Indoor Model Experiment On Interfacial Landslide About Loess-mudstone Area In Inner Mongolia

Currently，the main research achievements about loess-mudstone interfacial landslidefocused on the shape and motion characteristics，the sliding soil characteristics and thefailure modes and stability analysis about the loess-stone composite slopes and so on，lacked of the study of slip mechanism，action characteristics and influencing factors aboutthe contact surface between loess and mudstone. Therefore，there were great theoreticaland practical significance to provide certain theories basis and practice guidance for theearly warning，report and project control about the landslide in this area.Experiment method adopt on semi similarity material indoor model test, samplingspot was in the contact zone of loess-mudstone area in Qingshuihe County，Huhhot，InnerMongolia, Researched on the startup condition and landslide mechanism about thelandslide on the interface of loess-mudstone with the rainfall effect and gained theachievements as followed.Determined the basic mechanical properties of the similarity material required in theexperiment with the method of indoor experiment， and provided data support fordetermining the similarity material，based on the study and analysis of the physicalmodel experiment theories，combined with the characteristics of the semi similaritymaterial landslide physical model experiment，derived and calculated the main parametersof the physical model experiment with the method of dimensional analysis，and gained thesimilarity conditions，researched the design method of physical model experiment for theloess-mudstone interfacial landslide， designed and established a semi similaritymaterial landslide physical model test system，composed with the experiment plat device，artificial rainfall device and data collected system， combined with the physicalmodel experiment theories，studied the interfacial landslide with the rainfall effect in theloess-mudstone area in Qingshuihe County，analyzed the change law of the stress field andseepage field in the progress of the landslide occurred and developed, revealed the slipmechanism with the rainfall effect in the loess-mudstone area: Rainwater permeateddownwards the loess layer after the rainfall, and gathered on the interface of theloess-mudstone to form a plastic flow weak layer, because the mudstone layer could beconsidered as an aquiclude compared with the loess layer. The loess layer collapsed alongwith the rainwater sustainable infiltration. At the same time, rainwater carried the loess on the plastic flow weak layer downwards the interface, so that the loess on the toe occurredhorizontal displacement, and lead to the volume reduction, because of the liquefactionphenomenon of the loess. The fracture occurred near the toe of the slope because thevertical displacement of the loess layer on the toe was larger than the others with thedouble function of collapsibility and seepage. The further development of the fracturealong the sliding surface guided the soil failure and slide at last. When the startup conditionwas met, it occurred interfacial landslide, otherwise it occurred loess internal landslide.Explored and proffered the conditions caused interfacial landslide: the minor rainfallintensity, the longer rainfall duration and the overlaying soil thickness generally not morethan3m. All the research provide theoretical basis and scientific guidance for the furtherstudy, early warning and project control.