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SSP_SRS.tex
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SSP_SRS.tex
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\documentclass[12pt]{article}
\usepackage{fontspec}
\usepackage{fullpage}
\usepackage{hyperref}
\hypersetup{bookmarks=true,colorlinks=true,linkcolor=red,citecolor=blue,filecolor=magenta,urlcolor=cyan}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{mathtools}
\usepackage{unicode-math}
\usepackage{tabularray}
\usepackage{tabularx}
\usepackage{booktabs}
\usepackage{caption}
\usepackage{graphics}
\usepackage{svg}
\usepackage{enumitem}
\usepackage{filecontents}
\usepackage[backend=bibtex]{biblatex}
\usepackage{url}
\setmathfont{Latin Modern Math}
\newcommand{\gt}{\ensuremath >}
\newcommand{\lt}{\ensuremath <}
\newlist{symbDescription}{description}{1}
\setlist[symbDescription]{noitemsep, topsep=0pt, parsep=0pt, partopsep=0pt}
\bibliography{bibfile}
\title{Software Requirements Specification for Slope Stability analysis Program}
\author{Henry Frankis and Brooks MacLachlan}
\begin{document}
\maketitle
\tableofcontents
\newpage
\section{Reference Material}
\label{Sec:RefMat}
This section records information for easy reference.
\subsection{Table of Units}
\label{Sec:ToU}
The unit system used throughout is SI (Système International d'Unités). In addition to the basic units, several derived units are also used. For each unit, the \hyperref[Table:ToU]{Table of Units} lists the symbol, a description, and the SI name.
\begin{longtblr}
[caption={Table of Units}]
{colspec={l l l}, rowhead=1, hline{1,Z}=\heavyrulewidth, hline{2}=\lightrulewidth}
\textbf{Symbol} & \textbf{Description} & \textbf{SI Name}
\\
${{}^{\circ}}$ & angle & degree
\\
${\text{kg}}$ & mass & kilogram
\\
${\text{m}}$ & length & metre
\\
${\text{N}}$ & force & newton
\\
${\text{Pa}}$ & pressure & pascal
\\
${\text{s}}$ & time & second
\label{Table:ToU}
\end{longtblr}
\subsection{Table of Symbols}
\label{Sec:ToS}
The symbols used in this document are summarized in the \hyperref[Table:ToS]{Table of Symbols} along with their units. Throughout the document, a subscript $i$ indicates that the value will be taken at, and analyzed at, a slice or slice interface composing the total slip mass. For vector quantities, the units shown are for each component of the vector.
\begin{longtblr}
[caption={Table of Symbols}]
{colspec={l X[l] l}, rowhead=1, hline{1,Z}=\heavyrulewidth, hline{2}=\lightrulewidth}
\textbf{Symbol} & \textbf{Description} & \textbf{Units}
\\
$A$ & Area: A part of an object or surface. & ${\text{m}^{2}}$
\\
$\symbf{a}\text{(}t\text{)}$ & Acceleration: The rate of change of a body's velocity. & $\frac{\text{m}}{\text{s}^{2}}$
\\
$\symbf{b}$ & Base Width of Slices: The width of each slice in the $x$-direction. & ${\text{m}}$
\\
${\symbf{C}_{\text{den}}}$ & Proportionality Constant Denominator: Values for each slice that sum together to form the denominator of the interslice normal to shear force proportionality constant. & ${\text{N}}$
\\
${\symbf{C}_{\text{num}}}$ & Proportionality Constant Numerator: Values for each slice that sum together to form the numerator of the interslice normal to shear force proportionality constant. & ${\text{N}}$
\\
$c'$ & Effective Cohesion: The internal pressure that sticks particles of soil together. & ${\text{Pa}}$
\\
$\mathit{const\_f}$ & Decision on F: A Boolean decision on which form of f the user desires: constant if true, or half-sine if false. & --
\\
${F_{\text{n}}}$ & Total Normal Force: Component of a force in the normal direction. & ${\text{N}}$
\\
${F_{\text{rot}}}$ & Force Causing Rotation: A force in the direction of rotation. & ${\text{N}}$
\\
${F_{\text{S}}}$ & Factor of Safety: The global stability metric of a slip surface of a slope, defined as the ratio of resistive shear force to mobilized shear force. & --
\\
${F_{\text{t}}}$ & Tangential Force: Component of a force in the tangential direction. & ${\text{N}}$
\\
${F_{\text{x}}}$ & $x$-coordinate of the Force: The force acting in the $x$-direction. & ${\text{N}}$
\\
${F_{\text{y}}}$ & $y$-coordinate of the Force: The force acting in the $y$-direction. & ${\text{N}}$
\\
$\symbf{F}$ & Force: An interaction that tends to produce change in the motion of an object. & ${\text{N}}$
\\
${{\symbf{F}_{\text{x}}}^{\text{G}}}$ & Sums of the Interslice Normal Forces: The sums of the normal forces acting on each pair of adjacent interslice boundaries. & ${\text{N}}$
\\
${{\symbf{F}_{\text{x}}}^{\text{H}}}$ & Sums of the Interslice Normal Water Forces: The sums of the normal water forces acting on each pair of adjacent interslice boundaries. & ${\text{N}}$
\\
$\symbf{f}$ & Interslice Normal to Shear Force Ratio Variation Function: A function of distance in the $x$-direction that describes the variation of the interslice normal to shear ratio. & --
\\
$\symbf{G}$ & Interslice Normal Forces: The forces per meter in the $z$-direction exerted between each pair of adjacent slices. & $\frac{\text{N}}{\text{m}}$
\\
$\symbf{g}$ & Gravitational Acceleration: The approximate acceleration due to gravity on Earth at sea level. & $\frac{\text{m}}{\text{s}^{2}}$
\\
$\symbf{H}$ & Interslice Normal Water Forces: The normal water forces per meter in the $z$-direction exerted in the $x$-direction between each pair of adjacent slices. & $\frac{\text{N}}{\text{m}}$
\\
$h$ & Height: The distance above a reference point for a point of interest. & ${\text{m}}$
\\
$\symbf{h}$ & $y$-direction Heights of Slices: The heights in the $y$-direction from the base of each slice to the slope surface, at the $x$-direction midpoint of the slice. & ${\text{m}}$
\\
${\symbf{h}^{\text{L}}}$ & Heights of the Left Side of Slices: The heights of the left side of each slice, assuming slice surfaces have negative slope. & ${\text{m}}$
\\
${\symbf{h}^{\text{R}}}$ & Heights of the Right Side of Slices: The heights of the right side of each slice, assuming slice surfaces have negative slope. & ${\text{m}}$
\\
${\symbf{h}_{\text{z}}}$ & Heights of Interslice Normal Forces: The heights in the $y$-direction of the interslice normal forces on each slice. & ${\text{m}}$
\\
${\symbf{h}_{\text{z,w}}}$ & Heights of the Water Table: The heights in the $y$-direction from the base of each slice to the water table. & ${\text{m}}$
\\
$i$ & Index: A number representing a single slice. & --
\\
$\symbf{\hat{j}}$ & Unit Vector: A vector that has a magnitude of one. & --
\\
${K_{\text{c}}}$ & Seismic Coefficient: The proportionality factor of force that weight pushes outwards; caused by seismic earth movements. & --
\\
${\symbf{L}_{b}}$ & Total Base Lengths of Slices: The lengths of each slice in the direction parallel to the slope of the base. & ${\text{m}}$
\\
