Preliminary Research on Anisotropy of Mechanical Properties of Q_4 Loess in Lanzhou

The laboratory consolidation and direct shear tests were carried out to compare the shear strength parameters and deformation parameters of Q4 loess in Lanzhou from horizontal and vertical direction respectively,so as to explain the directivity effect on the mechanical properties of the loess.The results show that the anisotropy of mechanical properties of Q4 loess in Lanzhou is remarkable,especially when the normal stress is lower,but when the normal stress is getting higher,the relative differences between vertical and horizontal samplings are reduced.This has something to do with the structural strength in the vertical and horizontal directions of the loess.For the constructions that undergo the vertical loads such as the foundation,subgrade,and et al,the vertical sampling and relevant values are reasonable and safe,but for the slope,tunnel construction and underground structures,the anisotropy or directivity effect of loess should be carefully considered.