| Loess landslide is a typical geological disaster type in western China,high frequency and short time rainfall in summer is the key reason of loess landslide.In recent years,geophysical detection methods have been gradually popularized in slope stability monitoring,but there are few research achievements on multi-physical field parameters of special soil slopes under rainfall conditions.Therefore,it is of great theoretical and practical significance to carry out indoor physical model test of loess landslide under artificial simulated rainfall condition.Jingyang county in Shanxi Province southern tableland of landslide was used as a research background,an accord with the local characteristics of slope of indoor physical model on the loess slope was established,more than a set of artificial rainfall simulation system and physical field monitoring of the test platform was developed,in line with the intermittent type rainfall condition of loess landslide evolution indoor monitoring test was successfully carried out,The variation law of geoelectric field and strain field in slope body at different stages of landslide evolution is dynamically observed,the variation characteristics of loess microstructure before and after subsidence are tested and analyzed,and the response characteristics relationship between slope body shape and internal geophysical field at different stages of landslide evolution is established.The main contents and conclusions of the experiment are as follows:(1)Physical simulation of sliding failure process of loess landslide under intermittent rainfall was carried out,and the variation characteristics of wet front and slope body shape in the whole process of landslide evolution were analyzed.The results show that the migration speed of wet front is positively correlated with rainfall intensity,and the slope deformation follows the development law of slope top subsidence,slope shoulder slip,slope erosion and surface erosion.(2)The response characteristics of each physical field in the slope at different rainfall stages were analyzed by monitoring the change data of excitation current,spontaneous potential and strain in the slope.When the excitation current is close to 40 m A,the slope is completely collapsible.There are many controlled factors of spontaneous potential,but it has no obvious effect on the direction of water migration.The position of H2 layer fiber is most affected by landslide deformation,and the tensile strain value reaches 8000με,and the strain variation on both sides of slope is different.(3)Scanning electron microscopy(SEM)and particle size distribution test can be used to analyze particle morphology,pore type and particle size distribution before and after soil subsidence.Before collapsibility,skeleton particles mostly exist in the form of aggregate,and the particle structure is relatively loose,mainly in the form of overhead pores.After the subsidence,the overhead pores were destroyed,the aggregates were gradually decomposed,and the soil samples were compressed.With the increase of soil subsidence,the percentage of small particle size smaller than 0.005 mm in slope surface soil increases.(4)The characteristics of landslide deformation evolution are significantly correlated with the variation of geoelectric field and strain field parameters.At the stage of slight subsidence on the slope top,the current below the slope top is 20 m A and no obvious strain is generated.In the fracture propagation stage,the current value in the parallel slope direction reaches 25 m A,and the tensile strain value in the slope reaches3000με.The current value increases to 35 m A,and the tensile strain value increases to7000με.Deformation and failure stage: the compressive strain of-400με appears on the slope,and the strain values in other parts decrease.Figure [52] Table [6] References [121]... |
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