Using the self-developed visualization test apparatus, centrifuge model tests at 20 g were carried out to research the macro and microscopic formation mechanism of coarse sand debris flows. The formation mode and soil...Using the self-developed visualization test apparatus, centrifuge model tests at 20 g were carried out to research the macro and microscopic formation mechanism of coarse sand debris flows. The formation mode and soil-water interaction mechanism of the debris flows were analyzed from both macroscopic and microscopic points of view respectively using high digital imaging equipment and micro-structure analysis software Geodip. The test results indicate that the forming process of debris flow mainly consists of three stages, namely the infiltration and softening stage, the overall slide stage, and debris flow stage. The essence of simulated coarse sand slope forming debris flow is that local fluidization cause slope to wholly slide. The movement of small particles forms a transient stagnant layer with increasing saturation, causing soil shear strength lost and local fluidization. When the driving force of the saturated soil exceeds the resisting force, debris flow happens on the coarse sand slope immediately.展开更多
On the basis of the observational data on the annual sediment transport by debris flow in recent 8 years, appling the catastrophe forecast method of Grey System Theory, this study has established the catastrophe model...On the basis of the observational data on the annual sediment transport by debris flow in recent 8 years, appling the catastrophe forecast method of Grey System Theory, this study has established the catastrophe model of the annual sediment transport by debris flow in Jiangjia Gully. It has forecasted the next potential catastrophic year in which the annual sediment transport will be over the catastrophic. threshold 2 million m3. Furthermore, it has introduced the 'equal dimension-new information model', which makes the forecast be done continuously.展开更多
This study proposes a comprehensive method,which consists of field investigation,flume test and numerical simulation,to predict the velocity and sediment thickness of debris flow.The velocity and sediment thickness of...This study proposes a comprehensive method,which consists of field investigation,flume test and numerical simulation,to predict the velocity and sediment thickness of debris flow.The velocity and sediment thickness of the debris flow in mountainous areas can provide critical data to evaluate the geohazard,which will in turn help to understand the debris runout.The flume test of this debris prototype can provide friction coefficient and viscosity coefficient which are important for numerical simulation of debris flow.The relation between the key parameters in the numerical modelling using the Voellmy model and debris-flow rheology is discussed.Through simulation of a debris flow that occurred in Luzhuang gully,it is observed that the debris flow runout determined by the Voellmy model was well consistent with that obtained from field investigation and flume test,demonstrating the effectiveness of this study.The relationship between the Voellmy model and debris flow runout is also proposed.展开更多
To accurately predict impact loads can ensure the safe operation of debris flow control projects.The instantaneous impact process is usually considered in the calculation of the debris flow impact force;however,the re...To accurately predict impact loads can ensure the safe operation of debris flow control projects.The instantaneous impact process is usually considered in the calculation of the debris flow impact force;however,the redistribution of an impact load after structural regulation is unclear.In this study we deduced the theoretical calculation of a debris flow impact on a double-row slit dam,and carried out a verification experiment on the debris flow impact.The calculation model considers the influence of the debris flow properties,dam arrangement and pile material.The results show that the impact force of the debris flow is obviously affected by the bulk density.When the bulk density is 21 kg/m^(3),the maximum impact force on the pile dam is 1.15 times that when the bulk density is 15 kg/m^(3),but the time it takes for the debris flow to pass through the dam body is reduced by 60%.The larger the relative pile spacing,the more sufficient the flow space and the lower the maximum impact force.The maximum impact force of relative pile spacing of 0.8 is 12%less than that of elative pile spacing of 0.5.The horizontal distribution of the impact force in the mud depth range is parabolic.The maximum impact force on the centre pier is 1.3 times that of a side pier,and the maximum impact force on the dam body appears at the top of the mud depth range.From the vertical distribution of the impact force,the maximum impact force at the highest mud mark is approximately 70%of that of the bottom.With the increase in the relative pile spacing,the longitudinal maximum impact force distribution first decreases and then increases.展开更多
基金Funded by National Natural Science Foundation of China(Grant No.41272296)
文摘Using the self-developed visualization test apparatus, centrifuge model tests at 20 g were carried out to research the macro and microscopic formation mechanism of coarse sand debris flows. The formation mode and soil-water interaction mechanism of the debris flows were analyzed from both macroscopic and microscopic points of view respectively using high digital imaging equipment and micro-structure analysis software Geodip. The test results indicate that the forming process of debris flow mainly consists of three stages, namely the infiltration and softening stage, the overall slide stage, and debris flow stage. The essence of simulated coarse sand slope forming debris flow is that local fluidization cause slope to wholly slide. The movement of small particles forms a transient stagnant layer with increasing saturation, causing soil shear strength lost and local fluidization. When the driving force of the saturated soil exceeds the resisting force, debris flow happens on the coarse sand slope immediately.
