1610.1 General.
BC § 1610.1
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. Exception: Foundation walls extending not more than 8 feet (2438.4 mm) below grade and laterally supported at the top by flexible diaphragms shall be permitted to be designed for active pressure. Table 1610.1Lateral Soil Load Description of Backfill Material cUnified Soil ClassificationDesign Lateral Soil Load a(pound per square foot per foot of depth)Active pressureAt-rest pressureDescription of Backfill Material cUnified Soil ClassificationDesign Lateral Soil Load a(pound per square foot per foot of depth)Active pressureAt-rest pressureWell-graded, clean gravels; gravel-sand mixesGW3060Poorly graded clean gravels; gravel-sand mixesGP3060Silty gravels, poorly graded gravel-sand mixesGM4060Clayey gravels, poorly graded gravel-and-clay mixesGC4560Well-graded, clean sands; gravelly sand mixesSW3060Poorly graded clean sands; sand-gravel mixesSP3060Silty sands, poorly graded sand-silt mixesSM4560Sand-silt clay mix with plastic finesSM-SC45100Clayey sands, poorly graded sand-clay mixesSC60100Inorganic silts and clayey siltsML45100Mixture of inorganic silt and clayML-CL60100Inorganic clays of low to medium plasticityCL60100Organic silts and silt clays, low plasticityOLNote bNote bInorganic clayey silts, elastic siltsMHNote bNote bInorganic clays of high plasticityCHNote bNote bOrganic clays and silty claysOHNote bNote b For SI: 1 pound per square foot per foot of depth = 0.157 kPa/m, 1 foot = 304.8 mm. a. 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. b. Unsuitable as backfill material. c. The definition and classification of soil materials shall be in accordance with ASTM D 2487.
