USCS Soil Classification

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Description

This set of functions classifies soil using the Unified Soil Classification System (USCS).

Usage

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USCS(pg = NA, ps = NA, pf = NA, Cc = NA, Cu = NA,
     LL = NA, PL = NA, PI = NA, sieve = NA, size = NA,
     percent = NA, metric = NA)
USCS.fine.symbol(LL, PL, PI = NA)
USCS.coarse.symbol(pg, ps, pf, Cc, Cu, PI = NA, LL, PL)

Arguments

pg

percent gravel

ps

percent sand

pf

percent fines

Cu

coefficient of uniformity

Cc

coefficient of curvature

sieve

vector of sieve numbers (according to ASTM D422) in grain-size distribution

size

vector of grain sizes (in or mm) in distribution

percent

vector of percent passing in grain-size distribution

metric

logical variable for grain-size distribution: TRUE for metric units (mm), FALSE for English units (in); only required if "size" is supplied

LL

liquid limit (percent)

PL

plastic limit (percent)

PI

plasticity index (percent)

Details

The USCS function is the master function for performing soil classifications:

  • Data on the soil's grain-size distribution are required if the percent fines is less than or equal to 12 percent. The user has three options for input to this function:

    1. Sieve numbers (sieve); and percent passing

    2. Grain sizes (size); and percent passing

    3. Percent components (pg, ps, pf) and coefficients of uniformity and curvature (Cc and Cu)

  • Data on the soil's fines [either (a) LL and PL or (b) LL and PI] are required if the percent fines is greater than or equal to 5 percent.

  • If percent components are specified, then Cu and Cc are needed if pf < 85 percent.

The USCS.fine.symbol and USCS.coarse.symbol are used to obtain the group symbols for fine-grained and coarse-grained soils, respectively. For USCS.fine.symbol, either PI or PL must be specified in addition to LL. For USCS.coarse.symbol:

  • Data on the soil's gradation (Cu and Cc) are required if the percent fines is less than or equal to 12 percent.

  • Data on the soil's fines [either (a) LL and PL or (b) LL and PI] are required if the percent fines is greater than or equal to 5 percent.

Value

  • USCS outputs a two-element list providing a soil's USCS group symbol and name:

    1. symbol = USCS group symbol

    2. name = USCS group name

  • USCS.fine.symbol outputs a fine-grained soil's two-letter group symbol.

  • USCS.coarse.sybmol outputs a coarse-grained soil's two-letter group symbol.

Author(s)

James Kaklamanos <kaklamanosj@merrimack.edu> and Kyle Elmy <ElmyK@merrimack.edu>

References

ASTM (2010). "Annual Book of ASTM Standards", Volume 04.08 – Soil and Rock, ASTM International, Philadelphia.

See Also

AASHTO, grainSize, Plasticity

Examples

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## Example code for USCS
USCS(pg = 15, ps = 34, pf = 51, Cc = 1, Cu = 4, LL = 40, PL = 10)