文摘On the basis of the observational data on the annual sediment transport by debris flow in recent 8 years, appling the catastrophe forecast method of Grey System Theory, this study has established the catastrophe model of the annual sediment transport by debris flow in Jiangjia Gully. It has forecasted the next potential catastrophic year in which the annual sediment transport will be over the catastrophic. threshold 2 million m3. Furthermore, it has introduced the 'equal dimension-new information model', which makes the forecast be done continuously.
基金This research was partially supported by the Open fund projects of JiangXi Engineering Research Center of Water Engineering Safety and Resources Efficient Utilization(OF201603)Jiangxi Provincial Key Scientific Research Plan(Nos.20161BBG70051,20177BBG70046)+1 种基金National Natural Science Foundation of China(Nos.41641023,51869012)Jiangxi Provincial Department of Education Science and Technology Research Project Project(No.GJJ151124).
文摘This study proposes a comprehensive method,which consists of field investigation,flume test and numerical simulation,to predict the velocity and sediment thickness of debris flow.The velocity and sediment thickness of the debris flow in mountainous areas can provide critical data to evaluate the geohazard,which will in turn help to understand the debris runout.The flume test of this debris prototype can provide friction coefficient and viscosity coefficient which are important for numerical simulation of debris flow.The relation between the key parameters in the numerical modelling using the Voellmy model and debris-flow rheology is discussed.Through simulation of a debris flow that occurred in Luzhuang gully,it is observed that the debris flow runout determined by the Voellmy model was well consistent with that obtained from field investigation and flume test,demonstrating the effectiveness of this study.The relationship between the Voellmy model and debris flow runout is also proposed.
基金funded by the Second Scientific Expedition to Qinghai-Tibet Plateau (Grant No.2019QZKK0902)the National Natural Science Foundation of China (Grant No.42201095)+2 种基金the Natural Science Foundation of Sichuan (Grant No.2022NSFSC1032)the Sichuan Provincial Transportation Science and Technology Project (2021-A-08)the Key science and technology projects of transportation industry (2021-MS4-104)
文摘To accurately predict impact loads can ensure the safe operation of debris flow control projects.The instantaneous impact process is usually considered in the calculation of the debris flow impact force;however,the redistribution of an impact load after structural regulation is unclear.In this study we deduced the theoretical calculation of a debris flow impact on a double-row slit dam,and carried out a verification experiment on the debris flow impact.The calculation model considers the influence of the debris flow properties,dam arrangement and pile material.The results show that the impact force of the debris flow is obviously affected by the bulk density.When the bulk density is 21 kg/m^(3),the maximum impact force on the pile dam is 1.15 times that when the bulk density is 15 kg/m^(3),but the time it takes for the debris flow to pass through the dam body is reduced by 60%.The larger the relative pile spacing,the more sufficient the flow space and the lower the maximum impact force.The maximum impact force of relative pile spacing of 0.8 is 12%less than that of elative pile spacing of 0.5.The horizontal distribution of the impact force in the mud depth range is parabolic.The maximum impact force on the centre pier is 1.3 times that of a side pier,and the maximum impact force on the dam body appears at the top of the mud depth range.From the vertical distribution of the impact force,the maximum impact force at the highest mud mark is approximately 70%of that of the bottom.With the increase in the relative pile spacing,the longitudinal maximum impact force distribution first decreases and then increases.
