ipyconsol

ipyconsol is a nonlinear implicit finite difference solver for one-dimensional consolidation of compressible soil with secondary compression. ipyconsol is the Python version of the Javascript package iConsol.js published by Brandenberg (2017). This code is an extension of Brandenberg (2017) because it the soil can be non-uniform and the loading can vary in time. For spatially variable soil, material constants are entered as arrays, where the array length is equal to the number of nodes. For time-varying loading, a loadfactor array is specified and has a length equal to the time array.

Brandenberg, S. J. (2017) “iConsol. js: JavaScript implicit finite-difference code for nonlinear consolidation and secondary compression.” International Journal of Geomechanics, 17(6)

Installation

pip install ucla_geotech_tools

Requirements

numpy >= 1.22
C compiler (e.g., gcc, Visual Studio Build Tools)

Functions

compute(**kwargs)
get_initial(depth,Cc,Cr,sigvref,esigvref,Gs,kref,ekref,Ck,Ca,tref,qo,dsigv,ocrvoidratiotype,ocrvoidratio,ru,time,loadfactor,gammaw,tol,pa,drainagetype)
get_inputs(**kwargs)

Variables

There are two options for soil inputs (uniform and non-uniform) and two options for loading (constant and time-varying).

soil property options: option 1: soil is uniform (i.e., material parameters are constants) option 2: soil is non-uniform (i.e., material parameters are arrays, with array lengths equal to number of nodes)

load stage options: option A: constant load applied at time=0 option B: time-varying load

The options may be combined in any manner (e.g., [option 1, option A], [option 1, option B], [option 2, option A], [option 2, option B]) Uniform soil has constant model coefficients, and either void ratio, OCR, or maximum past pressure is constant.

Keyword Args:

parameter	type	description	required	default
N	int	number of elements	required for option 1
H	float	thickness of soil layer	required for option 1
depth	numpy array, dtype = float	array of depth values	required for option 2
Ntime	float	number of time steps	required for option A
tmax	float	maximum time value	required for option A
time	numpy array, dtype = float	array of time values	required for option B
loadfactor	numpy array, dtype = float	array of load factor values where stress increment = loadfactor*dsigv	required for option B
Cc	float or numpy array	virgin compression index	required
Cr	float or numpy array	recompression index	required
sigvref	float or numpy array	vertical effective stress for a point on the normal consolidation line	required
esigvref	float or numpy array	void ratio for point on normal consolidation line corresponding to esigvref	required
Gs	float or numpy array	specific gravity of solids	required
kref	float or numpy array	hydraulic conductivity for a point on the e-logk line	required
ekref	float or numpy array	void ratio for point on the e-logk like corresponding to kref
Ck	float or numpy array	coefficient of permeability variation defined as slope of e-logk relationship de/dlogk	required
Ca	float or numpy array	coefficient of secondary compression	required
tref	float or numpy array	time associated with normal consolidation line following Bjerrum’s time-line concept	required
qo	float	initial vertical effective stress at top of soil	required
dsigv	float or numpy array	change in total stress	required
ocrvoidratiotype	float or numpy array	0 OCR, 1 eo, 2 maximum past pressure	required
ocrvoidratio	float or numpy array	value of OCR, eo, or maximum past pressure, depending on value of ocrvoidratiotype	required
gammaw	float	unit weight of water		9.81
tol	float	convergence tolerance		1.0e-8
pa	float	atmospheric pressure		101.325
drainagetype	float	0 = double-drained, 1 = single-drained through top, 2 = single-drained through bottom		0

Example Commands

The example command below is for a uniform soil layer and constant loading. For other examples, see the test_ipyconsol.py file in the GitHub repository.

import ucla_geotech_tools.ipyconsol as pcl

output = pcl.compute(
    Cc=5.729,
    Cr=0.532,
    sigvref=50.0,
    esigvref=8.763,
    Gs=1.686,
    kref=1.0e-7,
    ekref=8.344,
    Ck=200.0,
    Ca=0.0,
    tref=3070.0,
    qo=10.0,
    dsigv=400.0,
    ocrvoidratiotype=0,
    ocrvoidratio=1.5,
    drainagetype=0,
    ru=0.0,
    pa=101.325,
    tol=1.0e-8,
    N=100,
    H=4.35,
    Ntime=500,
    tmax=35532000.0
)