${\symbf{L}_{s}}$ & Surface Lengths of Slices: The lengths of each slice in the direction parallel to the slope of the surface. & ${\text{m}}$
\\
$M$ & Moment: A measure of the tendency of a body to rotate about a specific point or axis. & $\text{N}\text{m}$
\\
$m$ & Mass: The quantity of matter in a body. & ${\text{kg}}$
\\
$\symbf{N}$ & Normal Forces: The total reactive forces per meter in the $z$-direction for each slice of a soil surface subject to a body resting on it. & $\frac{\text{N}}{\text{m}}$
\\
$\symbf{N'}$ & Effective Normal Forces: The forces per meter in the $z$-direction for each slice of a soil surface, subtracting pore water reactive force from total reactive force. & $\frac{\text{N}}{\text{m}}$
\\
$n$ & Number of Slices: The number of slices into which the slip surface is divided. & --
\\
$P$ & Resistive Shear Force: The Mohr Coulomb frictional force that describes the limit of mobilized shear force that can be withstood before failure. & ${\text{N}}$
\\
$\symbf{P}$ & Resistive Shear Forces: The Mohr Coulomb frictional forces per meter in the $z$-direction for each slice that describe the limit of mobilized shear force the slice can withstand before failure. & $\frac{\text{N}}{\text{m}}$
\\
$p$ & Pressure: A force exerted over an area. & ${\text{Pa}}$
\\
$\symbf{Q}$ & External Forces: The forces per meter in the $z$-direction acting into the surface from the midpoint of each slice. & $\frac{\text{N}}{\text{m}}$
\\
$\symbf{R}$ & Resistive Shear Forces Without the Influence of Interslice Forces: The resistive shear forces per meter without the influence of interslice forces in the $z$-direction for each slice. & $\frac{\text{N}}{\text{m}}$
\\
$r$ & Length of the Moment Arm: The distance between a force causing rotation and the axis of rotation. & ${\text{m}}$
\\
$\symbf{r}$ & Position Vector: A vector from the origin of the Cartesian coordinate system defined to the point where the force is applied. & ${\text{m}}$
\\
$S$ & Mobilized Shear Force: The shear force in the direction of potential motion. & ${\text{N}}$
\\
$\symbf{S}$ & Mobilized Shear Force: The mobilized shear force per meter in the $z$-direction for each slice. & $\frac{\text{N}}{\text{m}}$
\\
$\symbf{T}$ & Mobilized Shear Forces Without the Influence of Interslice Forces: The mobilized shear forces per meter without the influence of interslice forces in the $z$-direction for each slice. & $\frac{\text{N}}{\text{m}}$
\\
${\symbf{U}_{\text{b}}}$ & Base Hydrostatic Forces: The forces per meter in the $z$-direction from water pressure within each slice. & $\frac{\text{N}}{\text{m}}$
\\
${\symbf{U}_{\text{g}}}$ & Surface Hydrostatic Forces: The forces per meter in the $z$-direction from water pressure acting into each slice from standing water on the slope surface. & $\frac{\text{N}}{\text{m}}$
\\
$u$ & Pore Pressure: The pressure that comes from water within the soil. & ${\text{Pa}}$
\\
$\symbf{u}$ & Displacement: The change in an object's location relative to a reference point. & ${\text{m}}$
\\
$V$ & Volume: The amount of space that a substance or object occupies. & ${\text{m}^{3}}$
\\
${\symbf{V}_{\text{dry}}}$ & Volumes of Dry Soil: The amount of space occupied by dry soil for each slice. & ${\text{m}^{3}}$
\\
${\symbf{V}_{\text{sat}}}$ & Volumes of Saturated Soil: The amount of space occupied by saturated soil for each slice. & ${\text{m}^{3}}$
\\
$v$ & Local Index: Used as a bound variable index in calculations. & --
\\
$W$ & Weight: The gravitational force acting on an object. & ${\text{N}}$
\\
$\symbf{W}$ & Weights: The downward force per meter in the $z$-direction on each slice caused by gravity. & $\frac{\text{N}}{\text{m}}$
\\
$\symbf{X}$ & Interslice Shear Forces: The shear forces per meter in the $z$-direction exerted between adjacent slices. & $\frac{\text{N}}{\text{m}}$
\\
$x$ & $x$-coordinate: The $x$-coordinate in the Cartesian coordinate system. & ${\text{m}}$
\\
${{x_{\text{slip}}}^{\text{maxEtr}}}$ & Maximum Entry $x$-coordinate: The maximum potential $x$-coordinate for the entry point of a slip surface. & ${\text{m}}$
\\
${{x_{\text{slip}}}^{\text{maxExt}}}$ & Maximum Exit $x$-coordinate: The maximum potential $x$-coordinate for the exit point of a slip surface. & ${\text{m}}$
\\
${{x_{\text{slip}}}^{\text{minEtr}}}$ & Minimum Entry $x$-coordinate: The minimum potential $x$-coordinate for the entry point of a slip surface. & ${\text{m}}$
\\
${{x_{\text{slip}}}^{\text{minExt}}}$ & Minimum Exit $x$-coordinate: The minimum potential $x$-coordinate for the exit point of a slip surface. & ${\text{m}}$
\\
${\symbf{x}_{\text{cs}}}\text{,}{\symbf{y}_{\text{cs}}}$ & Critical Slip Surface Coordinates: The set of $x$-coordinates and $y$-coordinates that describe the vertices of the critical slip surface. & ${\text{m}}$
\\
${\symbf{x}_{\text{slip}}}$ & $x$-coordinates of the Slip Surface: $x$-coordinates of points on the slip surface. & ${\text{m}}$
\\
${\symbf{x}_{\text{slope}}}$ & $x$-coordinates of the Slope: $x$-coordinates of points on the soil slope. & ${\text{m}}$
\\
${\symbf{x}_{\text{wt}}}$ & $x$-coordinates of the Water Table: X-positions of the water table. & ${\text{m}}$
\\
$y$ & $y$-coordinate: The $y$-coordinate in the Cartesian coordinate system. & ${\text{m}}$
\\
${{y_{\text{slip}}}^{\text{max}}}$ & Maximum $y$-coordinate: The maximum potential $y$-coordinate of a point on a slip surface. & ${\text{m}}$
\\
${{y_{\text{slip}}}^{\text{min}}}$ & Minimum $y$-coordinate: The minimum potential $y$-coordinate of a point on a slip surface. & ${\text{m}}$
\\
${\symbf{y}_{\text{slip}}}$ & $y$-coordinates of the Slip Surface: Heights of the slip surface. & ${\text{m}}$
\\
${\symbf{y}_{\text{slope}}}$ & $y$-coordinates of the Slope: $y$-coordinates of points on the soil slope. & ${\text{m}}$
\\
${\symbf{y}_{\text{wt}}}$ & $y$-coordinates of the Water Table: Heights of the water table. & ${\text{m}}$
\\
$z$ & $z$-coordinate: The $z$-coordinate in the Cartesian coordinate system. & ${\text{m}}$
\\
$\symbf{α}$ & Base Angles: The angles between the base of each slice and the horizontal. & ${{}^{\circ}}$
\\
$\symbf{β}$ & Surface Angles: The angles between the surface of each slice and the horizontal. & ${{}^{\circ}}$
\\
$γ$ & Specific Weight: The weight per unit volume. & $\frac{\text{N}}{\text{m}^{3}}$
\\
${γ_{\text{dry}}}$ & Soil Dry Unit Weight: The weight of a dry soil/ground layer divided by the volume of the layer. & $\frac{\text{N}}{\text{m}^{3}}$
\\
${γ_{\text{sat}}}$ & Soil Saturated Unit Weight: The weight of saturated soil/ground layer divided by the volume of the layer. & $\frac{\text{N}}{\text{m}^{3}}$
\\
${γ_{w}}$ & Unit Weight of Water: The weight of one cubic meter of water. & $\frac{\text{N}}{\text{m}^{3}}$
\\
$λ$ & Proportionality Constant: The ratio of the interslice normal to the interslice shear force. & --
\\
