Research On Seepage Characteristics And Stability Of Residual Soil Slope Under The Condition Of Ice And Snow Melting In The Short-term Frozen Soil Zone

The ablation and infiltration of ice and snow is one of the important factors to induce slope failure in winter.Although the northern part of Fujian Province is a region where the snowfall belows northwestern region in winter,there is a large temperature difference in the region.The most of melting and infiltration of snow is short-term.And the large porosity of residual soil slope causes macropore flow easily.These characteristic will give rise to the shallow instability collapse disease in turn,these issues cause adverse effects on the operation management of highway.However,the related basic theory has not been enough.Based on above,this article combined the methods of the literature and laboratory tests,numerical simulation,obtained the moisture and mechanical parameters of residual soil,proposed degree-day model which is suitable for the northern part of Fujian Province,revealed the percolation mechanism and residual soil slope stability of unsaturated and macroporosity flow in the condition of the ablation of ice and snow on the basis of these parameters and model.The main conclusions are as followed:(1)The contrast analysis of the different degree-day models showed that the distributed degree-day model from Hock could simulate the snow melting accurately.A combination of meteorological data could modify the degree-day factor and get the model parameters which suit for the northern part of Fujian Province as followed,the atmospheric pressure ranges from 97kPa to 103kPa;the temperature ranges from 3?to 8?;the zenith angle ranges from 41.3 ° to 48.5 °;the solar azimuth ranges from 33.9° to 38.9°;the estimation of thickness of the ice and snow could get the intensity of ice and snow melting infiltration ranges from 18mm/d to 50mm/d which is verified by using the Hock model.(2)Combined laboratory tests about the residual slope and numerical simulation showed that increasion of the intensity of snow melt infiltration and reduction of the angle of slope cause increasing the moisture content for unsaturated seepage.(3)The peak moisture content of macropore domain is higher than matrix domain at the same depth in residual soil slope for macropore flow,the maximum difference is about 18.3%.The matrix domain which is closer to macropore domain is faster than the further one in growth rate of soil moisture content.The closer one is prior to the further one 2.5h for response time to the infiltration.The former one is about 3.2%higher than the latter one at the peak moisture content.(4)The unsaturated flow has little influence on sliding surface of slope in the early stage of the snow melt infiltration.Critical slip surface gradually moves to the slope surface later.The falling range of safety factor is 6.9%;The slip surface moves faster to slope surface.in the condition of macropore flow,The falling range of safety factor is 14.8%;Both of them performance shallow damage in the form of slip surface.The macropore flow has larger influence on slope safety factor than unsaturated flow.(5)The increasing on diameter and bending rate of macropore will cause decrease of slope safety factor,but has little influence on safety factor and sliding surface.When the density of macropore varies from sparse to dense,the performance of slope safety factor is decreasing firstly and then increasing.There is a critical point in the influence on slope safety factor for changing of macropore density.The increase of the intensity of the snow melting will cause decrease of slope safety factor,and the slope safety factor of the macropore flow is decreased by 3.3%compared with the unsaturated flow.