soilDeformation {soilphysics}

Soil deformation by O'Sullivan and Robertson (1996)

Description

It calculates bulk density variation as a function of the applied mean normal stress using critical state theory, by O'Sullivan and Robertson (1996).

Usage

soilDeformation(stress, p.density, iBD, N, CI, k, k2, m, graph = FALSE, ...)

Arguments

stress

a numeric vector containing the values of mean normal stress, kPa; Note that stress can also be a vector of length 1.

p.density

a numeric vector containing the values of particle density to each stress, Mg m^{-3}.

iBD

a numeric vector containing the values of initial bulk density to each stress, Mg m^{-3}.

N

the specific volume at p = 1 kPa, to each stress

CI

the compression index, to each stress; check details

k

the recompression index, to each stress; check details

k2

the slope of the steeper recompression line to each stress (similar to the k' in O'Sullivan and Robertson (1996) model); check details

m

the value that separates yield line and VCL to each stress; check details

graph

logical; shall soilDeformation plot the graph model (only the first parameters set is ploted)?

...

further graphical arguments. See par.

Details

The specific volume (v) is given as v=PD/BD, where PD is particle density and BD is the bulk density. Please, check each parameter from O'Sullivan and Robertson (1996) model in the figure below.

Value

A list of

iBD

initial bulk density, Mg m^{-3}

fBD

final bulk density, Mg m^{-3}

vi

initial specific volume

vf

final specific volume

I

variation of soil bulk density (\%) after the applied stress

Author(s)

Renato Paiva de Lima <[e-mail]>

Anderson Rodrigo da Silva <[e-mail]>

Alvaro Pires da Silva <[e-mail]>

References

O'Sullivan, M.F.; Robertson, E.A.G. 1996. Critical state parameters from intact samples of two agricultural soils. Soil and Tillage Research, 39:161-173.

Keller, T.; Defossez, P.; Weisskopf, P.; Arvidsson, J.; Richard, G. 2007. SoilFlex: a model for prediction of soil stresses and soil compaction due to agricultural field traffic including a synthesis of analytical approaches. Soil and Tillage Research, 93:391-411.

Examples

# EXAMPLE 1
soilDeformation(stress = 300,
                p.density = 2.67,
	        iBD = 1.55,
                N = 1.9392,
                CI = 0.06037,
                k = 0.00608,
                k2 = 0.01916,
                m = 1.3,graph=TRUE,ylim=c(1.4,1.8))

# EXEMPLE 2 (combining it with soil stress)
stress <- stressTraffic(inflation.pressure=200,
	        recommended.pressure=200,
	        tyre.diameter=1.8,
	        tyre.width=0.4,
	        wheel.load=4000,
	        conc.factor=c(4,5,5,5,5,5),
                layers=c(0.05,0.1,0.3,0.5,0.7,1),
	        plot.contact.area = FALSE)

stress.mean <- stress$Stress$sigma_mean
layers <- stress$Stress$Layers
n <- length(layers)

def <- soilDeformation(stress = stress.mean,
                p.density = rep(2.67, n),
	        iBD = rep(1.55,n),
                N = rep(1.9392,n),
                CI = rep(0.06037,n),
                k = rep(0.00608,n),
                k2 = rep(0.01916,n),
                m = rep(1.3,n),graph=TRUE,ylim=c(1.4,1.8))

# Graph
plot(x = 1, y = 1,
     xlim=c(1.4,1.7),ylim=c(1,0),xaxt = "n",
     ylab = "Soil Depth",xlab ="", type="l", main="")
axis(3)
mtext("Bulk Density",side=3,line=2.5)

initial.BD <- def$iBD
final.BD <- def$fBD
points(x=initial.BD, y=layers, type="l")
points(x=initial.BD, y=layers,pch=15)
points(x=final.BD, y=layers, type="l", col=2)
points(x=final.BD, y=layers,pch=15, col=2)

# End (not run)