$π$ & Ratio of Circumference to Diameter for Any Circle: The ratio of a circle's circumference to its diameter. & --
\\
$ρ$ & Density: The mass per unit volume. & $\frac{\text{kg}}{\text{m}^{3}}$
\\
$σ$ & Total Normal Stress: The total force per area acting on the soil mass. & ${\text{Pa}}$
\\
$σ'$ & Effective Stress: The stress in a soil mass that is effective in causing volume changes and mobilizes the shear strength arising from friction; represents the average stress carried by the soil skeleton. & ${\text{Pa}}$
\\
${σ_{N}}'$ & Effective Normal Stress: The normal stress in a soil mass that is effective in causing volume changes; represents the average normal stress carried by the soil skeleton. & ${\text{Pa}}$
\\
$τ$ & Tangential Stress: The shear force per unit area. & ${\text{Pa}}$
\\
${τ^{\text{f}}}$ & Shear Strength: The strength of a material against shear failure. & ${\text{Pa}}$
\\
$\symbf{τ}$ & Torque: A twisting force that tends to cause rotation. & $\text{N}\text{m}$
\\
$\symbf{Φ}$ & First Function for Incorporating Interslice Forces Into Shear Force: The function for converting resistive shear without the influence of interslice forces, to a calculation considering the interslice forces. & --
\\
$φ'$ & Effective Angle of Friction: The angle of inclination with respect to the horizontal axis of the Mohr-Coulomb shear resistance line. & ${{}^{\circ}}$
\\
$\symbf{Ψ}$ & Second Function for Incorporating Interslice Forces Into Shear Force: The function for converting mobile shear without the influence of interslice forces, to a calculation considering the interslice forces. & --
\\
$\symbf{ω}$ & Imposed Load Angles: The angles between the external force acting into the surface of each slice and the vertical. & ${{}^{\circ}}$
\label{Table:ToS}
\end{longtblr}
\subsection{Abbreviations and Acronyms}
\label{Sec:TAbbAcc}
\begin{longtblr}
[caption={Abbreviations and Acronyms}]
{colspec={l l}, rowhead=1, hline{1,Z}=\heavyrulewidth, hline{2}=\lightrulewidth}
\textbf{Abbreviation} & \textbf{Full Form}
\\
2D & Two-Dimensional
\\
3D & Three-Dimensional
\\
A & Assumption
\\
DD & Data Definition
\\
GD & General Definition
\\
GS & Goal Statement
\\
IM & Instance Model
\\
LC & Likely Change
\\
PS & Physical System Description
\\
R & Requirement
\\
RefBy & Referenced by
\\
Refname & Reference Name
\\
SRS & Software Requirements Specification
\\
SSP & Slope Stability analysis Program
\\
TM & Theoretical Model
\\
UC & Unlikely Change
\\
Uncert. & Typical Uncertainty
\label{Table:TAbbAcc}
\end{longtblr}
\section{Introduction}
\label{Sec:Intro}
A slope of geological mass, composed of soil and rock and sometimes water, is subject to the influence of gravity on the mass. This can cause instability in the form of soil or rock movement. The effects of soil or rock movement can range from inconvenient to seriously hazardous, resulting in significant life and economic losses. Slope stability is of interest both when analysing natural slopes, and when designing an excavated slope. Slope stability analysis is the assessment of the safety of a slope, identifying the surface most likely to experience slip and an index of its relative stability known as the factor of safety.
The following section provides an overview of the Software Requirements Specification (SRS) for a slope stability analysis problem. The developed program will be referred to as the Slope Stability analysis Program (SSP). This section explains the purpose of this document, the scope of the requirements, the characteristics of the intended reader, and the organization of the document.
\subsection{Purpose of Document}
\label{Sec:DocPurpose}
The primary purpose of this document is to record the requirements of SSP. Goals, assumptions, theoretical models, definitions, and other model derivation information are specified, allowing the reader to fully understand and verify the purpose and scientific basis of SSP. With the exception of \hyperref[Sec:SysConstraints]{system constraints}, this SRS will remain abstract, describing what problem is being solved, but not how to solve it.
This document will be used as a starting point for subsequent development phases, including writing the design specification and the software verification and validation plan. The design document will show how the requirements are to be realized, including decisions on the numerical algorithms and programming environment. The verification and validation plan will show the steps that will be used to increase confidence in the software documentation and the implementation. Although the SRS fits in a series of documents that follow the so-called waterfall model, the actual development process is not constrained in any way. Even when the waterfall model is not followed, as Parnas and Clements point out \cite{parnasClements1986}, the most logical way to present the documentation is still to ``fake'' a rational design process.
\subsection{Scope of Requirements}
\label{Sec:ReqsScope}
The scope of the requirements includes stability analysis of a two-dimensional (2D) soil mass, composed of a single homogeneous layer with constant material properties. The soil mass is assumed to extend infinitely in the third dimension. The analysis will be at an instant in time; factors that may change the soil properties over time will not be considered.
\subsection{Characteristics of Intended Reader}
\label{Sec:ReaderChars}
Reviewers of this documentation should have an understanding of undergraduate level 4 physics and undergraduate level 2 or higher solid mechanics. It would be an asset to understand soil mechanics. The users of SSP can have a lower level of expertise, as explained in \hyperref[Sec:UserChars]{Sec:User Characteristics}.
\subsection{Organization of Document}
\label{Sec:DocOrg}
The organization of this document follows the template for an SRS for scientific computing software proposed by \cite{koothoor2013}, \cite{smithLai2005}, \cite{smithEtAl2007}, and \cite{smithKoothoor2016}. The presentation follows the standard pattern of presenting goals, theories, definitions, and assumptions. For readers that would like a more bottom up approach, they can start reading the \hyperref[Sec:IMs]{instance models} and trace back to find any additional information they require.
The \hyperref[Sec:GoalStmt]{goal statements} are refined to the theoretical models and the \hyperref[Sec:TMs]{theoretical models} to the \hyperref[Sec:IMs]{instance models}. The instance models provide the set of algebraic equations that must be solved.
\section{General System Description}
\label{Sec:GenSysDesc}
This section provides general information about the system. It identifies the interfaces between the system and its environment, describes the user characteristics, and lists the system constraints.
