2
phenomenon can affect the outcome and, in some situa-
tions, alter results.
Generally, in natural slopes, a boundary line divides the
unsaturated soil and the saturated soil. Above the line, the
pore water pressure of the unsaturated soil is negative to
zero, while the water pressure of the saturated soil below the
boundary line is positive (Fredlund and Rihardjo, 1993)
It was found that the development of pore fluid pressures
within soil masses, influenced by both mechanical and
pyshico-chemical effects, affects the magnitude of inter-
granular or effective stresses. These inter-granular stresses
play a crucial role in controlling the shear and compression
behavior of soil in many instances (Mitchell 2013)
The principle of effective stress is one of the most essen-
tial concepts of modern soil mechanics. It has been found
useful as a basis for the understanding of stress and strain
characteristics of soils and has become increasingly impor-
tant in practical engineering problems. An increase in pore
water pressure has caused so many landslides and slope fail-
ures in both mining and civil engineering.
In the mining industry, one major cause of tailings dam
failure has been pore pressure increase. It was found that
gradual rise in saturation levels and pore pressure can initi-
ate static liquefaction and flow sliding failures (Eckersley
1990 Martin and McRoberts 1999).Slope stability is influ-
enced by excess pore water pressure, which can result from
factors such as prolonged and heavy rainfall, rising ground-
water, or earthquakes. (Chin-C and Chien-Li 2013). Some
efforts have also been made to develop a predictive warn-
ing system for rainfall-induced slope failures (e.g., Johnson
and Sitar 1990 Anderson and Thallapally 1996 Rahardjo
1999 Fannin and Jaakkola 1999). Previous studies have
shown that Soil-water characteristic curves (SWCC) and
soil permeability functions pertinent to specific soils along
with numerical analysis tools, can be used to capture the
timing of wetting front propagation and the resulting slope
failures (Cai and Ugai, 2004 Kim et al., 2004 Gerscovich
et al., 2006 Cho, 2009 Tu et al., 2009 Montrasio et al.,
2009 Rahimi et al., 2010).
Spence and Gumar (1997), observed an increase in
the pore water pressure in small scale laboratory flow slides
using flumes test. They concluded that the pore water pres-
sures are reasonably predicted by using the Coulomb fail-
ure criterion and assuming equilibrium of the driving and
resisting forces.
A significant disadvantage of many non-contact mea-
surement and experiment is the high cost of materials and
tools. Finite element method is a powerful tool that can
be used to model such laboratory experiments. Besides,
numerical methods such as finite element method can be
used to study the boundary conditions and scenarios which
are not easy to implement in the laboratory tests. However,
it is necessary to use mathematics to comprehensively
understand and quantify any physical aspects such as struc-
tural or fluid behavior.
Numerical modeling techniques rely on mathemati-
cal algorithms, employing approximations and appropriate
assumptions to streamline complex problems. These models
further explore the impact of factors such as slope geome-
try, soil properties, and the dynamics of water level changes.
Numerical studies have been generally used to simulate and
provide an improved understanding of slope performance
and failure mechanisms related to water changes. (Jia et al.
2009).
The use of dye to trace fluid flow is common in the
automobile, health, and beauty industry. It helps in detect-
ing traces in its path and is very fundamental when a vis-
ible mark is needed. In soil mechanics, it can help with
identifying traces of water movement. Seepage forces are
generated on the individual soil grains when water flows
through soil. These forces, if large enough, can reduce the
effective stresses to zero, essentially making the soil a dense
liquid called quicksand. Infiltration and Seepage analyses
are important tools to assess the susceptibility of seepage
failure in dams and to study hydraulic conditions for ana-
lyzing the stability of dam slopes (Chen and Zhang, 2006).
In this research, a finite element analytical tool was
used to simulate a simple slope failure caused by an increase
in pore-water pressure. A laboratory experiment is con-
ducted using the same soil parameters and properties and
compared to the results of the analytical tool when there is
a failure. Moreover, seepage was studied.
2.1 Objectives
The main objectives of this research are to:
1. Study the flow of water through a sandy soil slope.
2. Detect and monitor seepage of water using an
ultraviolet (UV) dye.
3. Induce slope failure by increasing pore-water pres-
sure and monitoring at the laboratory.
4. Create a numerical model using Slide code.
MATERIALS AND METHODS
3.1 Introduction
This chapter explains the materials and experimental meth-
ods used. The soil properties are discussed first, and then
the process of making the experimental test box. After
these, the procedures of the experiments are explained in
depth. Finally, filming with the camera for comparison is
phenomenon can affect the outcome and, in some situa-
tions, alter results.
