Seepage flow is one of the mainly hydraulic conditions for debris flow

different seepage discharges possess various seepage forces and scouring abilities which can induce different scales of debris flow. Through flume experiment

this study measures the pore water pressure by piezometer tube at three cross-sections

records the movement of fine particles and collapse process of coarse particles by high definition camera technology in micro respect

which is used to analyze the soil seepage fail and scouring effect in the process of debris flow formation. On this basis

conducting the experiment on fixing the slope angle of flume device is 7 degree and regulates the constant seepage flow discharge of 120

170

265 and 320 ml/s respectively

it analyzes the effect of the flow state on soil particles failure and debris flow initiation under different seepage flow discharges. The results indicate that the migration of fine sand particles and collapse of coarse particles which lead to the rearrangement of the soil structures and enlargement of the pore water pressure

are the important reasons for soil particles failure

initiation and scouring by low soil resistant; with increasing of seepage flow discharge

the flow velocity and pore water pressure increasing rapidly

it attained that the coarse particles fail to move are mainly affected by seepage force and flow scouring. Meanwhile

the movement of the soil particles and water flow shows three different flow states

i. c. presented slightly slide

transitional slide and rapid slide.