Title 19 Lateral Earth Pressure.pdf ✅

K௣ = passive earth pressure coefficient 2. Earth Pressure At-Rest Vertical Effective Stress σ௢ ᇱ = γz Horizontal Effective Stress σ௛ ᇱ = K௢γz For coarse-grained soils: K௢ = 1 − sinφ ᇱ Where: φ′ = drained friction angle For a dense, compacted sand backfill, K௢ = (1 − sinφ) + ቈ γௗ γௗ(୫୧୬) − 1቉ 5.5 Where: γௗ = actual compacted dry unit weight of the sand behind the wall γௗ(௠௜௡) = dry unit weight of the sand in the loosest state For overconsolidated soils ranging from clay to gravel, K௢ = (1 − sinφ ᇱ)(OCR) ୱ୧୬ థᇲ Where: OCR = Overconsolidation ratio For overconsolidated clays, K௢(௢௩௘௥௖௢௡௦௢௟௜ௗ௔௧௘ௗ) = K௢(௡௢௥௠௔௟௟௬ ௖௢௡௦௢௟௜ௗ௔௧௘ௗ)√OCR For soils at rest, the total force per unit length of the wall, P௢, is equal to the area of the pressure diagram, P௢ = 1 2 K௢γHଶ
Figure 4. Distribution of lateral earth pressure at-rest on a wall 3. Earth Pressure At-Rest for Partially Submerged Soil Figure 5. Distribution of earth pressure at rest for partially submerged soil For z ≤ Hଵ, σ௛ ᇱ = K௢γz For z ≥ Hଵ, σ௢ ᇱ = γHଵ + γ ᇱ(z − Hଵ ) Where: γ ᇱ = γ௦௔௧ − γ௪ = effective unit weight of soil The lateral pressure from pore water is u = γ௪(z − Hଵ ) Hence, the total lateral pressure from earth and water at any depth z ≥ Hଵ is equal to σ௛ = σ௛ ᇱ + u