\subsection{System Context}
\label{Sec:SysContext}
\hyperref[Figure:sysCtxDiag]{Fig:sysCtxDiag} shows the system context. A circle represents an external entity outside the software. A rectangle represents the software system itself (SSP). Arrows are used to show the data flow between the system and its environment.
\begin{figure}
\begin{center}
\includegraphics[width=\textwidth]{../../../../datafiles/ssp/SystemContextFigure.png}
\caption{System Context}
\label{Figure:sysCtxDiag}
\end{center}
\end{figure}
The responsibilities of the user and the system are as follows:
\begin{itemize}
\item{User Responsibilities}
\begin{itemize}
\item{Provide the input data related to the soil layer(s) and water table (if applicable), ensuring conformation to input data format required by SSP}
\item{Ensure that consistent units are used for input variables}
\item{Ensure required \hyperref[Sec:Assumps]{software assumptions} are appropriate for the problem to which the user is applying the software}
\end{itemize}
\item{SSP Responsibilities}
\begin{itemize}
\item{Detect data type mismatch, such as a string of characters input instead of a floating point number}
\item{Verify that the inputs satisfy the required physical and other \hyperref[Sec:DataConstraints]{data constraints}}
\item{Identify the critical slip surface within the possible input range}
\item{Find the factor of safety for the slope}
\item{Find the interslice normal force and shear force along the critical slip surface}
\end{itemize}
\end{itemize}
\subsection{User Characteristics}
\label{Sec:UserChars}
The end user of SSP should have an understanding of undergraduate Level 1 Calculus and Physics, and be familiar with soil and material properties, specifically effective cohesion, effective angle of friction, and unit weight.
\subsection{System Constraints}
\label{Sec:SysConstraints}
The Morgenstern-Price method \cite{morgenstern1965}, which involves dividing the slope into vertical slices, will be used to derive the equations for analysing the slope.
\section{Specific System Description}
\label{Sec:SpecSystDesc}
This section first presents the problem description, which gives a high-level view of the problem to be solved. This is followed by the solution characteristics specification, which presents the assumptions, theories, and definitions that are used.
\subsection{Problem Description}
\label{Sec:ProbDesc}
A system is needed to evaluate the factor of safety of a slope's slip surface and identify the critical slip surface of the slope, as well as the interslice normal force and shear force along the critical slip surface.
\subsubsection{Terminology and Definitions}
\label{Sec:TermDefs}
This subsection provides a list of terms that are used in the subsequent sections and their meaning, with the purpose of reducing ambiguity and making it easier to correctly understand the requirements.
\begin{itemize}
\item{Factor of safety: The global stability metric of a slip surface of a slope, defined as the ratio of resistive shear force to mobilized shear force.}
\item{Slip surface: A surface within a slope that has the potential to fail or displace due to load or other forces.}
\item{Critical slip surface: Slip surface of the slope that has the lowest factor of safety, and is therefore most likely to experience failure.}
\item{Water table: The upper boundary of a saturated zone in the ground.}
\item{Stress: The ratio of an applied force to a cross-sectional area.}
\item{Strain: A measure of deformation representing the displacement between particles in the body relative to a reference length.}
\item{Normal force: A force applied perpendicular to the plane of the material.}
\item{Shear force: A force applied parallel to the plane of the material.}
\item{Mobilized shear force: The shear force in the direction of potential motion, thus encouraging motion along the plane.}
\item{Resistive shear force: The shear force in the direction opposite to the direction of potential motion, thus hindering motion along the plane.}
\item{Effective forces and stresses: The normal force or normal stress carried by the soil skeleton, composed of the effective force or stress and the force or stress exerted by water.}
\item{Cohesion: An attractive force between adjacent particles that holds the matter together.}
\item{Isotropy: A condition where the value of a property is independent of the direction in which it is measured.}
\item{Plane strain: A condition where the resultant stresses in one of the directions of a three-dimensional material can be approximated as zero. This condition results when a body is constrained to not deform in one direction, or when the length of one dimension of the body dominates the others, to the point where it can be assumed as infinite. Stresses in the direction of the dominant dimension can be approximated as zero.}
\end{itemize}
\subsubsection{Physical System Description}
\label{Sec:PhysSyst}
The physical system of SSP, as shown in \hyperref[Figure:PhysicalSystem]{Fig:PhysicalSystem}, includes the following elements:
\begin{itemize}
\item[PS1:]{A slope comprised of one soil layer.}
\item[PS2:]{A water table, which may or may not exist.}
\end{itemize}
\begin{figure}
\begin{center}
\includegraphics[width=\textwidth]{../../../../datafiles/ssp/PhysSyst.png}
\caption{An example slope for analysis by SSP, where the dashed line represents the water table}
\label{Figure:PhysicalSystem}
\end{center}
\end{figure}
Morgenstern-Price analysis \cite{morgenstern1965} of the slope involves representing the slope as a series of vertical slices. As shown in \hyperref[Figure:IndexConvention]{Fig:IndexConvention}, the index $i$ is used to denote a value for a single slice, and an interslice value at a given index $i$ refers to the value between slice $i$ and adjacent slice $i+1$.
\begin{figure}
\begin{center}
\includegraphics[width=\textwidth]{../../../../datafiles/ssp/IndexConvention.png}
\caption{Index convention for slice and interslice values}
\label{Figure:IndexConvention}
\end{center}
\end{figure}
A free body diagram of the forces acting on a slice is displayed in \hyperref[Figure:ForceDiagram]{Fig:ForceDiagram}. The specific forces and symbols will be discussed in detail in \hyperref[Sec:GDs]{Sec:General Definitions} and \hyperref[Sec:DDs]{Sec:Data Definitions}.
\begin{figure}
\begin{center}
\includegraphics[width=\textwidth]{../../../../datafiles/ssp/ForceDiagram.png}
\caption{Free body diagram of forces acting on a slice}
\label{Figure:ForceDiagram}
\end{center}
\end{figure}
\subsubsection{Goal Statements}
\label{Sec:GoalStmt}
Given the shape of the soil mass, the location of the water table, and the material properties of the soil, the goal statements are:
\begin{itemize}
\item[Identify-Crit-and-FS:\phantomsection\label{identifyCritAndFS}]{Identify the critical slip surface and the corresponding factor of safety.}
\item[Determine-Normal-Forces:\phantomsection\label{determineNormalF}]{Determine the interslice normal forces between each pair of vertical slices of the slope.}
\item[Determine-Shear-Forces:\phantomsection\label{determineShearF}]{Determine the interslice shear forces between each pair of vertical slices of the slope.}
\end{itemize}
\subsection{Solution Characteristics Specification}
\label{Sec:SolCharSpec}
The instance models that govern SSP are presented in the \hyperref[Sec:IMs]{Instance Model Section}. The information to understand the meaning of the instance models and their derivation is also presented, so that the instance models can be verified.
