Model Test Study On Source Replenishment Mechanism Of Loess Mud Flow

Mud flow is one of the main types of geological hazards in the loess area.Sufficient provenance is a necessary condition for the formation of mud flow.The supply of mud flow provenance includes two aspects: erosion of channel by runoff and plugging and erosion of landslide weir.In this paper,the recharging mechanism of loess mudflow was explored by means of loess channel scouring test and weir plugging test.The research results can provide some theoretical support for the study of the formation mechanism of loess mudflow.Finally,there are the following conclusions:(1)Loess mudflow provenance includes two types: erosion provenance and plugging provenance.The erosive source is generated by runoff erosion,which is distributed in a relatively wide area and exists normally.It can not only become the source of solid matter of mud flow,but also affect the stability of channel slope before the formation of plugging event.The plugging provenance is generated from the disintegration of the weir plug body,and it is the main component of the mud flow provenance that takes part in the plugging event all the time,generally accounting for more than 3/4 of the total provenance.(2)There is a positive correlation between runoff erosion capacity and runoff and slope.The change of erosion capacity is reflected in the fluctuation of sediment concentration in runoff.The runoff carries away the sediment in the gully and causes gully and gully to be washed in different degrees.The stronger the runoff erosion ability is,the greater the change degree of gully bed morphology is,and the more obvious the deterioration effect on the stability of gully slope is.(3)In the process of weir plug outburst,the larger the runoff and slope is,the more obvious the outburst amplification effect is.The process of the weir block outburst is carried out in the form of traceability erosion and surface scouring.The traceability erosion reaches the stage of rapidly empties the reservoir capacity of the barrier lake after facing the water surface,and the erosion effect reaches the maximum.The widening of the crevasse of the weir plug is carried out in the form of progressive collapse,and the crevasse of the crevasse of the crevasse will be quickly decomposed away by runoff,and it will also cause secondary plugging when the scale is large.(4)The sediment yield per unit time in the scouring stage is positively correlated with the discharge and slope,while the sediment yield in the plugging stage is positively correlated with the discharge.Restricted by the size of the weir block,the ratio of blockage and sediment yield is negatively correlated with the flow.In the scour stage,the flow rate is maintained at a stable level,while in the plugging stage,the flow rate and the magnification coefficient fluctuate synchronically.The maximum magnification coefficient in the plugging process tends to decrease with the increase of the flow rate and slope.