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Casagrande (flow curve) liquid limit test

Source: R/Casagrande_LL.R
Casagrande_LL.Rd

Fits a linear regression of water content vs log10(blows) from a Casagrande cup liquid limit test, estimates the liquid limit (LL) at N = 25 blows, and optionally computes plasticity index (PI), liquidity index (LI), and consistency index (CI).

Usage

Casagrande_LL(N, W, pl = NULL, w = NULL, lang = "en")

Arguments

N

numeric vector. Number of blows recorded for each trial.

W

numeric vector. Water content (percent) corresponding to each value in N.

pl

numeric or NULL. Plastic limit (percent) of the soil. If provided, plasticity index (PI) is computed. Default NULL.

w

numeric or NULL. Natural water content (percent) of the soil. Required together with pl to compute liquidity index (LI) and consistency index (CI). Default NULL.

lang

character. Label language; 'es' for Spanish or 'en' for English. Default 'en'.

Value

A named list containing a ggplot2 object (plot) with the flow curve and dashed reference lines, plus numeric scalars for the computed Atterberg indices as described in Details.

Details

The function fits a model and predicts the liquid limit as the water content at N = 25.

Returned list contents depend on which optional arguments are supplied:

  • pl = NULL, w = NULL: plot, ll.

  • pl supplied, w = NULL: plot, ll, pl, pi.

  • Both pl and w supplied: plot, ll, pl, pi, li, ci.

References

Holtz, R. D., Kovacs, W. D. & Sheahan, T. C. (2011). An Introduction to Geotechnical Engineering. Prentice Hall.

See also

Other soil mechanics: DS_plot(), Mohr_Circle(), bearing_capacity(), compaction_test(), fallcone_limits(), induced_stress(), insitu_stress(), particle_size_graph()

Examples

# Liquid limit only
Casagrande_LL(N = c(15, 20, 28, 35), W = c(42, 38, 34, 31))
#> $plot
#> Warning: log-10 transformation introduced infinite values.
#> `geom_smooth()` using formula = 'y ~ x'

#> 
#> $ll
#> [1] 35.34
#> 

# With plastic limit
Casagrande_LL(N = c(15, 20, 28, 35), W = c(42, 38, 34, 31), pl = 22, lang = 'es')
#> $plot
#> Warning: log-10 transformation introduced infinite values.
#> `geom_smooth()` using formula = 'y ~ x'

#> 
#> $ll
#> [1] 35.34
#> 
#> $pl
#> [1] 22
#> 
#> $pi
#> [1] 13.34
#> 
#> $ei
#> [1] 13.4
#> 

# With plastic limit and natural water content
Casagrande_LL(N = c(15, 20, 28, 35), W = c(42, 38, 34, 31), pl = 22, w = 30)
#> $plot
#> Warning: log-10 transformation introduced infinite values.
#> `geom_smooth()` using formula = 'y ~ x'

#> 
#> $ll
#> [1] 35.34
#> 
#> $pl
#> [1] 22
#> 
#> $pi
#> [1] 13.34
#> 
#> $li
#> [1] 0.6
#> 
#> $ci
#> [1] 0.4
#>