The Infiltration Process Of Rainfall And Its Influence On The Accumulation Of Ice Water

Outwash accumulation is a kind of common Quaternary sediments in Southwest China,river bank slope,the scale is often greatly,a general volume one hundred thousand M ~ m ranging from tens of millions of fand fand sedimentary environment and conditions,the influence of the outwash congeries with complex composition and multi variable sedimentary characteristics.Rainfall infiltration is often an important cause of slope failure of this kind of deep accumulation layer.Therefore,it is important to study the infiltration process and infiltration mechanism of rainfall in the ice water accumulation reservoir to correctly evaluate the stability of the accumulation body.Based on the substance of accumulation of ice in the Dadu River,the sedimentary characteristics of the wide investigation,summarizes three typical structural features of body in ice water accumulation area(homogenous,heterogeneous type and fracture type)model,construct three physical experimental model,launched in three kinds of rainfall accumulation infiltration in the body of the procedure and the infiltration mechanism of more in-depth study,the main results are as follows:1.according to the field geological survey and research of the author,simply draw the Southwest(Liusha basin in the Dadu River,and Lancang river basin)outwash sedimentary characteristics as the main body layer,the composition of the material is more complex,the giant particles and coarse gravel,stone and gravel,sometimes between local the large particles filled with fine particles.Giant particles and coarse particles are closely fitted together,and there is seldom an overhead phenomenon.2.indoor rainfall test results show that the rainfall infiltration in the homogeneous accumulation process is a slow and stable change process,the infiltration from slope surface is simple,uniform downward infiltration,is divided into four stages: the stage of rapid infiltration,infiltration stage,stable stage,soil saturated infiltration stage.After the rain started,pore water pressure,volumetric water content and matric suction arrive at the wetting front after the rapid response,pore water pressure increases,the increase of water content,suction decrease,until it reaches the maximum,and began a slow recovery after the suspension of rainfall.During the test,the change of migration form of wetting front is the accumulation of surface wetting of accumulation body,slope migration and accumulation of bulk.3.heterogeneous model test,after wetting front reached the pore water pressure increases,the volume of the water content increases,the matrix suction decreased,but the variation in the heterogeneous model of homogeneous accumulation are very different,after the coarse grain region of pore water pressure and water content in the wet to Run Feng did not increase rapidly,rainfall after a pause,the water content of coarse particles decreased rapidly.During the migration of the wetting front,the soil particles in the coarse soil region change,forming a curve with smaller curvature radius,and the migration morphology is characterized by the slope migration,the irregular arc migration and the accumulation of the whole body.It is because of the uneven region exists,the rainwater infiltration channels in coarse particles in soil,high permeability,and the accumulation of other region where the infiltration rate is small,the coarse particles near the infiltration rate is relatively fast,change of coarse grain area of the soil pore water pressure and soil water content is also different.The infiltration law for the top of the hill infiltration phase,accelerated infiltration phase,uneven infiltration stage,soil saturation stage.4.in the fracture type accumulation body,due to the presence of cracks,resulting in the formation of uneven rainfall infiltration in the accumulation body,the pore water pressure makes the pore water pressure at the bottom of the cracks within the scope to be significantly greater than the other position of the same level.The infiltration mechanism is composed of three stages: the wetting surface of the accumulation body and the fracture,the rapid vertical seepage stage and the horizontal seepage stage.The presence of cracks change of infiltration channel rainwater,rainwater seepage is more complicated,especially the cracks at the bottom of the crack near the water content and pore water pressure with rapid increase to the peak at the wetting front,the matrix suction decreases rapidly.The wetting front moves down rapidly near the crack,and the change of form is the accumulation of surface wetting,two regular circular movement,the transition of wine cup shape to the accumulation of the whole body.5.Numerical analysis of combination of Dadu River Qing Gang Ju outwash accumulation,through cracks and cracks of two models under the assumption that,in case of no cracks,water in the process of infiltration in the clay layer(low permeability)above the formation of pore water pressure is very large,and the volume of water is large.In the case of cracks,cracks directly by rainfall infiltration,water to form larger pore water pressure and high rate of cracks in the bottom.During the rainfall,the slope stability coefficient without crack model decreased gradually after the rainfall,began to increase gradually;crack model in slope stability during rainfall will gradually decrease,but the minimum stability coefficient is less than the accumulation of cracks.It also confirms the rainfall infiltration pattern and mechanism of indoor rainfall test,heterogeneous model and fracture model.