Study On The Mechanism Of Failure And The Stability Of Ancient Debris Landslide

In order to analyze the stability of ancient debris landslide,reveal the factors of failure mechanism of ancient debris landslide and influence,and the data collection and field investigation are carried out.The physical and mechanical properties of gravel soil were analyzed by field test,indoor particle analysis and indoor triaxial compression test.through long-term monitoring,analyzed the deformation and variation of landslide;3D the numerical model of landslide using Civil 3D and ABAQUS,analyzed the stability of landslide and fluid solid coupling.Through the study,we can obtain the following achievements and understanding.(1)Through the analysis of the soil particles,the soil grading curve is discontinuous,and there is a phenomenon of particle size loss in0.1-0.5mm particles.Through a lot of triaxial compression test,stone content of landslide area of gravel soil physical and mechanical properties has a significant impact,including stone rate at about 60% there is a minimum,cohesion and stone content in the landslide area of gravel soil close to the values,with the increase of stone content showed a trend of decrease the internal friction Angle of the whole.This indicates that the occurrence of the landslide is related to the loss of particle size and the stone rate,which is the intrinsic factor of the landslide.(2)Through monitoring and analysis,the deformation of each point of the landslide is still growing,and the deformation is mainly in the rainy season,which indicates that the rainfall is the important inducing factor for the landslide of the mountain;in the monitoring points in the middle of the landslide,the level of displacement and verticaldisplacement was significantly greater than the rest of the point,and also appeared in the May to June the linear growth.Through field survey that the new cracks appeared over the top,which also verified the feasibility of monitoring.(3)Use Civil3 D to extract the natural elevation of the original topographic map,establish the 3D geological model of the landslide,and import the ABAQUS finite element software to establish the three-dimensional numerical model of the landslide.landslide using strength subtraction,finding the landslide stability coefficient of about1.03 at and the steady state.The results showed that the 3D model can completely consider the influence of landslide topography,and restore the original topography of the area.It is more close to the real situation of landslide than the traditional methods such as the three-dimensional simplified model and the unbalanced thrust method.It is a new way to analyze the stability of landslide.(4)The fluid solid coupling was analyzed by ABAQUS,and we can know that the rainfall intensity had a significant impact on the deformation of the landslide.But it will form obvious deformation and destruction only when the strength reaches a certain value;the deformation of the surface was obviously higher than that of underground deformation and landslide surface,surface and subsurface deformation size,direction and deformation have significant difference;Deformation with time when the rainfall intensity is small,slow growth,but when the rainfall intensity reaches a certain value,the landslide deformation increases quickly with time,the first time after the deformation will be basic remain unchanged,the landslide has been destroyed,explain the occurrence of landslide must meet certain rainfall intensity and rainfall time.(5)When the rainfall intensity was low,although the rainfallinfiltration led to the rise of underground pore water pressure,the pore water pressure will remain basically linear distribution;when the rainfall intensity reached the rain intensity,the pore water pressure will rise rapidly,becoming confused,the rainfall intensity at which time may be greater than the soil the infiltration capacity and surface runoff will occur.