Foundation walls and retaining walls shall be designed to resist lateral soil loads. Soil loads specified in Table 1610.1 shall be used as the minimum design lateral soil loads unless determined otherwise by a geotechnical investigation in accordance with Section 1803. Foundation walls and other walls in which horizontal movement is restricted at the top shall be designed for at-rest pressure. Retaining walls free to move and rotate at the top shall be permitted to be designed for active pressure. Design lateral pressure from surcharge loads shall be added to the lateral earth pressure load. Design lateral pressure shall be increased if soils at the site are expansive. Foundation walls shall be designed to support the weight of the full hydrostatic pressure of undrained backfill unless a drainage system is installed in accordance with Sections 1805.4.2 and 1805.4.3.
LATERAL SOIL LOAD
|DESCRIPTION OF BACKFILL MATERIALc||UNIFIED SOIL |
|DESIGN LATERAL SOIL LOADa |
(pound per square foot per foot of depth)
|Active pressure||At-rest pressure|
|Well-graded, clean gravels; gravel-sand mixes||GW||30||60|
|Poorly graded clean gravels; gravel-sand mixes||GP||30||60|
|Silty gravels, poorly graded gravel-sand mixes||GM||40||60|
|Clayey gravels, poorly graded gravel-and-clay mixes||GC||45||60|
|Well-graded, clean sands; gravelly sand mixes||SW||30||60|
|Poorly graded clean sands; sand-gravel mixes||SP||30||60|
|Silty sands, poorly graded sand-silt mixes||SM||45||60|
|Sand-silt clay mix with plastic fines||SM-SC||45||100|
|Clayey sands, poorly graded sand-clay mixes||SC||60||100|
|Inorganic silts and clayey silts||ML||45||100|
|Mixture of inorganic silt and clay||ML-CL||60||100|
|Inorganic clays of low to medium plasticity||CL||60||100|
|Organic silts and silt clays, low plasticity||OL||Note b||Note b|
|Inorganic clayey silts, elastic silts||MH||Note b||Note b|
|Inorganic clays of high plasticity||CH||Note b||Note b|
|Organic clays and silty clays||OH||Note b||Note b|
- Design lateral soil loads are given for moist conditions for the specified soils at their optimum densities. Actual field conditions shall govern. Submerged or saturated soil pressures shall include the weight of the buoyant soil plus the hydrostatic loads.
- Unsuitable as backfill material.
- The definition and classification of soil materials shall be in accordance with ASTM D 2487.