\subsubsection{Assumptions}
\label{Sec:Assumps}
This section simplifies the original problem and helps in developing the theoretical models by filling in the missing information for the physical system. The assumptions refine the scope by providing more detail.
\begin{itemize}
\item[Slip-Surface-Concave:\phantomsection\label{assumpSSC}]{The slip surface is concave with respect to the slope surface. The (${\symbf{x}_{\text{slip}}}$, ${\symbf{y}_{\text{slip}}}$) coordinates of a slip surface follow a concave up function. (RefBy: \hyperref[IM:crtSlpId]{IM:crtSlpId}.)}
\item[Factor-of-Safety:\phantomsection\label{assumpFOS}]{The factor of safety is assumed to be constant across the entire slip surface. (RefBy: \hyperref[GD:mobShr]{GD:mobShr}.)}
\item[Soil-Layer-Homogeneous:\phantomsection\label{assumpSLH}]{The soil mass is homogeneous, with consistent soil properties throughout. (RefBy: \hyperref[GD:sliceWght]{GD:sliceWght}, \hyperref[GD:resShr]{GD:resShr}, and \hyperref[LC_inhomogeneous]{LC:Calculate-Inhomogeneous-Soil-Layers}.)}
\item[Soil-Properties:\phantomsection\label{assumpSP}]{The soil properties are independent of dry or saturated conditions, with the exception of unit weight. (RefBy: \hyperref[GD:resShr]{GD:resShr}.)}
\item[Soil-Layers-Isotropic:\phantomsection\label{assumpSLI}]{The soil mass is treated as if the effective cohesion and effective angle of friction are isotropic properties. (RefBy: \hyperref[GD:resShr]{GD:resShr}.)}
\item[Interslice-Norm-Shear-Forces-Linear:\phantomsection\label{assumpINSFL}]{Following the assumption of Morgenstern and Price (\cite{morgenstern1965}), interslice normal forces and interslice shear forces have a proportional relationship, depending on a proportionality constant ($λ$) and a function ($\symbf{f}$) describing variation depending on $x$ position. (RefBy: \hyperref[GD:normShrR]{GD:normShrR}, \hyperref[IM:fctSfty]{IM:fctSfty}, \hyperref[IM:nrmShrFor]{IM:nrmShrFor}, and \hyperref[UC_normshearlinear]{UC:Normal-And-Shear-Linear-Only}.)}
\item[Plane-Strain-Conditions:\phantomsection\label{assumpPSC}]{The slope and slip surface extends far into and out of the geometry ($z$ coordinate). This implies plane strain conditions, making 2D analysis appropriate. (RefBy: \hyperref[GD:srfWtrF]{GD:srfWtrF}, \hyperref[GD:sliceWght]{GD:sliceWght}, \hyperref[GD:resShr]{GD:resShr}, \hyperref[GD:effNormF]{GD:effNormF}, and \hyperref[GD:baseWtrF]{GD:baseWtrF}.)}
\item[Effective-Norm-Stress-Large:\phantomsection\label{assumpENSL}]{The effective normal stress is large enough that the shear strength to effective normal stress relationship can be approximated as a linear relationship. (RefBy: \hyperref[TM:equilibrium]{TM:equilibrium} and \hyperref[UC_2donly]{UC:2D-Analysis-Only}.)}
\item[Surface-Base-Slice-between-Interslice-Straight-Lines:\phantomsection\label{assumpSBSBISL}]{The surface and base of a slice are approximated as straight lines. (RefBy: \hyperref[GD:srfWtrF]{GD:srfWtrF}, \hyperref[GD:sliceWght]{GD:sliceWght}, \hyperref[GD:baseWtrF]{GD:baseWtrF}, \hyperref[TM:mcShrStrgth]{TM:mcShrStrgth}, \hyperref[DD:slcHeight]{DD:slcHeight}, \hyperref[DD:angleB]{DD:angleB}, and \hyperref[DD:angleA]{DD:angleA}.)}
\item[Edge-Slices:\phantomsection\label{assumpES}]{The interslice forces at the 0th and $n$th interslice interfaces are zero. (RefBy: \hyperref[IM:intsliceFs]{IM:intsliceFs}, \hyperref[IM:fctSfty]{IM:fctSfty}, and \hyperref[IM:nrmShrFor]{IM:nrmShrFor}.)}
\item[Seismic-Force:\phantomsection\label{assumpSF}]{There is no seismic force acting on the slope. (RefBy: \hyperref[IM:fctSfty]{IM:fctSfty}, \hyperref[IM:nrmShrFor]{IM:nrmShrFor}, and \hyperref[LC_seismic]{LC:Calculate-Seismic-Force}.)}
\item[Surface-Load:\phantomsection\label{assumpSL}]{There is no imposed surface load, and therefore no external forces, acting on the slope. (RefBy: \hyperref[IM:fctSfty]{IM:fctSfty}, \hyperref[IM:nrmShrFor]{IM:nrmShrFor}, and \hyperref[LC_external]{LC:Calculate-External-Force}.)}
\item[Water-Intersects-Base-Edge:\phantomsection\label{assumpWIBE}]{The water table only intersects the base of a slice at an edge of the slice. (RefBy: \hyperref[GD:sliceWght]{GD:sliceWght} and \hyperref[GD:baseWtrF]{GD:baseWtrF}.)}
\item[Water-Intersects-Surface-Edge:\phantomsection\label{assumpWISE}]{The water table only intersects the slope surface at the edge of a slice. (RefBy: \hyperref[GD:srfWtrF]{GD:srfWtrF} and \hyperref[GD:sliceWght]{GD:sliceWght}.)}
\item[Negligible-Effect-Surface-Slope-Seismic:\phantomsection\label{assumpNESSS}]{The effect of the slope of the surface of the soil on the seismic force is assumed to be negligible. (RefBy: \hyperref[GD:momentEql]{GD:momentEql}.)}
\item[Hydrostatic-Force-Slice-Midpoint:\phantomsection\label{assumpHFSM}]{The resultant surface hydrostatic forces act into the midpoint of each slice surface and the resultant base hydrostatic forces act into the midpoint of each slice base. (RefBy: \hyperref[GD:srfWtrF]{GD:srfWtrF}, \hyperref[GD:momentEql]{GD:momentEql}, and \hyperref[GD:baseWtrF]{GD:baseWtrF}.)}
\end{itemize}
\subsubsection{Theoretical Models}
\label{Sec:TMs}
This section focuses on the general equations and laws that SSP is based on.
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{TM:factOfSafety}
\phantomsection
\label{TM:factOfSafety}
\\ \midrule
Label & Factor of safety
\\ \midrule
Equation & \begin{displaymath}
{F_{\text{S}}}=\frac{P}{S}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{${F_{\text{S}}}$ is the factor of safety (Unitless)}
\item{$P$ is the resistive shear force (${\text{N}}$)}
\item{$S$ is the mobilized shear force (${\text{N}}$)}
\end{symbDescription}
\\ \midrule
Source & \cite{fredlund1977}
\\ \midrule
RefBy & \hyperref[GD:mobShr]{GD:mobShr}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{TM:equilibrium}
\phantomsection
\label{TM:equilibrium}
\\ \midrule
Label & Equilibrium
\\ \midrule
Equation & \begin{displaymath}
\displaystyle\sum{{F_{\text{x}}}}=0
\end{displaymath}
\begin{displaymath}
\displaystyle\sum{{F_{\text{y}}}}=0
\end{displaymath}
\begin{displaymath}
\displaystyle\sum{M}=0
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{${F_{\text{x}}}$ is the $x$-coordinate of the force (${\text{N}}$)}
\end{symbDescription}
\begin{symbDescription}
\item{${F_{\text{y}}}$ is the $y$-coordinate of the force (${\text{N}}$)}
\end{symbDescription}
\begin{symbDescription}
\item{$M$ is the moment ($\text{N}\text{m}$)}
\end{symbDescription}
\\ \midrule
Notes & For a body in static equilibrium, the net forces and moments acting on the body will cancel out. Assuming a 2D problem (\hyperref[assumpENSL]{A:Effective-Norm-Stress-Large}), the $x$-coordinate of the force ${F_{\text{x}}}$ and $y$-coordinate of the force ${F_{\text{y}}}$ will be equal to $0$. All forces and their distance from the chosen point of rotation will create a net moment equal to $0$.
