N.Y.C. Admin. Code § BC 1610: Section BC 1610: Soil Lateral Loads

1610.1 General.

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 1610.1 Lateral Soil Load

Description of Backfill Material

c

Unified Soil Classification

Design Lateral Soil Load

a

(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

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.