A debris flow forecast model based on a water-soil coupling mechanism that takes the debrisflow watershed as a basic forecast unit was established here for the prediction of disasters at the watershed scale.This was a...A debris flow forecast model based on a water-soil coupling mechanism that takes the debrisflow watershed as a basic forecast unit was established here for the prediction of disasters at the watershed scale.This was achieved through advances in our understanding of the formation mechanism of debris flow.To expand the applicable spatial scale of this forecasting model,a method of identifying potential debris flow watersheds was used to locate areas vulnerable to debris flow within a forecast region.Using these watersheds as forecasting units and a prediction method based on the water-soil coupling mechanism,a new forecasting method of debris flow at the regional scale was established.In order to test the prediction ability of this new forecasting method,the Sichuan province,China was selected as a study zone and the large-scale debris flow disasters attributable to heavy rainfall in this region on July 9,2013 were taken as the study case.According to debris flow disaster data on July 9,2013 which were provided by the geo-environmental monitoring station of Sichuan province,there were 252 watersheds in which debris flow events actually occurred.The current model predicted that 265 watersheds were likely to experience a debris flow event.Among these,43 towns including 204 debrisflow watersheds were successfully forecasted and 24 towns including 48 watersheds failed.The false prediction rate and failure prediction rate of thisforecast model were 23% and 19%,respectively.The results show that this method is more accurate and more applicable than traditional methods.展开更多
Three test models and a simulation model were constructed based on the prevailing conditions of the Taiping coalmine in order to analyze pore pressure fluctuations of an overlying aquifer during residual coal mining. ...Three test models and a simulation model were constructed based on the prevailing conditions of the Taiping coalmine in order to analyze pore pressure fluctuations of an overlying aquifer during residual coal mining. As well, the relation between pore pressure and soil stress was evaluated. The model tests show the vibrations of pore pressure and soil stress as a result of mining activities. The simulation model tells of the response characteristics of pore pressure after mining and its distribution in the sand aquifer. The comparative analysis reveals that pore pressure and soil stress vibration are activated by unexpected events occurring in mines, such as collapsing roofs. An increased pore pressure zone always lies above the wall in front or behind the working face of a mine. Both pore pressure and vertical stress result in increasing and decreasing processes during movements of the working face of a mine. The vibration of pore pressure always precedes soil stress in the same area and ends with a sharp decline. Changes in pore pressure of sand aquifer are limited to the area of stress changes. Obvious changes are largely located in a very small frame over the mining face.展开更多
In the present work,an incompressible smoothed particle hydrodynamic(SPH)method is introduced to simulate water-soil-structure interactions.In the current calculation,the water is modelled as a Newtonian fluid.The soi...In the present work,an incompressible smoothed particle hydrodynamic(SPH)method is introduced to simulate water-soil-structure interactions.In the current calculation,the water is modelled as a Newtonian fluid.The soil is modelled in two different cases.In the first case,the granular material is considered as a fluid where a Bingham type constitutive model is proposed based on Mohr-Coulomb yield-stress criterion,and the viscosity is derived from the cohesion and friction angle.In addition,the fictitious suspension layers between water and soil depending on the concentration of soil are introduced.In the second case,Hooke’s law introduces elastic soil.In ISPH,the pressure is evaluated by solving the pressure Poisson equation using a semi-implicit algorithm based on the projection method and an eddy viscosity for water is modelled by a large eddy simulation with the Smagorinsky model.In the proposed ISPH method,the pressure is stabilized to simulate the multiphase flow between soil and water.Numerical experiments for water-soil suspension flow of Louvain erosional dam break with flat soil foundation,is simulated and validated using 3D-ISPH method.Coupling between water-soil interactions with different solid structures are simulated.The results revealed that,the suspension layers with the Bingham model of soil gives more accurate results in the experiment as compared to the case of the Bingham model without suspension layers.In addition,the elastic soil model by the Hooke’s law can simulate soil hump accurately as compared to the Bingham model.From the simulations,avoiding erosion behind the structure for preventing the structure break during flood are investigated by using an extended structure or a wedge structure.展开更多
