Research On The Progressive Failure Mechanism For Slope Based On Centrifuge Model Test

Cause of the vast territory and the complex landform of China,where had a large number of manual digging and natural slope,was one of the most severe country of landslide problem.Geological disaster was caused by slope instability emerge in endlessly.With years of observation,experiment and research,the result shows that landslide failure was not instantaneous,but progressive,which had a strong intermittent.Therefore,studying and mastering the regular pattern of the slope progressive failure could help taking appropriate corresponding reinforcement measures in one or a few stages of slope failure.It would also reduce or even avoid the loss.In order to verify theregularity and mechanism of slope progressive failure,using the chengdu university of technology of TLJ-500 large geotechnical centrifuge modeling of the process simulation of the slope progressive failure,the main research results are as follows:1.The analysis through the displacement field of slope lateral position shows that: for the x-axis of the displacement analyzing,a traction typle of failure was presented to the bottom of the slope.The first failure was begin from the bottom of the slope,where was not sliding by itself.The region of stress concentration was also first produced from the bottom of the slope.And then that caused the plastic deformation and the reducing of bearing capacity.The upper section of the thrust type of the bottom of the slope was greater than the anti-sliding support.With the development of gradually upward,the whole slope was in failure.For the y-axis of the displacement analyzing,a thrust typle of failure was presented to the top of the slope.he first failure was begin from the top of the slope.Due to the increase of gravitational acceleration,the upper slope was failed by the increasing of the residual thrust gradually and the it was produced to the lower place.Then the whole slope was in failure.Through the analysis,the result shows that,the experiment on slope progressive failure was caused by the traction type of failure of the bottom and the thrust type of the top of the slope.2.The analysis through the displacement field of slope table position s hows that: landslide failure was not instantaneous.Partial failure was appeared from the bottom of the slope and that caused the producing transverse displacement from the bottom part firstly.With extended gradually,the failure was produced from the central of the landslide to the top,and in this process,this leads to the displacement.The research of the observation point shows there was a big difference between the frontal edge and the leading edge of the displacement of landslide.Because of the increasing gravitational acceleration,the slope failure was creeped and thrusted and the whole slope went forward.3.For analysing the deformation,failure state and the laws of tress field inside the slope,according to the soil pressure sensors which were installed in the experimental slope,the result shows that: The differences were unconspicuous between each pressure sensors at the accelerating intial phase.With the increase of the slope progressive failure and the gravitational acceleration,the internal stress field of the slope increased.That was due to the stress concentration of the slope deformation from the bottom of the slope which was begin to produece,and the slope of tractional deformation went forward.After the failure of the slope,the biggest soil pressure was appeared to the leading edge of landslide,and that meant to the deep creep mechanism of landslide.These validated the mechanism of creep–traction of slope deformation and failure.4.According to the experiment of direct shear test of soil which was nearing the sliding shows that: soil cohensive strength did not exist after the landslide.In the process of sliding,the effective cohensive strength of soil which was on the surface of the slide was gradually reduced to zero,while the effective angle of internal friction also decreased significantly.Overall stability coefficient of slope was decreased with the decreasing shear strength.5.The search of the dynamic strength reduction method on progressive failure for slope also shows that: dynamically reduction of the strength parameters of the local breakage slope that made the potential sliding surface of the slope progressive evolution to breakthrough.That truly represented the formation process of the potential sliding surface of slope.