Physical Simulation Study On The Formation Mechanism Of A Medium Low-angle And Counter-tilt Slope With Rigid Layers On The Soft-Taking The Dazhai Landslide In Guanling County Of Guizhou Province As Example

A rare large high-speed landslide happened in Anshun, Guizhou. The landslidethat caused99people killed was named Dazhai landslide. Based on many researchesin site survey, reconnaissance and experiment, the engineering geological conditionsin landslide area and the internal mechanism of the landslide were analyzed cautiously.And the conceptual model was built. After that, the formation mechanism of Dazhailandslide was studied deeply with the methods of bottom friction experiment and3Dcentrifuge model experiment. The main results as followes:(1) Dazhai landslide appeared in the slope with medium-angle counter-tendencyrock formation. And the rock formation has the property that the higher one washarder than the low one. The upper layer is T1ysandstone with medium thichnessseam and the lower laywer is P3l+cmudstone strata of coal line wieh.Attitude of rockson the layer is N35°E/SE∠34°and attitude of rocks on LOWER is N40°E/SE∠30°.(2) Based on the properties of slope structure, landslide accumulation andlandslide motion, the landslide mode was set as ‘compress-tension fracture-toppleover-the locking section formed-the locking section broken’.(3) By bottom friction simulation test built the DaZhai slope instabilitymechanism similar model. Through the trial study of similar model, found there werefour stages in the evolution of deformation process: Soft layer compression-hardlayer compression deformation and compaction; hard layer cracking; hard layerbending and break; locking section found.(4) The large centrifugal model test were designed and completed. From thebeginning of the model structure and size of the design and the design of model similarity relation, the selection of model materials, the determination of ratio ofsimilar materials, measuring sensor selection and layout, to the model of productionand installation, test load and so on a series of work, a complete design method for the3D centrifuge model with similar rock formation was built.(5) Centrifugal model in detail under the high stress field characteristics ofdeformation and failure were detailed analyzed. Through displacement and earthpressure, monitoring data and detailed analysis of slope with cracks distribution,deformation of the slope can be divided into the upper cracking zone (compressionbending cracking belt)、central pressure caused by the shear zone、slope with thepressure of hard layer under section bending cracking such these three regions.Deepen understanding DaZhai landslide formation mechanism, the achievements andthe above qualitative analysis theories and bottom friction simulation conclusion isconsistent.(6) The thickness of strata, strata dip impact on deformation and failure of thegently dipping inner pair and Soft-type were discussed. The failure mechanism of thisslope was further deepened.