Study On The Model Test Of Loess-bedrock Interfacial Landslide In Yan'an

In Yan'an,geology hazards occur frequently for its vulnerable geological environment.especially loess landslides widely distributed,thus threatening the people's life and property and the development of economy.Among the landslides,loess-bedrock interfacial landslides are the most common form.The interface dip angle is close to horizontal,which is less than landslides' integrated internal friction angles.It seems like landslides shouldn't occur theoretically;nevertheless,there are many instances of this type,such as Xiaobiangou,Erzhuangke,Dingjiagou,Wangjiagou..In this paper,Xiaobiangou is regarded as studied object,and the mechanism and evolutionary process of loess-bedrock interfacial landslides are researched by model test.Some valuable results obtained are discribed as follows:(1)Based on uniform design,ignoring the correlation among the influence factors,the sensitivity analysis of loess-bedrock interfacial landslides stability is carried out with unit weight,angle of internal friction,cohesion,slope high,the ratio of slope,duration of rainfall and rainfall return period are selected as the influencing factors for test design.By means of step regression analysis method,and they can be sorted by step sizing factor.It is found that angle of internal friction,slope high and the ratio of slope are sensitive,but others are insensitive.(2)The similarity rule is deduced by using dimension analysis and model test system of loess-bedrock interfacial landslides is designed.Some parameters are monitored;for example,horizontal earth pressure,vertical earth pressure and pore water pressure.(3)The failure mode of loess-bedrock interfacial landslides is creep sliding-tension cracking on the condition of rainfall.The processes of deformation and failure are surface creeping,slope toe collapse,trailing edge cracking,general slide failure and crack expansion,the front being in compression uplift and the center of gravity reducing.