Experimental Study On Debris Flow Initiated By The Slump Of Loose Soil In A Typical Dry Valley Area Of Southwest China

More and more studies have shown that drought is conducive to the development of geological disasters such as debris flow,which has brought severe challenges to our current monitoring and early warning of mudslides and the safety of people's lives and property in the dry valleys of southwestern China.However,in order to prevent and control such debris flow disasters,it is first necessary to recognize the characteristics and mechanical mechanisms of the initiation of debris flow by loose soil in arid valley areas.However,there are few domestic and foreign related results on the initiation of such debris flow.Therefore,starting from the experiment,this article attempts to reveal the mechanics mechanism and formation law of the debris flow caused by the collapse of the loose soil in the arid valley area.Through numerical simulation,the law of the safety factor of the slope under drought conditions is studied.This research helps people realize that in the past,in disaster warning and prediction,we focused on rainfall.However,through experiments and the distribution characteristics of domestic debris flows,soils are more likely to lose stability and initiate debris flows in the early arid climate.In terms of disaster prevention,attention should be paid to factors such as previous rainfall and temperature.Through the above research,the main conclusions are as follows:(1)The process of initiating debris flow in arid soil can be roughly divided into five stages: heavy rainfall infiltration stage,super-permeable runoff generation stage,particle erosion stage,soil slump stage,and debris flow initiation stage.Moreover,the initiation of debris flow is an unsaturated initiation,and the pore water pressure and water content have not reached the maximum value.(2)Under the same conditions of rainfall,slope,volume,etc.,a slope with arid and loose soil on the surface is easier to initiate debris flow than a slope without arid and loose soil on the surface,and the initiation duration is shorter,the scale is larger.(3)A slope with arid and loose soil on the surface is more conducive to the formation of slope runoff.The main reason is that the air inside the soil plays a role,forming a closed bubble,which affects the effect of rainfall infiltration.This kind of slope runoff will produce shear force along the direction of the slope while scouring the loose particles on the surface,dragging the surface soil,creating cracks,and the precursor of the debris flow is the large-scale landslide of the soil.Dilatancy failure;while the slope without loose soil on the surface has no such characteristics.The first is underground runoff,which continuously erodes the bottom of the slope,causing the slope to creep slowly.(4)By simulating the on-site slope safety factor,it can be known that the slope with dry loose soil on the surface is more prone to damage than the slope without dry loose soil,the lower the minimum safety factor,and the more dangerous slip surface.