Study On Rainfall Infiltration Characteristics Of Outwash Congeries In Jiuxiang

In southwest China with a large number of deposit formation and quaternary pleistocene outwash congeries,due to the constant change of the depositional environment in history,that the deposit has a complicated composition and structural characteristics.With the acceleration of western development and the construction of all kinds of large-scale projects,the construction of these accumulators is more and more unfavorable to the construction.Especially in the case of rainfall,it is very easy to induce geological hazards associated with outwash congeries.Therefore,it is of great theoretical significance and application value for the study of water accumulation body in the case of rainfall infiltration.In this article,through field investigation,and deposit in Jiuxiang area in ioutwash congeries of the composition,structure,characteristics,composition and permeability test and analysis,to be prepared for rain test.After that,the indoor rainfall test carried out in-depth research and analysis on homogenous accumulation body,crevasse accumulation body and coarse-grained aerial accumulation body,and the following conclusions were mainly drawn:(1)The outwash congeries is mainly composed of coarse particles and macroparticles,and the content of fine particles is relatively small,and local enrichment occurs.Under the influence of hydrodynamic conditions at different periods,the outwash congeries has obvious stratified structure in many parts.The mud cementation is commonly found in the cracks between coarse particles and giant particles,forming the form of coarse particles and giant particles as the skeleton and fine particles as the binder.(2)Field investigation and sampling analysis of outwash congeries deposits in Jiuxiang area.The non-uniformity coefficient of the outwash congeries in Jiuxiang area is much larger than 5,and the curvature coefficient is generally between 1 and 3.In the outwash congeries,four groups of rainfall infiltration tests were carried out.According to the obtained values,the permeability coefficient of the outwash congeries in the Jiuxiang areas was 0.0028cm/s.It lays the foundation for numericalsimulation.(3)The indoor experiments were carried out on three different kinds of outwash congeries,and the changes of moisture front,moisture content,matrix suction and pore water pressure were obtained.the simulation analysis was carried out.The following conclusions are drawn: in the beginning stage of rainfall,the water content and pore water pressure in theoutwash congeries appear in the small form;With the saturation at the bottom,the water content and pore water pressure of the outwash congeries show the upper and the bottom larger,while the middle part is smaller;In the fractured outwash congeries,the ratio of water content and pore pressure is closer to that of the crack,and the higher the value is,the larger the gradient is.The further the distance,the smaller the impact of the fissure;There is a clear relationship between the infiltration direction of rainwater and the overhead area.The flow direction shows the situation that the aerial area spreads to the surrounding area;The infiltration of rainfall is divided into three stages,namely: rapid infiltration stage;Stable infiltration stage;Diffusion infiltration stage.