Study On The Cause Mechanism Of Shallow Landslide Of Weak Metamorphic In The Qin-ba Mountain Region

Qin-ba mountain region lie in central of China. It stretches more than1600kilometers ineast-west direction, and acrosses Gansu, Shaanxi, Henan, Hubei and other provinces. There isactive geological structure, lithology overlap, distinct rainy season in the region, so that therehave a large number of shallow landslides. This study through on survey and analyse thedisaster environment and development law of shallow landslide in Ziyang county, tosummarize the development types and deformation-failure modes of shallow landslide. Onthis basis, it used uniaxial tests and triaxial tests and direct shear tests and shear rheologicalexperiments to reveal the deformation-failure mechanism of the landslide material and getthe physical and mechanical properties. The genetic mechanism of typical landslides aredetailed analysised from geologically and mechanical point of view. And slope stability iscalculated through limit equilibrium slice method and finite element strength reductionmethod. The main content of the paper include:1. The geological environment characteristics of the Qin-ba mountain region issummarized through on survey the geological environment and geological hazard andcombined with existing data. Focus on disaster background and distribution law of shallowlandslide in Ziyang country. Six major factors of induced slip are summed up. Four formationperiods of shallow landslide is divided into. And four stages of occurrence period are dividedinto according to developmental characteristics. Two failure modes and six forms of shallowlandslide are summed up. Common type of shallow landslides in Qin-ba mountain region isdivided into.2. The material of shallow landslide is weathering rocks and soil-rock mixture. So thelarge scale geotechnical compression and shear rheological testing machine is transformed forspecial test reach. Then the reasonable test methods and procedures are studied through thetentative experimentation, in order to reduce the error and obtain accurate parameters.3. There is mica-quartz schist in typical landslide from identification of rock mineralcomposition. The water-rock weathering mechanism is analysised to consider that is softmetamorphic rock according to the softening coefficient. The influence is obtained through thetests of wet and dry cycles on rock strength deterioration. The rock has water-swellingcharacter because of the rock containing kaolinite and vermiculite and other clay minerals.Thephysical and mechanical properties of the rock is studied through the routine testing of rock,point load test, uniaxial and triaxial compression test, and so on. 4. The physical and mechanical properties of soil-rock mixture of typical landslide arestudied through experiment. The influence of shear strength caused by moisture content andparticle size distribution and contact debris is studies. Then the empirical formula of shearstrength under many factors influence is proposed. The linear visco-elastic plastic creepconstitutive model is created through the shear rheometer test of soil-rock mixture. Themicroscopic deformation and failure mechanism of soil-rock mixture is studies through shearmodel tests and numerical simulation analysis.5. Through to map the geological profile and study the dykes and structuralcharacteristics of typical shallow landslide, the genetic mechanism is studies from geologicalperspective. The slope stability is calculated to use limit equilibrium slice method andstrength reduction of finite element method. The two kinds of method are all can be asshallow landslide stability calculation.