Study On The Seepage Regulation Of Aggregate Gravel Soil On Slope Table

Talus landslides have a wide influence range,persistent harm to our life and a large eruption frequency,which is relatively a typical type of landslide disasters in our country.Aggregate gravel soils easy to induce landslide disaster,because aggregate gravel soil as material talus landslide sliding body have characteristics of strong water permeability,wide range of particle size and large porosity,etc.Therefore,by exploring the water movement characteristics in the gravel soil has theoretical guidance and practical significance for furtherly studying the mechanism of rainfall-induced landslide and prevention of geological disasters such as landslide.Aggregate gravel soil which had a complex material structure of quaternary soil and broken rock could explore different factors to effect of its permeability regulation by macro and meso aspects.Meanwhile,different size gravel of Aggregate gravel soil produced spatial variability under the geological movement through gravity,handling,erosion.The spatial distribution of different size gravel impact on the spatial distribution about hydraulic conductivity and water,resulting in the flow parameters of gravel soil presence spatial variability.Thereby affecting the slope of aggregate gravel soil shear strength reduction rate in different regions.In order to explore the relationship about aggregate gravel soil between the seepage characteristics and macro,meso pore characteristics,self-made instrument has been used for the gravel soil indoor and outdoor test close to Shuizuwan Tunnel.Simultaneously,CT scanning and image processing techniques would to be used in seepage analysis.The spatial distribution and spatial variability of infiltration characteristics about aggregate gravel soil has been study by geo-statistical methods.The main research results are summarized as follows:1.With the addition of moisture content,the porosity would firstly increased and then decreased.When the moisture content increased to 12.5%,the moisture content reaches to the maximum.Simultaneously,with the addition of moisture content,the gas porosity would gradually decreased and the small pores increased obviously,but the media pore and large pore decreased.The pore orientation angle under different moisture content are concentrated in 10°~30°,50°~70°,100°~120°,and 140°~160°,and the less moisture content,the less pore orderliness.Entropy probability and form factor prior probability with increasing the moisture content of a peak in the moisture content of between 7.5% to 10%,then with increasing the moisture content of is reduced.2.Surface void ratio is the most significant factor that affects the permeability coefficient.Simultaneously,with the reduction of containing stone rate(70%~30%),the void area variation coefficient,viod perimeter variation coefficient,void fractal dimension would firstly decreased and then increased.When the containing stone rate decreased to something,the permeability coefficient reaches to the minimum.Assuming that surface void ratio(x)and surface stone ratio(y),would fitted the permeability coefficient(k)formula: k=0.0328×x1.8245×y-1.4633.3.There is stepladder trend between wetting front and time curve.More specifically,wetting front migration rate will rapidly increase with the sudden increase of the topsoil moisture to a maximum(30~40mm/min approximately),then will slowly decrease with increased pressure.Finally the wetting front migration rate will slightly increase with the decreased pressure.The average rate of wetting front migration(without hydrops water)approach linear growth with the increased rainfall intensity.Development of soil settlement deformation passes through three stages: slow growth,sharply rises and gradually stagnation.The minimum time(approximately 50min)for sharp morph and sedimentation of gravel soil with the rainfall intensity is 2.0mm/min.There is a negative linear correlation between the permeability coefficient of gravel soil and the dry density.4.Kostiakov formula is used to simulate the infiltration process of gravel soil.Gravel mass fraction of different particle size,the infiltration rate and different depth of gravel soil moisture content have appropriate space interpolation accuracy by using gaussian,spherical and spherical model respectively.The particle size is larger than 10 mm gravel is mainly distributed in the top and middle slope region and the regional spatial variability of infiltration rate is relatively large.Small gravel(size 2 ~ 10 mm)accumulate in slope foot position.Saturated infiltration rate along slope from top to bottom gradually reducing the spatial distribution of trend.The slope waist moisture content is higher than the slope top and toe moisture content in shallow soil(0-15 cm),but the slope toe moisture content is higher than the slope top and toe moisture content in deep soil layer(15-25cm).The slope water content increased slowly with increasing depth.