# USCS: USCS Soil Classification In geotech: Geotechnical Engineering

## Description

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

## Usage

 ```1 2 3 4 5``` ```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 <[email protected]> and Kyle Elmy <[email protected]>

## References

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

## See Also

`AASHTO`, `grainSize`, `Plasticity`

## Examples

 ```1 2``` ```## Example code for USCS USCS(pg = 15, ps = 34, pf = 51, Cc = 1, Cu = 4, LL = 40, PL = 10) ```

geotech documentation built on May 29, 2017, 11:52 a.m.