Study On Deformation And Failure Mechanism Of Typical Metamorphic Rock Slope In Wenchuan To Maerkang Expressway

Many problems were encountered in expressway construction in the mountains,the slope problem is always the most common one.In this thesis,the Wenchun to Maerkang Expressway is located in the Tibetan area of Sichuan,the metamorphic rocks are widely distributed in the area,the lithology of the slope along the expressway is mainly phyllite,slate and schist,the slope is steep and jointed,the strength is low,it is vulnerable to damage affected by the construction of project,it is of great significance to study the mechanism of slope structure and deformation failure.The main contents of this thesis are as follows:(a)Based on the data collection,investigate and analyze the structural types and the characteristics of deformation and failure of the slope in the study area;(b)Summarize the failure pattern of the slope,and analyze the factors that affect the slope stability,and then analyze the sensitivity of the influencing factors;(c)Taking bedding slope and anti-inclined slope as the examples,using the Universal Distinct Element Code simulate the deformation and failure progress of the two types of slopes after excavation and analyze its destruction mechanism.The main research results of this thesis are as follows:(1)Through the collection of regional data and field investigation and analysis,the study area slope structure is divided into three categories: layered structure,block structure and homogeneous structure.The layered structure includes anti-inclined layer,bedding and oblique layer;homogeneous structures comprising a bulk structure and a fractured structure.The slope failure mode is divided into five categories: dumping,cracking-slip,fall,stacking sliding and hole damage.(2)This thesis summarizes the factors that affect the slope stability in the area,including rock engineering geological conditions,topographic features,slope structure,water,human construction excavation,earthquake,weathering,freezing,thawing,rooting and so on.Then,the sensitivity of the gravity density,cohesion,the internal friction angle,the height of the slope,the angle of the slope and seismic acceleration are analyzed by the univariate analysis method,and the sensitivity is from the order of the friction angle,seismic acceleration,the height of the slope,the angle of the slope,gravity density and cohesion,the result show that the internal friction angle has the greatest effect on slope stability.(3)According to the numerical simulation results,the failure process of the two kinds of bedding slope and anti-inclined slope is divided into four stages: the excavation leads to the formation of the tensile cracks,the expansion of the cracks and the formation of the deformable body,the deformed body slips or dumps,destroyed rock mass piled on foot.Two kinds of damage patterns are mainly to tensile failure,shear failure occurs locally.The damage of the bedding slope begins at the foot of the slope,and the failure mode is traction sliding.The damage of the anti-inclined slope starts from the trailing edge of the crack and the failure mode is dumping.