 Design Considerations
 Water level fluctuations with time
 Pore water pressure distribution
 Drain or filter
 Inflow / Out flow flux
 Solution

GTS NX has been used extensively by engineers to analyze the transient flow of homogenous and zoned embankments. One of the many key advantages that GTS NX has to offer for these applications is that it enables you to easily model very complex 2D or 3D geometry and layers of stratification.
Another unique and important advantage made possible through GTS NX is enables you to accurately model zones in which seepage gradients or velocities are high by varying the size of the elements. Complex seepage project applications such as these can only be modeled with finite element software.
With GTS NX you will be able to perform any type of complex seepage analysis investigation. These investigations include the study of pore pressure changes, the effects of precipitation and evaporation, and relief wall spacing.

Seepage analysis can be largely divided into two; the steady state analysis and transient analysis.
Steady state flow analysis is where the boundary conditions inside and outside of the ground does not change with time. Therefore, the inflow is always equal to the outflow within the analysis range. Transient analysis on the other hand, can display different inflow and outflow with time, even when the same boundary conditions as the steady state analysis are applied.
A permeable ground layer (aquifer) exists where the groundwater can seep through, and if the head difference or flux exists at the boundary, the seepage phenomenon occurs.
Seepage flow occurs along the waterway that connects through the empty pores between soil particles. This flow complies with Darcy’s law. According to this law, the seepage quantity through the soil volume is equal to the multiplication of permeability coefficient, hydraulic gradient and cross sectional area. Darcy’s law originally started from the saturated domain, but can also be applied to the unsaturated domain.
The unsaturated domain includes all nonsaturated domains, from the fully dried condition to the almost saturated condition. As the degree of saturation falls below 100% , air bubbles will also exist in the pores and if the saturation is very low, the water particles will attached between soil particles in a concave form.
Negative pore pressure is referred to as suction pressure. In most cases, suction pressure increases as the degree of saturation decreases.
Transient analysis is used when the boundary conditions inside or outside of the ground changes according to time. The main differences between transient analysis and steady state analysis are that the boundary conditions change as time passes and the fact that the transient analysis requires volumetric water content. When the underground water level goes up or down, the influence factors such as the water content in the unsaturated domain and porosity are needed.
Comparing the water filling of a reservoir between the fully dried initial state and the partially saturated state, there is significant difference in the time it takes for the seepage in the reservoir body to reach a steady state. Hence, transient analysis can be used to estimate the time it takes to saturate the interior of the body, or deduce a more economic design variable by comparing it with the saturated case.

Construction stage analysis can be used to simulate the construction process of the ground using numerical analysis. Construction stage analysis consists of multiple stages and loading/ boundary conditions, as well as elements, can be added or removed at each stage. This loading/ boundary or element change is applied at the start of each stage. GTS NX can use following types of analysis features to conduct Construction stage analysis.
StressSlope Analysis
Analysis of stress and slope stability during the construction process
Seepage Analysis
Stage by stage Steady state seepage analysis, Stage by stage Transient seepage analysis
StressSeepageSlope coupled analysis
Sequential Seepagestress analysis and Slope stability analysis during the construction process
Consolidation analysis
Consolidation analysis for environment change and construction process of embankment
Fullycoupled StressSeepage analysis
Stress analysis fully coupled with Transient seepage phenomenon
When conducting Construction stage analysis, the following should be considered.
 Addition/Removal of element
 Loading/Unloading of weight
 Change in boundary condition
 Change in rock material property
 Definition of load distribution factor
 Step by step underground water level
 DrainedUndrained analysis
 Initialization of displacement
 Stress Analysis for initial construction stage (Consider Ko condition)
 Restart

Analysis that couples the seepage phenomenon and ground stress analysis can be classified in various ways, depending on the coupling.
The simplest way is to obtain the pore water pressure distribution by conducting seepage analysis beforehand, and reflecting it in the total stress/effective stress relationship equation of the stress analysis conducted in the following step. Such analysis is called sequential analysis. This method can be used to understand the static stress state of the given steady groundwater flow. However, since deformation due to stress analysis does not influence the seepage phenomenon inversely, there is no twoway coupling.
Fullycoupled StressSeepage analysis is the twoway coupled analysis between seepage analysis and stress analysis. Both analyses are used to solve the coupled equation. It can display the pore water pressure, stress or deformation changes with time.
The consolidation analysis begins with the assumption that steady state pore water pressure can be maintained, and is used to see the changes in excess pore water pressure. In other words, this analysis is used to simulate the phenomenon of how excess pore water pressure changes with the changes in load/boundary conditions.
Fullycoupled StressSeepage analysis does not follow assumption that steady state pore water pressure is maintained. Hence, it is suitable for simulating the transient seepage phenomenon, stress analysis and stability in abnormal condition in a fully coupled form. Unlike the consolidation analysis, it is possible to define the changes in seepage boundary conditions with time, boundary flow rate etc. In other words, for Fullycoupled StressSeepage analysis, it is possible to use all the transient seepage boundary conditions, structural load and boundary conditions.
This analysis can be applied to the ground stability analysis for rainfall or the of largescale dam stability analysis for water level change. The seepage boundary conditions (Head/Flux) can all be used to analyze not only the changes in excess pore water pressure, but also the consolidation analysis that considers the total change in pore water pressure.