Compaction Loess Strength And Permeability Anisotropy Of The Research

Compaction loess is the layered soil.Vertical soil compaction loading makes along different directions with different structure, which leads to soil strength and permeability having obvious anisotropy. It is importantly influence on loess engineering strength and stability and this research is still lacking. Based on this, the paper carries out the research work about strength of compacted loess and permeability anisotropic problems.It cuts samples from the clods of compaction vertical and horizontal, respectively by indoor direct shear test to study the strength of anisotropy. Test results show that the shearing strength of the vertical and horizontal exist obvious differences. The shear strength of vertical and horizontal normal stress difference increases with the dry density; Under the high stress and the dry density increase its amplitude decreases.Under the same dry density, the greater the moisture content of the sample, the horizontal and vertical shear strength are smaller difference. moisture content and dry density change the internal friction Angle,the cohesive force of impact is bigger. Vertical direction of the cohesive force is greater than horizontal; With the increasing of moisture content, the cohesive force of difference between the two direction decreases.Under the small dry density, the compaction loess cohesive force anisotropy is not obvious.But large cohesive force of anisotropy is more obvious.It studies the permeability anisotropy by GDS penetration test. Under the same dry density, horizontal permeability coefficient is bigger than vertical. This may be due to the loess in the sheet, acicular particles in the process of sample preparation to directional horizontal arrangement. Dry density of compacted loess with different directional permeability coefficient influence significantly and with the increasing ofdry density, permeability anisotropy of the compaction loess decreases. In order to study the permeability coefficient of different depth, through confining pressure indirectly reflect the change of void ratio of soil under the gravity stress. Confining pressure of compacted loess has obvious effects of permeability coefficient of different direction,but the permeability anisotropy at the 50 kpa stage of the confining pressure. At the100 kpa to 200 kpa phase, permeability anisotropy is weakened; The increasing of dry density and confining pressure help to weak the anisotropy of compacted loess.Further considering the compacted loess under the condition of anisotropic,ABAQUS is used to simulate the influence of rainfall on the slope moisture field distribution. Simulation results show that the moisture permeability anisotropy is advantageous to the slope of the migration, plastic deformation also greatly weakened,and that will leads to free surface flat, advantageous to the dissipation of pore water pressure. Overall permeability anisotropy of the distribution of pore water pressure in the slope, the position of saturation line, stress and strain have great influence, changed the slope soil mechanics properties.So the material seepage parameters of anisotropic taken into account in actual engineering analysis is more reasonable, more press close to.