Generally, in natural slopes, a boundary line divides the
unsaturated soil and the saturated soil. Above the line, the
pore water pressure of the unsaturated soil is negative to
zero, while the water pressure of the saturated soil below the
boundary line is positive (Fredlund and Rihardjo, 1993)
It was found that the development of pore fluid pressures
within soil masses, influenced by both mechanical and
pyshico-chemical effects, affects the magnitude of inter-
granular or effective stresses. These inter-granular stresses
play a crucial role in controlling the shear and compression
behavior of soil in many instances (Mitchell 2013)
The principle of effective stress is one of the most essen-
tial concepts of modern soil mechanics. It has been found
useful as a basis for the understanding of stress and strain
characteristics of soils and has become increasingly impor-
tant in practical engineering problems. An increase in pore
water pressure has caused so many landslides and slope fail-
ures in both mining and civil engineering.
In the mining industry, one major cause of tailings dam
failure has been pore pressure increase. It was found that
gradual rise in saturation levels and pore pressure can initi-
ate static liquefaction and flow sliding failures (Eckersley
1990 Martin and McRoberts 1999).Slope stability is influ-
enced by excess pore water pressure, which can result from
factors such as prolonged and heavy rainfall, rising ground-
water, or earthquakes. (Chin-C and Chien-Li 2013). Some
efforts have also been made to develop a predictive warn-
ing system for rainfall-induced slope failures (e.g., Johnson
and Sitar 1990 Anderson and Thallapally 1996 Rahardjo
1999 Fannin and Jaakkola 1999). Previous studies have
shown that Soil-water characteristic curves (SWCC) and
soil permeability functions pertinent to specific soils along
with numerical analysis tools, can be used to capture the
timing of wetting front propagation and the resulting slope
failures (Cai and Ugai, 2004 Kim et al., 2004 Gerscovich
et al., 2006 Cho, 2009 Tu et al., 2009 Montrasio et al.,
2009 Rahimi et al., 2010).
Spence and Gumar (1997), observed an increase in
the pore water pressure in small scale laboratory flow slides
using flumes test. They concluded that the pore water pres-
sures are reasonably predicted by using the Coulomb fail-
ure criterion and assuming equilibrium of the driving and
resisting forces.
A significant disadvantage of many non-contact mea-
surement and experiment is the high cost of materials and
tools. Finite element method is a powerful tool that can
be used to model such laboratory experiments. Besides,
numerical methods such as finite element method can be
used to study the boundary conditions and scenarios which
are not easy to implement in the laboratory tests. However,
it is necessary to use mathematics to comprehensively
understand and quantify any physical aspects such as struc-
tural or fluid behavior.
Numerical modeling techniques rely on mathemati-
cal algorithms, employing approximations and appropriate
assumptions to streamline complex problems. These models
further explore the impact of factors such as slope geome-
try, soil properties, and the dynamics of water level changes.
Numerical studies have been generally used to simulate and
provide an improved understanding of slope performance
and failure mechanisms related to water changes. (Jia et al.
2009).
The use of dye to trace fluid flow is common in the
automobile, health, and beauty industry. It helps in detect-
ing traces in its path and is very fundamental when a vis-
ible mark is needed. In soil mechanics, it can help with
identifying traces of water movement. Seepage forces are
generated on the individual soil grains when water flows
through soil. These forces, if large enough, can reduce the
effective stresses to zero, essentially making the soil a dense
liquid called quicksand. Infiltration and Seepage analyses
are important tools to assess the susceptibility of seepage
failure in dams and to study hydraulic conditions for ana-
lyzing the stability of dam slopes (Chen and Zhang, 2006).
In this research, a finite element analytical tool was
used to simulate a simple slope failure caused by an increase
in pore-water pressure. A laboratory experiment is con-
ducted using the same soil parameters and properties and
compared to the results of the analytical tool when there is
a failure. Moreover, seepage was studied.
2.1 Objectives
The main objectives of this research are to:
1. Study the flow of water through a sandy soil slope.
2. Detect and monitor seepage of water using an
ultraviolet (UV) dye.
3. Induce slope failure by increasing pore-water pres-
sure and monitoring at the laboratory.
4. Create a numerical model using Slide code.
MATERIALS AND METHODS
3.1 Introduction
This chapter explains the materials and experimental meth-
ods used. The soil properties are discussed first, and then
the process of making the experimental test box. After
these, the procedures of the experiments are explained in
depth. Finally, filming with the camera for comparison is