• Finite Strain Consolidation Theory
• Graphical User Interface
• Non-Linear Compressibility and Permeability
• Two Types of Analyses
• Multiple Pond Areas
• Multiple Filling Rates
• Surcharge Loading
• Multiple Material Types
• Multiple Top and Bottom Boundary Conditions
• Graphical Output
• Initial Existing Deposit Option

FINITE STRAIN
CONSOLIDATION THEORY

FSConsol utilizes the Finite (or Large) Strain Consolidation theory as developed by Gibson, England & Hussey (Geotechnique,1967). The advantages of the Finite Strain theory over the classical infinitesimal (Terzaghi) theory are:

• The soil can undergo large deformation.
• The soil can consolidate under the its own self weight alone (essential for an accreting deposit).
• The compressibility can change with void ratio and be highly non linear.
• The permeability can change with void ratio and be highly non linear.
• Consolidation is allowed to occur as the deposit grows.

GRAPHICAL USER INTERFACE

FSConsol is written for the Windows 7 to 10 operating systems. As such, it provides the user with e asy to use custom dialogs for entering input data, including graphical representation of the input data.

To view samples of the user interface, visit the Screen Shots page.

NON-LINEAR COMPRESSIBILITY
AND PERMEABILITY

The two main material properties controlling the amount and rate of consolidation are:

• compressibility (void ratio as a function of effective stress); and
• permeability (hydraulic conductivity as a function of void ratio).

The generality of the Finite Strain Theory allows these relationships to be highly non-linear. With FSConsol these relationships can be entered either:

in terms of a power law relationship (the most common form for these relationships)
• or as data points (which allows the user to specify any relationship).

Once entered, these relationships can be viewed graphically, to confirm the correctness of the input.

ANALYSIS TYPES

FSConsol models two basic types of analyses, each available with several different options:

• Pond Analysis
• Tank Analysis

Selecting the Pond Analysis option allows the user to simulate a mine tailings pond scenario (or any other similar scenario) in which a slurry is gradually deposited into a settling pond. In this option, the user specifies the filling rates, pond areas, and boundary conditions.

The second type of problem that can be analysed is the Tank Analysis. This type of analysis is intended to simulate a problem in which a container is instaneously filled. This type of analyses is useful for back analysing laboratory settling experiments. The user can specify whether there are one or more instantaneous events for a given problem.

MULTIPLE POND AREAS

Since mine tailings ponds are seldom cylindrical, FSConsol allows the user to specify a pond area which increases with elevation. FSConsol then tracks the deposit surface to ensure that the discharge is spread out evenly over the appropriate pond area.

MULTIPLE FILLING RATES

The filling of a tailings pond seldom consists of a single filling rate. With FSConsol, a mine tailings pond can be modelled with multiple filling rates over the life of the tailings pond, including periods where no filling occurs.

SURCHARGE LOADING

Whether a pond or a tank is being modeled, FSConsol can model a surcharge added to the surface. The user has the flexibility of describing a combination of instantaneous loads or ramp loads. For a pond analysis, this feature is useful for modeling the final reclamation cover of the pond. This feature can also be used to model laboratory consolidation tests.

MULTIPLE MATERIAL TYPES

FSConsol allows the user to enter over 30 different material types. For pond analyses, the material type changes at a specified time. For tank analyses, the user can specify several thicknesses of different materials in a given column test. Dialogs allow easy transfer of material type properties from one material type to another.

BOUNDARY CONDITIONS

In addition to an impermeable bottom boundary condition, the user can specify one of a several permeable bottom boundary conditions to accurately model the hydrologic condition at the base of the problem. Two options are available for the top boundary to reflect the water level (or lack thereof) on the surface of the deposit.

GRAPHICAL OUTPUT

There are two basic types of output from FSConsol: With Time and With Depth

The data plotted with time includes:

• Height
• Average Solids Content
• Average Excess Pore Pressure Dissipation
• Flow from the bottom boundary (if permeable)

The data plotted with depth includes:

• Solids Content and Void Ratio
• Excess Pore Pressure
• Pore Pressure
• Effective Stress
• Normalized Excess Pore Pressure

The output can be viewed graphically, print previewed, and printed from within FSConsol. See the Screen Shots  page for examples of FSConsol output. The user has control over the titles, axes scale, and other graph elements. The output is also written to a text file for importing to a spreadsheet for further manipulation if desired.

In an upcoming version, the ability to track a soil particle in space and time will be added.

INITIAL EXISTING DEPOSIT OPTION

For sites with a deposit currently in place, FSConsol allows the user to enter the state of the deposit as an initial condition. That is, the initial void ratio (solids content) and pore pressure can be set to the values found in-situ. This allows the user to determine how the present deposit will consolidate from this point forward as well as how the deposit will respond to surcharge loading or loading from additional slurry."