Numerical Simulation Of Slope Deformation Based On ANSYS

Relying on the National Key Basic Research and Development Program of China?973Program,NO.2013CB733200?for landslide monitoring in Lixian,Sichuan Province,this paper processes and analyses monitoring data,performs numerical simulation for movements of this slope using a finite element method based on static structural analysis of the software ANSYS,and gets results,as well as relationships between parameters of the model and rainfall.The main research contents,methods,and results are as follows.For monitoring results at different points,annual variations of the absolute displacement at point 8002 are 21mm,210mm,84mm for N,E,and U components respectively;at point8003 are 84mm,287mm,139mm;and at point 8004 are 88mm?401mm?146mm.All of the directions are negative for the N,E,and U component at each point.Direction of the maximum displacement points to the school beside the slope.Results also show larger displacements at higher altitudes,which is accordance with generic characteristics of a landslide.Large displacement distributes from June to September.Each month,the correlation coefficient of the E component displacement and last month's rainfall reaches 0.83⁰.86.Build a 3-D model of the slope in ANSYS for simulations using a finite element method;make elastoplasticity assumptions to the soil material;choose a D-P model as yield conditions,assign constant values for elasticity modulus E,Poisson's ratio?,cohesion C,internal friction angle?,and density?,and ignore the effect of volume expansion and temperature.Perform numerical simulations for surface movement of the slope in every month from August 2014 to August 2015 using the static structural analysis module in ANSYS.Geometric changes before and after simulation is big at the top and small at the bottom.Displacement vector shows that movement direction of the slope mainly points to the school and displacements are lager at higher elevation.Cloud maps of displacement change and distributions of stress and strain are acquired as well.Compare simulated and monitored displacements at monitoring points to check the coincidence level of simulation and actual situation;the correlation coefficient of them reaches 0.97 for the E component,and 0.75 for other components.Mean absolute errors of simulation for the E component are 2.88mm,2.48mm,and 4.51mm at the three monitoring points respectively;and the corresponding mean percentage errors are 18%,10%,and 17%.The simulations and monitoring results fit well,proving the reliability and veracity of the model.Verify that rainfall could affect material constants and boundary conditions,indirectly leading to movement of the slope.To be more specific,?1?when soil in natural state,in the absence of rain or very little rain?10mm or less?,E is 45MPa,?is 2100 kg·m^-3,C is 25kPa,and?is 24°,the monthly displacement of E component at the highest monitoring point is9¹6mm;?2?when rainfall reaches 20⁸0mm,with the increase of monthly rainfall,E,?and?decreases,C increases first and decreases later,the corresponding displacement is20⁵3mm;?3?when rainfall reaches over 80mm,the displacement becomes 50⁷7mm.Increase of rainfall also led to the increase of external loads,which decreases the soil strength,resulting in occurrence of slippage.