The rheological properties of most liquid in nature are between liquids and solids, including both elastic changes and viscosity changes, that is socalled ＂viscoelastic＂. Dynamic oscillatory test was used to quantit...The rheological properties of most liquid in nature are between liquids and solids, including both elastic changes and viscosity changes, that is socalled ＂viscoelastic＂. Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study. The debris flow slurry samples were from Jiangjiagou Ravine, Yunnan Province, China. The experimental results were found that at the low and middle stages of shearing, when the angular velocity 09〈72.46 s-1, the loss modulus （G was greater than the storage modulus （G3, i.e. G＂〉G＇. At the late stage of shearing, when the angular velocity co-72.46 s-x, the storage modulus was greater than or equal to the loss G = G, tan -〈 1 （where phase-shift modulus, i.e. ＇ 〉 ＂ angle 5=G＂,/G3, and the debris flow slurry was in a gel state. Therefore, the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines.展开更多
The problem of scattering of SH-wave by a circular cavity and an arbitrary beeline crack in right-angle plane was investigated using the methods of Green's function,complex variables and muti-polar coordinates.Fir...The problem of scattering of SH-wave by a circular cavity and an arbitrary beeline crack in right-angle plane was investigated using the methods of Green's function,complex variables and muti-polar coordinates.Firstly,we constructed a suitable Green's function,which is an essential solution to the displacement field for the elastic right-angle plane possessing a circular cavity while bearing out-of-plane harmonic line source load at arbitrary point.Secondly,based on the method of crack-division,integration for solution was established,then expressions of displacement and stress were obtained while crack and circular cavities were both in existence.Finally,the dynamic stress concentration factor around the circular cavity and the dynamic stress intensity factor at crack tip were discussed to the cases of different parameters in numerical examples.Calculation results show that the crack produces adverse engineering influence on both of the dynamic stress concentration factor and the dynamic stress intensity factor.展开更多
This article analyzed climate change risks from the perspective of con- temporary environmental risks and how they have been internalized by policy. In order to do so, the main characteristics of this type of risk wer...This article analyzed climate change risks from the perspective of con- temporary environmental risks and how they have been internalized by policy. In order to do so, the main characteristics of this type of risk were analyzed based on the contributions from social theory authors on contemporary environmental risks. Next, the implications of these characteristics for the production of policy responses to climate change risks were discussed. The two main types of policy responses to climate change in the literature were presented： mitigation and adaptation. Finally, their interaction, differences and possibilities for synergy were analyzed. Under- standing climate change as a contemporary environmental risk, the way it was presented in this article, implies a radical change in the development bases of society, since greenhouse gases emissions from human activities contribute to the aggravation of global warming. Climate change challenges the traditional ways of governing in many ways, since climate change policy should involve the ques- tioning of the current processes of development. Profound changes in ways of thinking and established political action are needed.展开更多
基金supported by the Youth Talent Team Program of Institute of Mountain Hazards and Environment,CASthe National Natural Science Foundation of China (Grant No.406710260)
文摘The rheological properties of most liquid in nature are between liquids and solids, including both elastic changes and viscosity changes, that is socalled ＂viscoelastic＂. Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study. The debris flow slurry samples were from Jiangjiagou Ravine, Yunnan Province, China. The experimental results were found that at the low and middle stages of shearing, when the angular velocity 09〈72.46 s-1, the loss modulus （G was greater than the storage modulus （G3, i.e. G＂〉G＇. At the late stage of shearing, when the angular velocity co-72.46 s-x, the storage modulus was greater than or equal to the loss G = G, tan -〈 1 （where phase-shift modulus, i.e. ＇ 〉 ＂ angle 5=G＂,/G3, and the debris flow slurry was in a gel state. Therefore, the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines.
文摘The problem of scattering of SH-wave by a circular cavity and an arbitrary beeline crack in right-angle plane was investigated using the methods of Green's function,complex variables and muti-polar coordinates.Firstly,we constructed a suitable Green's function,which is an essential solution to the displacement field for the elastic right-angle plane possessing a circular cavity while bearing out-of-plane harmonic line source load at arbitrary point.Secondly,based on the method of crack-division,integration for solution was established,then expressions of displacement and stress were obtained while crack and circular cavities were both in existence.Finally,the dynamic stress concentration factor around the circular cavity and the dynamic stress intensity factor at crack tip were discussed to the cases of different parameters in numerical examples.Calculation results show that the crack produces adverse engineering influence on both of the dynamic stress concentration factor and the dynamic stress intensity factor.
文摘This article analyzed climate change risks from the perspective of con- temporary environmental risks and how they have been internalized by policy. In order to do so, the main characteristics of this type of risk were analyzed based on the contributions from social theory authors on contemporary environmental risks. Next, the implications of these characteristics for the production of policy responses to climate change risks were discussed. The two main types of policy responses to climate change in the literature were presented： mitigation and adaptation. Finally, their interaction, differences and possibilities for synergy were analyzed. Under- standing climate change as a contemporary environmental risk, the way it was presented in this article, implies a radical change in the development bases of society, since greenhouse gases emissions from human activities contribute to the aggravation of global warming. Climate change challenges the traditional ways of governing in many ways, since climate change policy should involve the ques- tioning of the current processes of development. Profound changes in ways of thinking and established political action are needed.