\\ \midrule
Source & \cite{fredlund1977}
\\ \midrule
RefBy & \hyperref[GD:normForcEq]{GD:normForcEq}, \hyperref[GD:momentEql]{GD:momentEql}, and \hyperref[GD:bsShrFEq]{GD:bsShrFEq}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{TM:mcShrStrgth}
\phantomsection
\label{TM:mcShrStrgth}
\\ \midrule
Label & Mohr-Coulumb shear strength
\\ \midrule
Equation & \begin{displaymath}
{τ^{\text{f}}}={σ_{N}}' \tan\left(φ'\right)+c'
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{${τ^{\text{f}}}$ is the shear strength (${\text{Pa}}$)}
\item{${σ_{N}}'$ is the effective normal stress (${\text{Pa}}$)}
\item{$φ'$ is the effective angle of friction (${{}^{\circ}}$)}
\item{$c'$ is the effective cohesion (${\text{Pa}}$)}
\end{symbDescription}
\\ \midrule
Notes & In this model the shear strength ${τ^{\text{f}}}$ is proportional to the product of the effective normal stress ${σ_{N}}'$ on the plane with its static friction in the angular form $\tan\left(φ'\right)$. The ${τ^{\text{f}}}$ versus ${σ_{N}}'$ relationship is not truly linear, but assuming the effective normal forces is strong enough, it can be approximated with a linear fit (\hyperref[assumpSBSBISL]{A:Surface-Base-Slice-between-Interslice-Straight-Lines}) where the effective cohesion $c'$ represents the ${τ^{\text{f}}}$ intercept of the fitted line.
\\ \midrule
Source & \cite{fredlund1977}
\\ \midrule
RefBy & \hyperref[GD:resShr]{GD:resShr}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{TM:effStress}
\phantomsection
\label{TM:effStress}
\\ \midrule
Label & Effective stress
\\ \midrule
Equation & \begin{displaymath}
σ'=σ-u
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$σ'$ is the effective stress (${\text{Pa}}$)}
\item{$σ$ is the total normal stress (${\text{Pa}}$)}
\item{$u$ is the pore pressure (${\text{Pa}}$)}
\end{symbDescription}
\\ \midrule
Notes & $σ$ is defined in \hyperref[DD:normStress]{DD:normStress}.
\\ \midrule
Source & \cite{fredlund1977}
\\ \midrule
RefBy & \hyperref[GD:effNormF]{GD:effNormF}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{TM:NewtonSecLawMot}
\phantomsection
\label{TM:NewtonSecLawMot}
\\ \midrule
Label & Newton's second law of motion
\\ \midrule
Equation & \begin{displaymath}
\symbf{F}=m \symbf{a}\text{(}t\text{)}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{F}$ is the force (${\text{N}}$)}
\item{$m$ is the mass (${\text{kg}}$)}
\item{$\symbf{a}\text{(}t\text{)}$ is the acceleration ($\frac{\text{m}}{\text{s}^{2}}$)}
\end{symbDescription}
\\ \midrule
Notes & The net force $\symbf{F}$ on a body is proportional to the acceleration $\symbf{a}\text{(}t\text{)}$ of the body, where $m$ denotes the mass of the body as the constant of proportionality.
\\ \midrule
Source & --
\\ \midrule
RefBy & \hyperref[GD:weight]{GD:weight}
\\ \bottomrule
\end{tabular}
\end{minipage}
\subsubsection{General Definitions}
\label{Sec:GDs}
This section collects the laws and equations that will be used to build the instance models.
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:normForcEq}
\phantomsection
\label{GD:normForcEq}
\\ \midrule
Label & Normal force equilibrium
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{N}}_{i}=\left({\symbf{W}}_{i}-{\symbf{X}}_{i-1}+{\symbf{X}}_{i}+{\symbf{U}_{\text{g},i}} \cos\left({\symbf{β}}_{i}\right)+{\symbf{Q}}_{i} \cos\left({\symbf{ω}}_{i}\right)\right) \cos\left({\symbf{α}}_{i}\right)+\left(-{K_{\text{c}}} {\symbf{W}}_{i}-{\symbf{G}}_{i}+{\symbf{G}}_{i-1}-{\symbf{H}}_{i}+{\symbf{H}}_{i-1}+{\symbf{U}_{\text{g},i}} \sin\left({\symbf{β}}_{i}\right)+{\symbf{Q}}_{i} \sin\left({\symbf{ω}}_{i}\right)\right) \sin\left({\symbf{α}}_{i}\right)
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{N}$ is the normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{W}$ is the weights ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{X}$ is the interslice shear forces ($\frac{\text{N}}{\text{m}}$)}
\item{${\symbf{U}_{\text{g}}}$ is the surface hydrostatic forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{β}$ is the surface angles (${{}^{\circ}}$)}
\item{$\symbf{Q}$ is the external forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{ω}$ is the imposed load angles (${{}^{\circ}}$)}
\item{$\symbf{α}$ is the base angles (${{}^{\circ}}$)}
\item{${K_{\text{c}}}$ is the seismic coefficient (Unitless)}
\item{$\symbf{G}$ is the interslice normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{H}$ is the interslice normal water forces ($\frac{\text{N}}{\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & This equation satisfies \hyperref[TM:equilibrium]{TM:equilibrium} in the normal direction. $\symbf{W}$ is defined in \hyperref[GD:sliceWght]{GD:sliceWght}, ${\symbf{U}_{\text{g}}}$ is defined in \hyperref[GD:srfWtrF]{GD:srfWtrF}, $\symbf{β}$ is defined in \hyperref[DD:angleB]{DD:angleB}, and $\symbf{α}$ is defined in \hyperref[DD:angleA]{DD:angleA}.
\\ \midrule
Source & \cite{chen2005}
\\ \midrule
RefBy & \hyperref[IM:fctSfty]{IM:fctSfty}
\\ \bottomrule
\end{tabular}
\end{minipage}
\paragraph{}
\label{GD:normForcEqDeriv}
Normal force equilibrium is derived from the free body diagram of \hyperref[Figure:ForceDiagram]{Fig:ForceDiagram} in \hyperref[Sec:PhysSyst]{Sec:Physical System Description}.
