In this paper, a grid-based distributed hydrological model BTOPMC （Block-wise use of TOPMODEL） is introduced, which was developed from the original TOPMODEL. In order to broaden the model＇s application to arid regi...In this paper, a grid-based distributed hydrological model BTOPMC （Block-wise use of TOPMODEL） is introduced, which was developed from the original TOPMODEL. In order to broaden the model＇s application to arid regions, improvement methodology is also implemented. The canopy interception and soil infiltration processes were incorporated into the original BTOPMC to model event-based runoff simulation in large arid regions. One designed infiltration model with application of time compression approximation method is emphasized and validated for improving model＇s performance for event hydrological simulations with a case study of Lushi River basin.展开更多
Infiltration–runoff–slope instability mechanism of macropore slope under heavy rainfall is unclear.This paper studied its instability mechanism with an improved Green–Ampt(GA)model considering the dual-porosity(i.e...Infiltration–runoff–slope instability mechanism of macropore slope under heavy rainfall is unclear.This paper studied its instability mechanism with an improved Green–Ampt(GA)model considering the dual-porosity(i.e.,matrix and macropore)and ponding condition,and proposed the infiltration equations,infiltration–runoff coupled model,and safety factor calculation method.Results show that the infiltration processes of macropore slope can be divided into three stages,and the proposed model is rational by a comparative analysis.The wetting front depth of the traditional unsaturated slope is 17.2%larger than that of the macropore slope in the early rainfall stage and 27%smaller than that of the macropore slope in the late rainfall stage.Then,macropores benefit the slope stability in the early rainfall but not in the latter.Macropore flow does not occur initially but becomes pronounced with increasing rainfall duration.The equal depth of the wetting front in the two domains is regarded as the onset criteria of macropore flow.Parameter analysis shows that macropore flow is delayed by increasing proportion of macropore domain(ω_(f)),whereas promoted by increasing ratio of saturated permeability coefficients between the two domains(μ).The increasing trend of ponding depth is sharp at first and then grows slowly.Finally,when rainfall duration is less than 3 h,ωf andμhave no significant effect on the safety factor,whereas it decreases with increasingωf and increases with increasingμunder longer duration(≥3 h).With the increase ofω_(f),the slope maximum instability time advances by 10.5 h,and with the increase ofμ,the slope maximum instability time delays by 3.1 h.展开更多
In slurry shield tunneling,the stability of tunnel face is closely related to the filter cake.The cutting of the cutterhead has negative impact on the formation of filter cake.This study focuses on the formation time ...In slurry shield tunneling,the stability of tunnel face is closely related to the filter cake.The cutting of the cutterhead has negative impact on the formation of filter cake.This study focuses on the formation time of dynamic filter cake considering the filtration effect and rotation of cutterhead.Filtration effect is the key factor for slurry infiltration.A multilayer slurry infiltration experiment system is designed to investigate the variation of filtrate rheological property in infiltration process.Slurry mass concentration C_(L),soil permeability coefficient k,the particle diameter ratio between soil equivalent grain size and representative diameter of slurry particles d_(10)/D_(85) are selected as independent design variables to fit the computational formula of filtration coefficient.Based on the relative relation between the mass of deposited particles in soil pores and infiltration time,a mathematical model for calculating the formation time of dynamic filter cake is proposed by combining the formation criteria and formation rate of external filter cake.The accuracy of the proposed model is verified through existing experiment data.Analysis results show that filtration coefficient is positively correlated with slurry mass concentration,while negatively correlated with the soil permeability coefficient and the particle diameter ratio between soil and slurry.As infiltration distance increases,the adsorption capacity of soil skeleton to slurry particles gradually decreases.The formation time of external filter cake is significantly lower than internal filter cake and the ratio is approximately 3.9.Under the dynamic cutting of the cutterhead,the formation time is positively associated with the rotation speed of cutter head,while negatively with the phase angle difference between adjacent cutter arm.The formation rate of external filter cake is greater than 98%when d_(10)/D_(85)≤6.1.Properly increasing the content or decreasing the diameter size of solid-phase particles in slurry can promote the formation 展开更多
基金21st Century Center Of Excellence (COE) Program supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan
文摘In this paper, a grid-based distributed hydrological model BTOPMC （Block-wise use of TOPMODEL） is introduced, which was developed from the original TOPMODEL. In order to broaden the model＇s application to arid regions, improvement methodology is also implemented. The canopy interception and soil infiltration processes were incorporated into the original BTOPMC to model event-based runoff simulation in large arid regions. One designed infiltration model with application of time compression approximation method is emphasized and validated for improving model＇s performance for event hydrological simulations with a case study of Lushi River basin.
