Retaining Walls Analysis & Design

Analyze gravity and gabion retaining walls, from the oldest weight-based, reinforcement-free gravity wall to the modern gabion wall filled with rocks for low-cost landscape use.

Discover cantilever concrete retaining walls, including cost-in-place, precast, and concrete-filled blocks. See how the base-fixed cantilever enables faster, material-efficient walls for basements, bridges, and up to six meters backfill.

Explore how counterfort walls convert vertical soil pressures to horizontal forces, with stem and slab as a one-way member, and compare buttress walls that resist compression and 1.5–3 counterforce spacing.

Analyze vertical and horizontal forces on retaining walls, including wall weight, base weight, backfill and water pressures, and active and passive earth pressures.

Active earth pressure is soil movement pushing the wall away, driven by a sliding wedge and shear resistance. Lateral pressure equals vertical stress times a coefficient, contrasted with passive pressure.

Explain passive earth pressure by showing soil moves into the wall, opposite the active case, and how vertical principal stress multiplied by a passive coefficient yields the passive pressure.

Apply at-rest earth pressure for basement retaining walls with lateral restraints rather than active pressure, as restraint raises the pressure and many designs underestimate lateral soil load.

Analyze retaining wall stresses where active and passive pressures arise as the wall moves away from or into the soil, guided by sigma1, sigma3, and the K factor.

Calculate lateral earth pressure at rest using the Jaky 1944 empirical equation, with k0 from 0.4 to 2.6, and outline cohesion and shear strength implications for active and passive pressure.

Rankine theory explains active earth pressure on a vertical retaining wall, developed in the early 1970s, assuming a smooth wall, horizontal backfill, and neglecting friction with cohesionless soil.

Present the generalized Rankine active earth pressure for inclined backfill and wall, deriving active pressure angles and stresses with equations to compute z_active and the active force.

Clay backfill increases wall pressure due to water ingress through cracks, slow drainage, and higher moist unit weight, while its psychotropic behavior causes cycles of healing and new failures.

Explore Rankine theory for passive earth pressure on a vertical retaining wall with horizontal backfilling surface, and learn to derive passive pressure from the active equation by sign changes.

Explore Rankine active and passive earth pressures, including alpha inclination and the Indrani and Ganjgal 1997 relation, with the note that backfill is usually horizontal.

Examine Coulomb's active earth pressure theory and its assumptions: inclined backfill and wall surfaces, wall-soil friction, a failure plane through the heel, and the earth resultant inclined by friction angle.

Apply Coulomb theory equation to compute active earth pressure on retaining walls by locating the weight wedge, friction angle, and the resultant normal and shear forces.

Apply Coulomb theory to passive earth pressure, using the same force triangle and sign changes as active pressure, with soil weight, angles, and directions guiding the equations.

Analyze lateral earth pressure on retaining walls from surcharge, including line loads and higher adjacent foundations, using nonuniform distribution, bearing capacity assumptions, and resultant force location.

Use Coulomb theory for active earth pressures and Rankine theory for passive pressures in retaining wall design, since Coulomb may overestimate passive forces, with empirical equations for risk conditions.

Apply the GLOMS theory to compute active earth pressure under earthquake conditions, incorporating horizontal and vertical seismic components, their relation to gravity, and the resulting delta paey for design.

Discusses key retaining wall checks for overturning and sliding stability, soil bearing capacity, and avoiding weak soil layers to prevent settlement and cracks.

Identify the overturning point at the wall toe and evaluate moments from backfill and wall weight against active earth pressure, neglect passive pressure, and apply a safety factor of 1.5–3.

Evaluate sliding in retaining walls by comparing horizontal resisting forces from vertical load to horizontal driving forces, using soil shear strength, the angle of internal friction, cohesion, and bearing capacity.

Calculate active earth pressure on a 3.5 m retaining wall using Kolob theory, assess bearing capacity below the foundation, and analyze horizontal and vertical forces for sliding and overturning stability.

Calculate passive earth pressure using ranking theory and Renkin equations, compare with column theory, and show how ranking theory avoids overestimating passive pressure for stable retaining walls.

Compute vertical loads for a retaining wall, including wall and base weight, backfill and cover soils, then perform overturning and sliding stability checks using passive pressure and friction.

Calculate bearing pressure for a retaining wall by balancing vertical and horizontal forces, determining overturning moment and eccentricity, then assess foundation stresses against bearing capacity to confirm safety.

Design reinforcement for the stem, toe, and heel of a retaining wall by calculating soil pressures and load combinations. Assess the section capacity and shear/bending to ensure safe performance.

Compute active earth pressure, water pressure, and surcharge for a retaining wall under seismic and groundwater effects to evaluate stability against sliding and to guide stem and toe design.

Calculate seismic loads on a retaining wall by deriving strip load forces, angles, and resultant pressures, then adjust trapezoidal distribution to match the resultant location.

This lecture guides stability checks for a retaining wall by calculating overturning and resisting moments from dead load, water pressure, and seismic forces, then assessing the factor of safety.