Study On The Slope Effect And Mechanical Impact Of Soil Moisture Migration And Temporal And Spatial Evolution On Loess High-Filling Slope

To address the problem of insufficient construction land and scarce agricultural land resources in the Loess Plateau region,major engineering projects such as hillside construction and gully treatment have emerged,resulting in a large amount of high-filling slope.These projects have alleviated the contradiction between human and land resources,but have also caused a series of ecological or water and soil disasters,such as regional ecological geological environment degradation,frequent shallow slope destruction,and increased soil erosion.Therefore,studying the spatiotemporal evolution and mechanical effects of soil water migration on high-filling slope in the Loess Plateau has good social and economic value.Taking the typical high-filling slope in the southern gully of Yan’an as the research object,based on a large-scale on-site monitoring system,combined with indoor experiments,data analysis,and numerical simulation calculations,this paper studies the dynamic and migration characteristics of soil water in high-filling slope under the influence of slope effect,and explores the relevant relationship between rainfall,groundwater,and shallow soil water in high-filling slope under the influence of slope effect,revealing the mechanical effects of water dynamics on slope stability.The specific research contents and conclusions are as follows:(1)The long-term soil-water dynamic and soil deformation characteristics of the highfilling slope were studied.Based on large-scale in-situ monitoring experiments on a loess highfilling slope,the monitoring data of about 36 months(from July 16,2019,to July 23,2022)were analyzed to clarify the seasonal fluctuations and distribution characteristics of rainfall and groundwater during the study period.The variation characteristics of soil volumetric water content and matrix potential were revealed,and the settlement deformation characteristics and trends of the slope were explored.(2)The study explored the spatiotemporal evolution characteristics of unsaturated soil water migration in a slope affected by the slope effect.Descriptive statistical methods,soil water potential theory,and zero flux plane theory were used to quantitatively analyze the relationship between volumetric water content,soil water potential,and soil water migration evolution.The spatiotemporal evolution characteristics of volumetric water content and soil water potential in the slope soil were clarified,and the migration and evolution motion law of soil water was clarified.Meanwhile,the response patterns and characteristics of soil water to different types of rainfall events were analyzed using time series methods,and the water infiltration and redistribution processes under different rainfall patterns were explored.(3)This article explains the multi-scale time-frequency characteristics and transformation relationships of soil moisture in the high-filling slope under the influence of rainfall,groundwater,and slope effect.Based on monitoring data such as rainfall,groundwater,and soil moisture at different depths,the wavelet analysis method is used to clarify the impact of rainfall,groundwater,and slope effect on the transformation relationships of various types of water in the slope from the frequency domain perspective.The main controlling factors affecting the transformation relationships of various types of water in the slope are determined,and the multiscale time-frequency characteristics of soil moisture are explored.(4)The mechanical effect of soil moisture dynamics on the shallow slope stability of a loess high-filling slope was revealed.Based on monitoring data of slope settlement,water content,temperature,and rainfall,the relationship between the annual deformation trend of the slope monitoring points and the water dynamics was clarified.Based on the direct shear test data,a simplified two-dimensional slope model was constructed using the finite element software ABAQUS.The consistency between the deformation trend of the model monitoring section and the deformation trend of the slope monitoring points on-site was verified,and the influence of water dynamics on local deformation and failure of shallow slope surface was investigated.