Table 1 Relationship of reduction coefficients for strength parameters of unsaturated soil²⁶.

Hefei Expansive Soil

C = 270.425e^−0.0771w

tanφ = 0.948e^−0.948w

0.9817

0.9754

F_φ = F_c^0.576

Xiaolangdi Landslide

C = 46.261e^−0.04172w

0.9953

F_φ = F_c^0.423

tanφ = 0.551e^−0.01764w

0.9573

Sanmenxia Landslide

C = 142.820e^−0.04388w

0.9922

F_φ = F_c^0.793

tanφ = 0.838e^−0.0348w

0.9458

Changsha Red Clay

C = 314.402e^−0.11338w

0.9086

F_φ = F_c^0.958

tanφ = 1.671e^−0.10863w

0.8927