Research On The Building Of Slope Model Based On PFC

China has complicated topographic features. In the process of construction,Especially in the large hydropower, highway project, people often encounter a lotof tall slopes. How to reasonably design the slope has become a key problem to beconsidered. Because of the complexity of rock and soil mass, it will require largeamounts of energy and resources by means of mathematical and physical methods.Today, in this rapidly changing world, the methods are also gradually being replacedby numerical simulation methods. In the process of simulating, one of the mostimportant factors to be considered, and also the most critical issue is how to build themodel. The establishment of a more reasonable model, will directly determine whetherthe design works are scientific and feasible. In most cases, during the highwayconstruction in mountainous area, engineers often use gravel or tunnelexcavation spoil and other granular material.For bulk materials, the use of discreteelement method of analysis are often more appropriate.In this paper, relying on the Open Fund Project (GZ2009-21) from the State KeyLaboratory of Geohazard Prevention and Geoenviroment Protection of ChengduUniversity of Technology, with the earlier data from the large scale triaxial test, tostudy the particle roughness effect, using PFC2D software. This paper introduces thesimulation principle of particle morphology and the roughness of the samples.Simutaneously, the generation process of the graded gravel numerical samples are alsointroduced. On this basis, with the embankment cross section of the Yalu highwayK112+908.16~K113+67as its basic outline, according to the need of research, thispaper build the numerical model of different proportion to the certain simplification.Without considering the water and the earthquake, under the action of gravity, thepaper analysis the deformation mode of the numerical model, while the stress level isconstant. According to the comparison, it finally obtains the relativelyreasonable model. By using the SIGMA/W module in Geo-studio and the softwarePFC2D as the research tool, this paper analyzed the deformation mode of prototype model and the model with the scale of1:100while the stress level are the same. It alsomade separately analyses from the transverse and longitudinal view. At the same time,this paper analyze the1:80and1:60aggregate model with PFC2D. Compared with the1:100model, the paper make a conclusion that the less of the model reduced multiple,the more reasonable results we will get. When it comes to the parameters, we used thedata from the project to make slope stability analysis with the finite element software,but made some change. As to the numerical simulation of PFC biaxial experiments, westill used various experimental data, including the particle analysis experiment, thecompaction test and the large scale triaxial test. We got the meso parameters of theparticle model and aggregate model by fitting. When the slope were analyzed usingthe PFC software, the parameters of embankment material from the fitting resultsbetween the biaxial tests and the large scale triaxial test were used. Other parametersare fitted with the results from the finite element method, combing with the projectreport. The main conclusions are as follows:1，Through the study of effects of roughness on the coarse grain soil, we draw thefollowing conclusion:Samples with clumps can simulate the Skeleton-pore structure of the gravelrealistically. The distribution of the contact force is very reasonable and uniform beforeloading. Mosaic texture between clumps can tremendously improve the strength ofthe sample. Deformation process reflects the irregular intergranular bite, slidingcharacteristics. Sample strength and grain roughness (namely the D4value) also has alinear proportional relationship. Samples’ initial coordinate number is one of thedecisive factors for the friction angle. The law of coordinate number of the samplewith clumps varying with the axial strain’s development reappears the microscopicmechanical properties of the granular material’s elastic deformation.2, According to the similarity theory, the paper analyzes what similarity criterionof the slope analysis should be followed in the third chapter while keeping the stresslevel unchanged. This paper also verified them through the finite element method. Thearticle also got microscopic parameters of the relationship between different PFCmodels. The main conclusions are: (a) In general, the product between the slope size and gravity acceleration isconstant, when the stress level is at the same time, keeping other conditionsunchanged, the ratio of the total displacement and the size of the model is a certainvalue.(b) For the PFC slope model, when the stress level is kept constant, the averageparticle radius is proportional to the particle modulus, the normal stiffness isproportional to the shear stiffness, the normal stiffness is proportional to the averageparticle radius. The wall’s normal stiffness is proportional to its shear stiffness.3, As to the slope composed of coarse grained soil bulk materials, the discreteelement method has obviously superiority.4, Whether to use the prototype model with the radius magnified, or the scalemodel with the radius unchanged, the magnification or reduction mainly depends onthe L/R value, the time the model generation and loading wasted, and the number ofcells. When the cells are much less, it will make significant effect to the results. Inthe actual slope model, even if in the scale model,2000particles is not enough tosimulate the slope.5, According to all the results, when the scale is the same, it is obvious that theaggregate model is better than the circular model. In the use of the original model, theaggregate model is be recommended. However, in the study of issue which is notsensitive to the deformation, the circular model of the original proportion can be used.6, According to the analysis, the1：100proportional model has a good consistentwith the actual situation. However, according to the research of this paper, the Stress inX direction of the1：80and the1:60proportional model is larger than the results fromthe finite method. Simultaneously, displacement of1:80aggregate model also has itsunreasonable place. Therefore, factors influencing the reasonable model scale andcalculation results needs further research.