Leakage from buried drainage pipes can cause underground road damage and eventually lead to the formation of cavities.Additionally,rainfall increases the probability of collapse disasters.However,the processes by whic...Leakage from buried drainage pipes can cause underground road damage and eventually lead to the formation of cavities.Additionally,rainfall increases the probability of collapse disasters.However,the processes by which rainfall and pipeline leakage lead to water infiltration and subsequent migration of underground soil-thereby forming cavities-are not well understood.To address this challenge,we developed a physical model to simulate the soil erosion and migration process.This model,which incorporated both model testing and theoretical analysis,simultaneously simulated the effects of rainfall and pipeline leakage on soil erosion and migration.In addition,particle-level optical tracing microscopy was used to investigate the mechanisms of rainfall-and leakage-induced debonding and migration of soil particles and to analyze the characteristics of soil migration and critical gushing.Results revealed that pipeline-leakage-induced soil erosion weakened the bonds between soil particles surrounding the pipes and caused the initial opening of cracks between particles,the fluid began to diffuse from these initial openings,forming ice-flower-like patterns around the point.Under leakage conditions,the microchannels of runoff were interconnected,and the migration of eroded soil exhibited a gridded distribution of soil agglomerates.Moreover,a critical velocity of erosion migration occurred,once this threshold was exceeded,the dispersal of water and soil medium led to the instability of the soil structure.Rainfall and leakage intensified the formation of runoff channels and expanded the cross-sectional areas of these channels.The merging of infiltrated rainwater and leakage flow initiated the gushing of pipe-flow soil.The critical time of gushing in the test environment was approximately 46%earlier than that in the same period of the only-leakage condition.The average area of pits formed by soil collapse was also increased by approximately 105%.Furthermore,the soil erosion and migration process comprised three stages:debonding,migration,and gushing.Rainfall infiltration and leakage-induced erosion synergistically formed soil cavities,intensifying underground soil loss.The soil cavities expanded upward,causing the ground surface to collapse.An"e"-shaped vortex halo formed around the pit created by the collapse of the ground surface,leading to secondary collapses.The findings of this study provide a scientific foundation for the prevention and control of road collapse.展开更多
Effective migration system of coalbed methane(CBM)reservoir,which was controlled by development degree and opening-closing degree of fractures,determines the permeability of coal reservoir and can be characterized by ...Effective migration system of coalbed methane(CBM)reservoir,which was controlled by development degree and opening-closing degree of fractures,determines the permeability of coal reservoir and can be characterized by the pore-fracture system in the extrinsic form.In this paper,based on coal matrix elastic self-regulating effect theory and coal reservoir combined elastic energy theory,the fracture opening-closing degree parameterΔand the fracture development degree parameterξare suggested for the quantitative study of the effective migration system of CBM reservoir in southern Qinshui Basin.Further,the control functions ofξandΔto CBM enrichment and high production are discussed.The results show that in present stage the area with highξvalue is located in Anze and Qinyuan,and then Zhengzhuang and Fangzhuang,where fracture development degree is high.The area with highΔvalue is located in Zhengzhuang and Fanzhuang,and then Anze and Qinyuan,indicating where coal matrix elastic self-regulating positive effect dominates and fractures tend to be open.Through the comprehensive analysis onξandΔ,it can be found that their best match area is located in Zhengzhuang and Fanzhuang,with high values for fracture development degree and opening-closing degree probably bringing about high fluid pressure and good permeability of reservoirs,which are advantageous to an abundant CBM production.展开更多
基金supported by the Beijing Natural Science Foundation(JQ21028)the National Natural Science Foundation of China(52278326)the National High-Level Talent Program(SQ2022QB03353).
文摘Leakage from buried drainage pipes can cause underground road damage and eventually lead to the formation of cavities.Additionally,rainfall increases the probability of collapse disasters.However,the processes by which rainfall and pipeline leakage lead to water infiltration and subsequent migration of underground soil-thereby forming cavities-are not well understood.To address this challenge,we developed a physical model to simulate the soil erosion and migration process.This model,which incorporated both model testing and theoretical analysis,simultaneously simulated the effects of rainfall and pipeline leakage on soil erosion and migration.In addition,particle-level optical tracing microscopy was used to investigate the mechanisms of rainfall-and leakage-induced debonding and migration of soil particles and to analyze the characteristics of soil migration and critical gushing.Results revealed that pipeline-leakage-induced soil erosion weakened the bonds between soil particles surrounding the pipes and caused the initial opening of cracks between particles,the fluid began to diffuse from these initial openings,forming ice-flower-like patterns around the point.Under leakage conditions,the microchannels of runoff were interconnected,and the migration of eroded soil exhibited a gridded distribution of soil agglomerates.Moreover,a critical velocity of erosion migration occurred,once this threshold was exceeded,the dispersal of water and soil medium led to the instability of the soil structure.Rainfall and leakage intensified the formation of runoff channels and expanded the cross-sectional areas of these channels.The merging of infiltrated rainwater and leakage flow initiated the gushing of pipe-flow soil.The critical time of gushing in the test environment was approximately 46%earlier than that in the same period of the only-leakage condition.The average area of pits formed by soil collapse was also increased by approximately 105%.Furthermore,the soil erosion and migration process comprised three stages:debonding,migration,and gushing.Rainfall infiltration and leakage-induced erosion synergistically formed soil cavities,intensifying underground soil loss.The soil cavities expanded upward,causing the ground surface to collapse.An"e"-shaped vortex halo formed around the pit created by the collapse of the ground surface,leading to secondary collapses.The findings of this study provide a scientific foundation for the prevention and control of road collapse.
基金jointly supported by National Natural Science Foundation of China(Grant No.41272178)the Major Projects of National Science and Technology of China(Grant No.2011ZX05034)+1 种基金National Basic Research Program of China(Grant No.2009CB219605)"Qinglan"Project of Jiangsu Province
文摘Effective migration system of coalbed methane(CBM)reservoir,which was controlled by development degree and opening-closing degree of fractures,determines the permeability of coal reservoir and can be characterized by the pore-fracture system in the extrinsic form.In this paper,based on coal matrix elastic self-regulating effect theory and coal reservoir combined elastic energy theory,the fracture opening-closing degree parameterΔand the fracture development degree parameterξare suggested for the quantitative study of the effective migration system of CBM reservoir in southern Qinshui Basin.Further,the control functions ofξandΔto CBM enrichment and high production are discussed.The results show that in present stage the area with highξvalue is located in Anze and Qinyuan,and then Zhengzhuang and Fangzhuang,where fracture development degree is high.The area with highΔvalue is located in Zhengzhuang and Fanzhuang,and then Anze and Qinyuan,indicating where coal matrix elastic self-regulating positive effect dominates and fractures tend to be open.Through the comprehensive analysis onξandΔ,it can be found that their best match area is located in Zhengzhuang and Fanzhuang,with high values for fracture development degree and opening-closing degree probably bringing about high fluid pressure and good permeability of reservoirs,which are advantageous to an abundant CBM production.
