Assumptions

This section simplifies the original problem and helps in developing the theoretical models by filling in the missing information for the physical system. The assumptions refine the scope by providing more detail.

Slip-Surface-Concave: The slip surface is concave with respect to the slope surface. The (\({\boldsymbol{x}_{\text{slip}}}\), \({\boldsymbol{y}_{\text{slip}}}\)) coordinates of a slip surface follow a concave up function. (RefBy: IM:crtSlpId.)

Factor-of-Safety: The factor of safety is assumed to be constant across the entire slip surface. (RefBy: GD:mobShr.)

Soil-Layer-Homogeneous: The soil mass is homogeneous, with consistent soil properties throughout. (RefBy: GD:sliceWght, GD:resShr, and LC:Calculate-Inhomogeneous-Soil-Layers.)

Soil-Properties: The soil properties are independent of dry or saturated conditions, with the exception of unit weight. (RefBy: GD:resShr.)

Soil-Layers-Isotropic: The soil mass is treated as if the effective cohesion and effective angle of friction are isotropic properties. (RefBy: GD:resShr.)

Interslice-Norm-Shear-Forces-Linear: Following the assumption of Morgenstern and Price (morgenstern1965), interslice normal forces and interslice shear forces have a proportional relationship, depending on a proportionality constant (\(λ\)) and a function (\(\boldsymbol{f}\)) describing variation depending on \(x\) position. (RefBy: GD:normShrR, IM:fctSfty, IM:nrmShrFor, and UC:Normal-And-Shear-Linear-Only.)

Plane-Strain-Conditions: The slope and slip surface extends far into and out of the geometry (\(z\) coordinate). This implies plane strain conditions, making 2D analysis appropriate. (RefBy: GD:srfWtrF, GD:sliceWght, GD:resShr, GD:effNormF, and GD:baseWtrF.)

Effective-Norm-Stress-Large: The effective normal stress is large enough that the shear strength to effective normal stress relationship can be approximated as a linear relationship. (RefBy: TM:equilibrium and UC:2D-Analysis-Only.)

Surface-Base-Slice-between-Interslice-Straight-Lines: The surface and base of a slice are approximated as straight lines. (RefBy: GD:srfWtrF, GD:sliceWght, GD:baseWtrF, TM:mcShrStrgth, DD:slcHeight, DD:angleB, and DD:angleA.)

Edge-Slices: The interslice forces at the 0th and \(n\)th interslice interfaces are zero. (RefBy: IM:intsliceFs, IM:fctSfty, and IM:nrmShrFor.)

Seismic-Force: There is no seismic force acting on the slope. (RefBy: IM:fctSfty, IM:nrmShrFor, and LC:Calculate-Seismic-Force.)

Surface-Load: There is no imposed surface load, and therefore no external forces, acting on the slope. (RefBy: IM:fctSfty, IM:nrmShrFor, and LC:Calculate-External-Force.)

Water-Intersects-Base-Edge: The water table only intersects the base of a slice at an edge of the slice. (RefBy: GD:sliceWght and GD:baseWtrF.)

Water-Intersects-Surface-Edge: The water table only intersects the slope surface at the edge of a slice. (RefBy: GD:srfWtrF and GD:sliceWght.)

Negligible-Effect-Surface-Slope-Seismic: The effect of the slope of the surface of the soil on the seismic force is assumed to be negligible. (RefBy: GD:momentEql.)

Hydrostatic-Force-Slice-Midpoint: The resultant surface hydrostatic forces act into the midpoint of each slice surface and the resultant base hydrostatic forces act into the midpoint of each slice base. (RefBy: GD:srfWtrF, GD:momentEql, and GD:baseWtrF.)