= Angle of slope above the top of the wall measured from horizontal

= Net angle of broken back slope

= The wall friction angle assumed to be equal to zero

= Wall face batter measured from vertical

= Effective unit weight of soil

= Angle of internal friction; angle of shearing resistance

= Effective angle of internal friction

= Normal stress

= pi, which equals 3.1417

A_b = The cross-sectional area of the bolt at the end of the service life of the nail (considering corrosion)

A_c = The design cross-sectional area of the steel (defined as the original cross-sectional area minus corrosion losses anticipated during the design life of the wall)

A_i = Area of helix I

A_s = Area of vertical steel over the nails (negative moment) and at the midspan (positive moment)

b = Width of the beam (horizontal spacing between nails)

c = Cohesion of the soil

c'= Effective cohesion of the soil

C_F = Dimensionless factor to account for facing flexibility.

c_i = Effective cohesion at helix I

d = Distance from the extreme face of the shotcrete to the centroid of the reinforcement

D'_c = Effective cone diameter at the center of the facing

e = Eccentricity of resultant vertical bearing force (ft)

f'_c = Compressive strength of the concrete

FS = Factor of safety

F_H = Horizontal component of inclined earth force on wall

F_y = The yield stress of the steel

F_v = Vertical component of inclined earth force on wall

F_v = Shear strength of the steel

F₁ = Lateral earth force on wall

F₂ = Lateral surcharge force on wall

GOLDNAIL = Computer program developed to determine the stability of soil nail walls

H = Height of reinforced soil mass at wall or the height of a tieback wall as used on Figure 1.2.5 re: "Tieback Wall"

h = Height of reinforced soil mass at ends of nails

h_c = Thickness of the shotcrete facing

K_a = Coefficient of active earth pressure

L = Horizontal length of soil nails

M_c = Cantilever moment that the wall must resist

N_c = Bearing capacity factor for helical anchor in clay

N_qi = Bearing capacity factor at helix i

P = Pullout capacity

q = Surcharge loading on retained soil

q_i = Effective overburden pressure at helix i

R = Resisting force

s'= Effective shear strength of the soil

S_H = Horizontal nail spacing

SNAIL = Computer programs to determine the stability of soil nail walls

STABL

S_V = Vertical nail spacing

T = Tensile force provided by the screw anchor

V = Design shear strength

V_N = Punching shear strength of the facing system

W₁ = Weight of reinforced soil block

W₂ = Weight of slope above reinforced soil block

z_i = Depth from the ground surface to helix i