Due to sedimentation

particles in natural soil arrange anisotropically. Anisotropy diversifies the internal friction angles between relative sliding planes at different directions in soil material. Thus in failure analysis of anisotropic soil

except for conventional stress distribution coming from outside of material

strength distribution inside the material should also be taken into account in addition. Taking cross-anisotropic soil for example

failure mechanism considering both stress distribution and strength distribution is demonstrated. In the discussion

for simplicity

a linear relationship between the tangent value of the internal frictional angle of some planes in the cross-anisotropic soil and the spatial direction of the plane is presumed. For a cross-anisotropic soil sample in loading

when the condition that the stress state in somewhere of the sample achieves the strength where occurs at the first time

the cross-anisotropic soil sample is announced to be failed. Furthermore

more interesting results can also be obtained by analogy among the failure condition of three different typical materials which are metals

isotropic soils and cross-anisotropic soils. Failure occurs at the maximum shear stress plane for the metals

while for isotropic soils

the failure occurs at the maximum shear-compression ratio plane. Moreover

for cross-anisotropic soils

the failure occurs at the maximum shear-compression-strength ratio plan.