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:bsShrFEq}
\phantomsection
\label{GD:bsShrFEq}
\\ \midrule
Label & Base shear force equilibrium
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{S}}_{i}=\left({\symbf{W}}_{i}-{\symbf{X}}_{i-1}+{\symbf{X}}_{i}+{\symbf{U}_{\text{g},i}} \cos\left({\symbf{β}}_{i}\right)+{\symbf{Q}}_{i} \cos\left({\symbf{ω}}_{i}\right)\right) \sin\left({\symbf{α}}_{i}\right)-\left(-{K_{\text{c}}} {\symbf{W}}_{i}-{\symbf{G}}_{i}+{\symbf{G}}_{i-1}-{\symbf{H}}_{i}+{\symbf{H}}_{i-1}+{\symbf{U}_{\text{g},i}} \sin\left({\symbf{β}}_{i}\right)+{\symbf{Q}}_{i} \sin\left({\symbf{ω}}_{i}\right)\right) \cos\left({\symbf{α}}_{i}\right)
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{S}$ is the mobilized shear force ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{W}$ is the weights ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{X}$ is the interslice shear forces ($\frac{\text{N}}{\text{m}}$)}
\item{${\symbf{U}_{\text{g}}}$ is the surface hydrostatic forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{β}$ is the surface angles (${{}^{\circ}}$)}
\item{$\symbf{Q}$ is the external forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{ω}$ is the imposed load angles (${{}^{\circ}}$)}
\item{$\symbf{α}$ is the base angles (${{}^{\circ}}$)}
\item{${K_{\text{c}}}$ is the seismic coefficient (Unitless)}
\item{$\symbf{G}$ is the interslice normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{H}$ is the interslice normal water forces ($\frac{\text{N}}{\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & This equation satisfies \hyperref[TM:equilibrium]{TM:equilibrium} in the shear direction. $\symbf{W}$ is defined in \hyperref[GD:sliceWght]{GD:sliceWght}, ${\symbf{U}_{\text{g}}}$ is defined in \hyperref[GD:srfWtrF]{GD:srfWtrF}, $\symbf{β}$ is defined in \hyperref[DD:angleB]{DD:angleB}, and $\symbf{α}$ is defined in \hyperref[DD:angleA]{DD:angleA}.
\\ \midrule
Source & \cite{chen2005}
\\ \midrule
RefBy & \hyperref[IM:fctSfty]{IM:fctSfty}
\\ \bottomrule
\end{tabular}
\end{minipage}
\paragraph{}
\label{GD:bsShrFEqDeriv}
Base shear force equilibrium is derived from the free body diagram of \hyperref[Figure:ForceDiagram]{Fig:ForceDiagram} in \hyperref[Sec:PhysSyst]{Sec:Physical System Description}.
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:resShr}
\phantomsection
\label{GD:resShr}
\\ \midrule
Label & Resistive shear force
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{P}}_{i}={\symbf{N'}}_{i} \tan\left({φ'}_{i}\right)+{c'}_{i} {\symbf{L}_{b,i}}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{P}$ is the resistive shear forces ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{N'}$ is the effective normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{$φ'$ is the effective angle of friction (${{}^{\circ}}$)}
\item{$c'$ is the effective cohesion (${\text{Pa}}$)}
\item{${\symbf{L}_{b}}$ is the total base lengths of slices (${\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & ${\symbf{L}_{b}}$ is defined in \hyperref[DD:lengthLb]{DD:lengthLb}.
\\ \midrule
Source & \cite{chen2005}
\\ \midrule
RefBy & \hyperref[GD:mobShr]{GD:mobShr}
\\ \bottomrule
\end{tabular}
\end{minipage}
\paragraph{}
\label{GD:resShrDeriv}
Derived by substituting \hyperref[DD:normStress]{DD:normStress} and \hyperref[DD:tangStress]{DD:tangStress} into the Mohr-Coulomb shear strength, \hyperref[TM:mcShrStrgth]{TM:mcShrStrgth}, and multiplying both sides of the equation by the area of the slice in the shear-$z$ plane. Since the slope is assumed to extend infinitely in the $z$-direction (\hyperref[assumpPSC]{A:Plane-Strain-Conditions}), the resulting forces are expressed per metre in the $z$-direction. The effective angle of friction $φ'$ and the effective cohesion $c'$ are not indexed by $i$ because they are assumed to be isotropic (\hyperref[assumpSLI]{A:Soil-Layers-Isotropic}) and the soil is assumed to be homogeneous, with constant soil properties throughout (\hyperref[assumpSLH]{A:Soil-Layer-Homogeneous}, \hyperref[assumpSP]{A:Soil-Properties}).
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:mobShr}
\phantomsection
\label{GD:mobShr}
\\ \midrule
Label & Mobilized shear force
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{S}}_{i}=\frac{{\symbf{P}}_{i}}{{F_{\text{S}}}}=\frac{{\symbf{N'}}_{i} \tan\left({φ'}_{i}\right)+{c'}_{i} {\symbf{L}_{b,i}}}{{F_{\text{S}}}}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{S}$ is the mobilized shear force ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{P}$ is the resistive shear forces ($\frac{\text{N}}{\text{m}}$)}
\item{${F_{\text{S}}}$ is the factor of safety (Unitless)}
\item{$\symbf{N'}$ is the effective normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{$φ'$ is the effective angle of friction (${{}^{\circ}}$)}
\item{$c'$ is the effective cohesion (${\text{Pa}}$)}
\item{${\symbf{L}_{b}}$ is the total base lengths of slices (${\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & ${\symbf{L}_{b}}$ is defined in \hyperref[DD:lengthLb]{DD:lengthLb}.
\\ \midrule
Source & \cite{chen2005}
\\ \midrule
RefBy & \hyperref[IM:fctSfty]{IM:fctSfty}
\\ \bottomrule
\end{tabular}
\end{minipage}
\paragraph{}
\label{GD:mobShrDeriv}
Mobilized shear forces is derived by dividing the definition of the $\symbf{P}$ from \hyperref[GD:resShr]{GD:resShr} by the definition of the factor of safety from \hyperref[TM:factOfSafety]{TM:factOfSafety}. The factor of safety ${F_{\text{S}}}$ is not indexed by $i$ because it is assumed to be constant for the entire slip surface (\hyperref[assumpFOS]{A:Factor-of-Safety}).
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:effNormF}
\phantomsection
\label{GD:effNormF}
\\ \midrule
Label & Effective normal force
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{N'}}_{i}={\symbf{N}}_{i}-{\symbf{U}_{\text{b},i}}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{N'}$ is the effective normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{N}$ is the normal forces ($\frac{\text{N}}{\text{m}}$)}
\item{${\symbf{U}_{\text{b}}}$ is the base hydrostatic forces ($\frac{\text{N}}{\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & ${\symbf{U}_{\text{b}}}$ is defined in \hyperref[GD:baseWtrF]{GD:baseWtrF}.
\\ \midrule
Source & \cite{chen2005}
\\ \midrule
RefBy &
\\ \bottomrule
\end{tabular}
\end{minipage}
\paragraph{}
\label{GD:effNormFDeriv}
Derived by substituting \hyperref[DD:normStress]{DD:normStress} into \hyperref[TM:effStress]{TM:effStress} and multiplying both sides of the equation by the area of the slice in the shear-$z$ plane. Since the slope is assumed to extend infinitely in the $z$-direction (\hyperref[assumpPSC]{A:Plane-Strain-Conditions}), the resulting forces are expressed per metre in the $z$-direction.