基金supported by the foundation of the Research Fund for Commonweal Trades (Meteorology) (Grant No. GYHY201006039)the International Cooperation Project of the Department of Science and Technology of Sichuan Province (Grant No. 2009HH0005)
文摘A debris flow forecast model based on a water-soil coupling mechanism that takes the debrisflow watershed as a basic forecast unit was established here for the prediction of disasters at the watershed scale.This was achieved through advances in our understanding of the formation mechanism of debris flow.To expand the applicable spatial scale of this forecasting model,a method of identifying potential debris flow watersheds was used to locate areas vulnerable to debris flow within a forecast region.Using these watersheds as forecasting units and a prediction method based on the water-soil coupling mechanism,a new forecasting method of debris flow at the regional scale was established.In order to test the prediction ability of this new forecasting method,the Sichuan province,China was selected as a study zone and the large-scale debris flow disasters attributable to heavy rainfall in this region on July 9,2013 were taken as the study case.According to debris flow disaster data on July 9,2013 which were provided by the geo-environmental monitoring station of Sichuan province,there were 252 watersheds in which debris flow events actually occurred.The current model predicted that 265 watersheds were likely to experience a debris flow event.Among these,43 towns including 204 debrisflow watersheds were successfully forecasted and 24 towns including 48 watersheds failed.The false prediction rate and failure prediction rate of thisforecast model were 23% and 19%,respectively.The results show that this method is more accurate and more applicable than traditional methods.
基金Project supported by Qing Lan Project of Jiangsu, China
文摘Three test models and a simulation model were constructed based on the prevailing conditions of the Taiping coalmine in order to analyze pore pressure fluctuations of an overlying aquifer during residual coal mining. As well, the relation between pore pressure and soil stress was evaluated. The model tests show the vibrations of pore pressure and soil stress as a result of mining activities. The simulation model tells of the response characteristics of pore pressure after mining and its distribution in the sand aquifer. The comparative analysis reveals that pore pressure and soil stress vibration are activated by unexpected events occurring in mines, such as collapsing roofs. An increased pore pressure zone always lies above the wall in front or behind the working face of a mine. Both pore pressure and vertical stress result in increasing and decreasing processes during movements of the working face of a mine. The vibration of pore pressure always precedes soil stress in the same area and ends with a sharp decline. Changes in pore pressure of sand aquifer are limited to the area of stress changes. Obvious changes are largely located in a very small frame over the mining face.
基金This work was supported by Deanship of Scientific Research at King Khalid University,Abha,Saudi Arabia,through the Research Group Project under grant number R.G.P2/70/41.
文摘In the present work,an incompressible smoothed particle hydrodynamic(SPH)method is introduced to simulate water-soil-structure interactions.In the current calculation,the water is modelled as a Newtonian fluid.The soil is modelled in two different cases.In the first case,the granular material is considered as a fluid where a Bingham type constitutive model is proposed based on Mohr-Coulomb yield-stress criterion,and the viscosity is derived from the cohesion and friction angle.In addition,the fictitious suspension layers between water and soil depending on the concentration of soil are introduced.In the second case,Hooke’s law introduces elastic soil.In ISPH,the pressure is evaluated by solving the pressure Poisson equation using a semi-implicit algorithm based on the projection method and an eddy viscosity for water is modelled by a large eddy simulation with the Smagorinsky model.In the proposed ISPH method,the pressure is stabilized to simulate the multiphase flow between soil and water.Numerical experiments for water-soil suspension flow of Louvain erosional dam break with flat soil foundation,is simulated and validated using 3D-ISPH method.Coupling between water-soil interactions with different solid structures are simulated.The results revealed that,the suspension layers with the Bingham model of soil gives more accurate results in the experiment as compared to the case of the Bingham model without suspension layers.In addition,the elastic soil model by the Hooke’s law can simulate soil hump accurately as compared to the Bingham model.From the simulations,avoiding erosion behind the structure for preventing the structure break during flood are investigated by using an extended structure or a wedge structure.
