The permeability evolution of rock during the progressive failure process is described. In combination with the strength degradation index, the degradation formulas of s and a, which are dependent on the plastic confi...The permeability evolution of rock during the progressive failure process is described. In combination with the strength degradation index, the degradation formulas of s and a, which are dependent on the plastic confining strain component, the material constants of Hock-Brown failure criterion are presented, and a modified elemental scale elastic-brittle-plastic constitutive model of rock is established. The rela- tionship between volumetric strain and permeability through tri-axial compression is investigated. Based on the above, a permeability evolution model is established. The model incorporates confining pressure- dependent degradation of strength, dilatancy and corresponding permeability evolution. The model is implemented in FLAC by the FISH function method. The permeability evolution behavior of rock is inves-tigated during the progressive failure process in a numerical case. The results show that the model is cap- able of reproducing, and allowing visualization of a range of hydro-mechanical responses of rock. The effects of confining pressure on degradation of strength, dilatancy and permeability evolution are also reflected.展开更多
An Giang province in the Mekong Delta is the most vulnerable province the impact of flooding and climate variability. Thousand of households are at risk due to severe annual floods. This study applied the LVI （liveli...An Giang province in the Mekong Delta is the most vulnerable province the impact of flooding and climate variability. Thousand of households are at risk due to severe annual floods. This study applied the LVI （livelihood vulnerability index） to estimate flood vulnerability of Phu Huu and Ta Danh villages in An Giang province. Data on socio-demographics, livelihoods, health, social networks, physical, financial and natural resources, natural disasters and climate variability were collected from a survey of 120 households in each village. From these data the LVI of each village was calculated. Results show that the overall LV1 of Phu Huu village, located in the early flooded zone, is higher than that of Ta Danh village, located in the late flooded zone. The analysis also indicated that this practical method can be applied for other purposes such as to monitor vulnerability, evaluate development programs or policy effectiveness by incorporating with scenario comparison.展开更多
The urban vulnerability poses a serious challenge to achieving sustainable devel- opment. With the concentration of the population and the economy, cities must manage the higher frequencies and risks of various hazard...The urban vulnerability poses a serious challenge to achieving sustainable devel- opment. With the concentration of the population and the economy, cities must manage the higher frequencies and risks of various hazards and are becoming more vulnerable. Re- search on the assessment and regulatory control of urban vulnerability is of great significance for both urbanization quality improvement and sustainable development in China or other countries in the world. Because of the complexity of cities and vulnerability concepts, existing studies have focused on different aspects of urban vulnerability. And the research content of urban vulnerability is scattered and relatively independent, leading to a lack of comparability among the research data and resulting in tremendous difficulties in summarizing the conclu- sions through comparison of independent research data. Therefore the goal of this study was to construct urban vulnerability index （UV/） from the perspective of sustainable development that could assess urban vulnerability comprehensively. In this study, we selected 10 subin- dexes involving 36 specific parameters from four aspects （resources, eco-environmental sys- tems, economics, and social development） to construct a comprehensive index system. We also established the standard values of measurements. Then we take 288 prefecture-level cities in China as a study area and evaluate its overall urban vulnerability and its spatial differentiation. Results indicate that urban vulnerability of China has a remarkable spatial differentiation of both ＂gradient distribution＂ and ＂clustered distribution＂; the extent of urban vulnerability corresponds to city size, the bigger the city, the lower its vulnerability; re- source-based cities are more vulnerable than comprehensive cities; a city＇s economic growth rate does not reflect the extent of its urban vulnerability. Further, we offer a few suggestions to cope with urban vulnerability in China.展开更多
基金the National Natural Science Foundation of China (Nos.51274079,51274110 and 51574139)the Natural Science Foundation of Hebei Province (No.E2013208148)
文摘The permeability evolution of rock during the progressive failure process is described. In combination with the strength degradation index, the degradation formulas of s and a, which are dependent on the plastic confining strain component, the material constants of Hock-Brown failure criterion are presented, and a modified elemental scale elastic-brittle-plastic constitutive model of rock is established. The rela- tionship between volumetric strain and permeability through tri-axial compression is investigated. Based on the above, a permeability evolution model is established. The model incorporates confining pressure- dependent degradation of strength, dilatancy and corresponding permeability evolution. The model is implemented in FLAC by the FISH function method. The permeability evolution behavior of rock is inves-tigated during the progressive failure process in a numerical case. The results show that the model is cap- able of reproducing, and allowing visualization of a range of hydro-mechanical responses of rock. The effects of confining pressure on degradation of strength, dilatancy and permeability evolution are also reflected.
文摘An Giang province in the Mekong Delta is the most vulnerable province the impact of flooding and climate variability. Thousand of households are at risk due to severe annual floods. This study applied the LVI （livelihood vulnerability index） to estimate flood vulnerability of Phu Huu and Ta Danh villages in An Giang province. Data on socio-demographics, livelihoods, health, social networks, physical, financial and natural resources, natural disasters and climate variability were collected from a survey of 120 households in each village. From these data the LVI of each village was calculated. Results show that the overall LV1 of Phu Huu village, located in the early flooded zone, is higher than that of Ta Danh village, located in the late flooded zone. The analysis also indicated that this practical method can be applied for other purposes such as to monitor vulnerability, evaluate development programs or policy effectiveness by incorporating with scenario comparison.
基金National Natural Science Foundation of ChinaNo.41371177
文摘The urban vulnerability poses a serious challenge to achieving sustainable devel- opment. With the concentration of the population and the economy, cities must manage the higher frequencies and risks of various hazards and are becoming more vulnerable. Re- search on the assessment and regulatory control of urban vulnerability is of great significance for both urbanization quality improvement and sustainable development in China or other countries in the world. Because of the complexity of cities and vulnerability concepts, existing studies have focused on different aspects of urban vulnerability. And the research content of urban vulnerability is scattered and relatively independent, leading to a lack of comparability among the research data and resulting in tremendous difficulties in summarizing the conclu- sions through comparison of independent research data. Therefore the goal of this study was to construct urban vulnerability index （UV/） from the perspective of sustainable development that could assess urban vulnerability comprehensively. In this study, we selected 10 subin- dexes involving 36 specific parameters from four aspects （resources, eco-environmental sys- tems, economics, and social development） to construct a comprehensive index system. We also established the standard values of measurements. Then we take 288 prefecture-level cities in China as a study area and evaluate its overall urban vulnerability and its spatial differentiation. Results indicate that urban vulnerability of China has a remarkable spatial differentiation of both ＂gradient distribution＂ and ＂clustered distribution＂; the extent of urban vulnerability corresponds to city size, the bigger the city, the lower its vulnerability; re- source-based cities are more vulnerable than comprehensive cities; a city＇s economic growth rate does not reflect the extent of its urban vulnerability. Further, we offer a few suggestions to cope with urban vulnerability in China.