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:resShearWO}
\phantomsection
\label{GD:resShearWO}
\\ \midrule
Label & Resistive shear force, without interslice normal and shear forces
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{R}}_{i}=\left(\left({\symbf{W}}_{i}+{\symbf{U}_{\text{g},i}} \cos\left({\symbf{β}}_{i}\right)\right) \cos\left({\symbf{α}}_{i}\right)+\left(-{\symbf{H}}_{i}+{\symbf{H}}_{i-1}+{\symbf{U}_{\text{g},i}} \sin\left({\symbf{β}}_{i}\right)\right) \sin\left({\symbf{α}}_{i}\right)-{\symbf{U}_{\text{b},i}}\right) \tan\left({φ'}_{i}\right)+{c'}_{i} {\symbf{L}_{b,i}}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{R}$ is the resistive shear forces without the influence of interslice forces ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{W}$ is the weights ($\frac{\text{N}}{\text{m}}$)}
\item{${\symbf{U}_{\text{g}}}$ is the surface hydrostatic forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{β}$ is the surface angles (${{}^{\circ}}$)}
\item{$\symbf{α}$ is the base angles (${{}^{\circ}}$)}
\item{$\symbf{H}$ is the interslice normal water forces ($\frac{\text{N}}{\text{m}}$)}
\item{${\symbf{U}_{\text{b}}}$ is the base hydrostatic forces ($\frac{\text{N}}{\text{m}}$)}
\item{$φ'$ is the effective angle of friction (${{}^{\circ}}$)}
\item{$c'$ is the effective cohesion (${\text{Pa}}$)}
\item{${\symbf{L}_{b}}$ is the total base lengths of slices (${\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & $\symbf{W}$ is defined in \hyperref[GD:sliceWght]{GD:sliceWght}, ${\symbf{U}_{\text{g}}}$ is defined in \hyperref[GD:srfWtrF]{GD:srfWtrF}, $\symbf{β}$ is defined in \hyperref[DD:angleB]{DD:angleB}, $\symbf{α}$ is defined in \hyperref[DD:angleA]{DD:angleA}, $\symbf{H}$ is defined in \hyperref[DD:intersliceWtrF]{DD:intersliceWtrF}, ${\symbf{U}_{\text{b}}}$ is defined in \hyperref[GD:baseWtrF]{GD:baseWtrF}, and ${\symbf{L}_{b}}$ is defined in \hyperref[DD:lengthLb]{DD:lengthLb}.
\\ \midrule
Source & \cite{chen2005} and \cite{karchewski2012}
\\ \midrule
RefBy & \hyperref[IM:intsliceFs]{IM:intsliceFs} and \hyperref[IM:fctSfty]{IM:fctSfty}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:mobShearWO}
\phantomsection
\label{GD:mobShearWO}
\\ \midrule
Label & Mobilized shear force, without interslice normal and shear forces
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
{\symbf{T}}_{i}=\left({\symbf{W}}_{i}+{\symbf{U}_{\text{g},i}} \cos\left({\symbf{β}}_{i}\right)\right) \sin\left({\symbf{α}}_{i}\right)-\left(-{\symbf{H}}_{i}+{\symbf{H}}_{i-1}+{\symbf{U}_{\text{g},i}} \sin\left({\symbf{β}}_{i}\right)\right) \cos\left({\symbf{α}}_{i}\right)
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{T}$ is the mobilized shear forces without the influence of interslice forces ($\frac{\text{N}}{\text{m}}$)}
\item{$i$ is the index (Unitless)}
\item{$\symbf{W}$ is the weights ($\frac{\text{N}}{\text{m}}$)}
\item{${\symbf{U}_{\text{g}}}$ is the surface hydrostatic forces ($\frac{\text{N}}{\text{m}}$)}
\item{$\symbf{β}$ is the surface angles (${{}^{\circ}}$)}
\item{$\symbf{α}$ is the base angles (${{}^{\circ}}$)}
\item{$\symbf{H}$ is the interslice normal water forces ($\frac{\text{N}}{\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & $\symbf{W}$ is defined in \hyperref[GD:sliceWght]{GD:sliceWght}, ${\symbf{U}_{\text{g}}}$ is defined in \hyperref[GD:srfWtrF]{GD:srfWtrF}, $\symbf{β}$ is defined in \hyperref[DD:angleB]{DD:angleB}, $\symbf{α}$ is defined in \hyperref[DD:angleA]{DD:angleA}, and $\symbf{H}$ is defined in \hyperref[DD:intersliceWtrF]{DD:intersliceWtrF}.
\\ \midrule
Source & \cite{chen2005} and \cite{karchewski2012}
\\ \midrule
RefBy & \hyperref[IM:intsliceFs]{IM:intsliceFs} and \hyperref[IM:fctSfty]{IM:fctSfty}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:normShrR}
\phantomsection
\label{GD:normShrR}
\\ \midrule
Label & Interslice shear forces
\\ \midrule
Units & $\frac{\text{N}}{\text{m}}$
\\ \midrule
Equation & \begin{displaymath}
\symbf{X}=λ \symbf{f} \symbf{G}
\end{displaymath}
\\ \midrule
Description & \begin{symbDescription}
\item{$\symbf{X}$ is the interslice shear forces ($\frac{\text{N}}{\text{m}}$)}
\item{$λ$ is the proportionality constant (Unitless)}
\item{$\symbf{f}$ is the interslice normal to shear force ratio variation function (Unitless)}
\item{$\symbf{G}$ is the interslice normal forces ($\frac{\text{N}}{\text{m}}$)}
\end{symbDescription}
\\ \midrule
Notes & Mathematical representation of the primary assumption for the Morgenstern-Price method (\hyperref[assumpINSFL]{A:Interslice-Norm-Shear-Forces-Linear}). $\symbf{f}$ is defined in \hyperref[DD:ratioVariation]{DD:ratioVariation}.
\\ \midrule
Source & \cite{chen2005}
\\ \midrule
RefBy & \hyperref[IM:fctSfty]{IM:fctSfty} and \hyperref[IM:nrmShrFor]{IM:nrmShrFor}
\\ \bottomrule
\end{tabular}
\end{minipage}
\medskip
\noindent
\begin{minipage}{\textwidth}
\begin{tabular}{>{\raggedright}p{0.13\textwidth}>{\raggedright\arraybackslash}p{0.82\textwidth}}
\toprule \textbf{Refname} & \textbf{GD:momentEql}
\phantomsection
\label{GD:momentEql}
\\ \midrule
Label & Moment equilibrium
\\ \midrule
Units & ${\text{N}}$
\\ \midrule
Equation & \begin{displaymath}
0=-{\symbf{G}}_{i} \left({\symbf{h}_{\text{z},i}}+\frac{{\symbf{b}}_{i}}{2} \tan\left({\symbf{α}}_{i}\right)\right)+{\symbf{G}}_{i-1} \left({\symbf{h}_{\text{z},i-1}}-\frac{{\symbf{b}}_{i}}{2} \tan\left({\symbf{α}}_{i}\right)\right)-{\symbf{H}}_{i} \left(\frac{1}{3} {\symbf{h}_{\text{z,w},i}}+\frac{{\symbf{b}}_{i}}{2} \tan\left({\symbf{α}}_{i}\right)\right)+{\symbf{H}}_{i-1} \left(\frac{1}{3} {\symbf{h}_{\text{z,w},i-1}}-\frac{{\symbf{b}}_{i}}{2} \tan\left({\symbf{α}}_{i}\right)\right)+\frac{{\symbf{b}}_{i}}{2} \left({\symbf{X}}_{i}+{\symbf{X}}_{i-1}\right)+\frac{-{K_{\text{c}}} {\symbf{W}}_{i} {\symbf{h}}_{i}}{2}+{\symbf{U}_{\text{g},i}} \sin\left({\symbf{β}}_{i}\right) {\symbf{h}}_{i}+{\symbf{Q}}_{i} \sin\left({\symbf{ω}}_{i}\right) {\symbf{h}}_{i}