth of strain rate,the critical strain of the combined bodies first increases,then deceases.Furthermore,the combined bodies of 3 d reveal the plastic property and brittle property for 7 d and 10 d when the strain rate is over 80/s.The failure characteristic of the sprayed concrete changes from tearing strain damage to crushing damage as the growth of strain rate,and the failure characteristic of rock presents the tensile failure mode as demonstrated by the scanning electron microscope(SEM).
基金supported by the National Natural Science Foundation of China(Nos.52027814 and 51839009)。
文摘In this study,to confirm the effect of confining pressure on dynamic mechanical behavior and failure modes of concrete,a split Hopkinson pressure bar dynamic loading device was utilized to perform dynamic compressive experiments under confined and unconfined conditions.The confining pressure was achieved by applying a lateral metal sleeve on the testing specimen which was loaded in the axial direction.The experimental results prove that dynamic peak axial stress,dynamic peak lateral stress,and peak axial strain of concrete are strongly sensitive to the strain rate under confined conditions.Moreover,the failure patterns are significantly affected by the stress-loading rate and confining pressure.Concrete shows stronger strain rate effects under an unconfined condition than that under a confined condition.More cracks are created in concrete subjected to uniaxial dynamic compression at a higher strain rate,which can be explained by a thermal-activated mechanism.By contrast,crack generation is prevented by confinement.Fitting formulas of the dynamic peak stress and dynamic peak axial strain are established by considering strain rate effects(50–250 s-1)as well as the dynamic confining increase factor(DIFc).