基金funded by the Natural Science Foundation of Fujian Province(Grant No.2023J011133)。
文摘Infiltration–runoff–slope instability mechanism of macropore slope under heavy rainfall is unclear.This paper studied its instability mechanism with an improved Green–Ampt(GA)model considering the dual-porosity(i.e.,matrix and macropore)and ponding condition,and proposed the infiltration equations,infiltration–runoff coupled model,and safety factor calculation method.Results show that the infiltration processes of macropore slope can be divided into three stages,and the proposed model is rational by a comparative analysis.The wetting front depth of the traditional unsaturated slope is 17.2%larger than that of the macropore slope in the early rainfall stage and 27%smaller than that of the macropore slope in the late rainfall stage.Then,macropores benefit the slope stability in the early rainfall but not in the latter.Macropore flow does not occur initially but becomes pronounced with increasing rainfall duration.The equal depth of the wetting front in the two domains is regarded as the onset criteria of macropore flow.Parameter analysis shows that macropore flow is delayed by increasing proportion of macropore domain(ω_(f)),whereas promoted by increasing ratio of saturated permeability coefficients between the two domains(μ).The increasing trend of ponding depth is sharp at first and then grows slowly.Finally,when rainfall duration is less than 3 h,ωf andμhave no significant effect on the safety factor,whereas it decreases with increasingωf and increases with increasingμunder longer duration(≥3 h).With the increase ofω_(f),the slope maximum instability time advances by 10.5 h,and with the increase ofμ,the slope maximum instability time delays by 3.1 h.
基金support from the Fundamental Research Funds for the Central Universities(No.2022YJS046)Joint Funds of the National Natural Science Foundation of China(Grant Nos.U1830208 and 52008021).
文摘In slurry shield tunneling,the stability of tunnel face is closely related to the filter cake.The cutting of the cutterhead has negative impact on the formation of filter cake.This study focuses on the formation time of dynamic filter cake considering the filtration effect and rotation of cutterhead.Filtration effect is the key factor for slurry infiltration.A multilayer slurry infiltration experiment system is designed to investigate the variation of filtrate rheological property in infiltration process.Slurry mass concentration C_(L),soil permeability coefficient k,the particle diameter ratio between soil equivalent grain size and representative diameter of slurry particles d_(10)/D_(85) are selected as independent design variables to fit the computational formula of filtration coefficient.Based on the relative relation between the mass of deposited particles in soil pores and infiltration time,a mathematical model for calculating the formation time of dynamic filter cake is proposed by combining the formation criteria and formation rate of external filter cake.The accuracy of the proposed model is verified through existing experiment data.Analysis results show that filtration coefficient is positively correlated with slurry mass concentration,while negatively correlated with the soil permeability coefficient and the particle diameter ratio between soil and slurry.As infiltration distance increases,the adsorption capacity of soil skeleton to slurry particles gradually decreases.The formation time of external filter cake is significantly lower than internal filter cake and the ratio is approximately 3.9.Under the dynamic cutting of the cutterhead,the formation time is positively associated with the rotation speed of cutter head,while negatively with the phase angle difference between adjacent cutter arm.The formation rate of external filter cake is greater than 98%when d_(10)/D_(85)≤6.1.Properly increasing the content or decreasing the diameter size of solid-phase particles in slurry can promote the formation
