Numerical Investigation of the Pressuremeter Results Affected by Anisotropy of Geomaterials

Some geomaterials (soils and rocks) exhibit direction dependent linear elastic stiffness values due to their geological formation processes. This paper presents a numerical study, using ABAQUS finite element program, to investigate the effect of cross-anisotropy of geomaterials on the initial elastic pressuremeter response, in terms of K_i, i.e. the tangent to the initial portion of the Δ_p vs. ΔV / V_o curve, where Δ_p? is the change in the applied membrane pressure, Ä V is the change in the membrane volume due to the applied membrane pressure, and V_o is the initial volume of the membrane. The FE analysis results for the relationship between _i and the dip angle θ, defined as the angle between the plane of anisotropy and axis of the pressuremeter membrane, show that K_i increases with increasing sinθ up to 0.79 (i.e., θ=52°). Thereafter, K_i decreases slightly with increasing sinθ for the range between 0.79 and 1 (i.e., θ between 52° and 90°).