## Slope stability analysis

### SLOPE/W effectively analyzes both simple and complex problems for a variety of slip surface shapes, pore-water pressure conditions, soil properties, analysis methods and loading conditions.

With this comprehensive range of features, SLOPE/W can be used to analyze almost any slope stability problem you will encounter in your geotechnical, civil, and mining engineering projects.

### Pore-Water Pressure

Pore-water pressures can be defined using
piezometric lines, spatial functions, or the results from other GeoStudio finite
element analyses. Values
can be displayed as contours on the geometry to reveal PWP values used in the analysis.

### Rapid Drawdown

Rapid drawdown analysis can be conducted
using the pore-water pressures defined using piezometric lines, transient finite
element GeoStudio analyses, or the multi-stage rapid drawdown technique.

### Material Models

SLOPE/W supports a comprehensive list of material models including Mohr-Coulomb, undrained, high strength,
impenetrable, bilinear, anisotropic strength,
SHANSEP, spatial Mohr-Coulomb and more.

### Limit State Design

Limit state design or load resistance
factor design is handled by specifying partial factors on
permanent/variable loads, seismic coefficients, material properties, reinforcement inputs and more.

### Eurocode Design Case

SLOPE/W can be used to complete a stability analysis with the objective being to check an ultimate limit state in accordance with various limit state design approaches such as Eurocode 7, Norwegian Standard NS 3480, and British Standard 8006. The stability analysis is completed with partial factors applied to characteristic loads and soil strength parameters.

### James Bay Case History

This article looks at the SLOPE/W probabilistic analysis capabilities relative to the James Bay hydroelectric project. It required the construction of fifty kilometers of dykes on soft and sensitive clay. Divergent views were prevalent regarding the selection of safety factors and strength properties. The project has consequently become an important and often-cited case history.

### Reinforcement with Soil Nails

The purpose of this illustrative example is to show how soil nails can be used to improve the stability of a slope. Features of this simulation include: Morgenstern-Price analysis method, homogenous material using the Mohr Coulomb soil model, a dry slope with no pore-water pressure, four sloping soil nails, and the entry and exit slip surface option.

### Stability of an MSE Wall

Mechanically stabilized earth (MSE) walls are structures for retaining the earth under bridges, highways, and waterfront properties, to name a few. Designing a MSE wall requires consideration of the geometric configuration and reinforcement requirement to ensure both internal and external stability.

Create a SLOPE/W analysis and set up the problem workspace. Choose options for limit equilibrium or finite element stress methods, defining pore-water pressure, trial slip surfaces, tension cracks, probabilistic and sensitivity, pseudo-static loading, partial factors, convergence criteria, and more.

Create a SLOPE/W analysis, and then draw the regions in your domain using CAD-like drawing tools, including drawing polygon and circular regions, coordinate import, copy-paste geometric items, length and angle feedback, region splitting and merging, and direct keyboard entry of coordinates, lengths, and angles. Alternatively, import AutoCAD DWG or DXF files directly into GeoStudio to create your domain geometry.

Define the material properties for your analysis, assign them to regions on the domain, and then define your initial pore-water conditions. Select from a comprehensive list of soil and rock material models including Mohr-Coulomb, undrained, high strength, impenetrable, bilinear, strength as a function of depth, anisotropic strength, generalized shear-normal function, SHANSEP, and generalized shear-normal function (for typical rock material models including Hoek-Brown). Define the pore-water pressure conditions as either piezometric lines, spatial functions, finite element computed, or Ru and B-bar approaches.

Define slope reinforcement properties to simulate ground anchors, soil nails, piles, or geosynthetics. Define surcharge loads to simulate a pressure applied over a portion of the ground surface, such as a footing. Any other loads can be modelled on the domain as a point load. You can also specify seismic loading on the domain by setting horizontal and vertical coefficients that represent a force created by seismic or earthquake accelerations.

Define a set of trial slip surfaces that SLOPE/W will use for computing a critical factor of safety. A number of options for specifying slip surfaces are available, including as entry and exit zones along the ground surface, a grid of slip surface centers and radius tangents, blocks of slip surface intersection points, or pre-defined slip surface line segments.

## The power of integration

### SLOPE/W offers simple but powerful analytical capabilities when used in combination with other GeoStudio products.

### SEEP/W results in SLOPE/W

Using SEEP/W finite element pore-water pressures in SLOPE/W makes it possible to deal with complex saturated/ unsaturated conditions or transient pore-water pressure conditions. From a transient analysis, we know the pore-water pressure conditions at various points in time. Using these time- varying pore-water pressure results in SLOPE/W makes it possible to look at the changes in stability with time.

### SIGMA/W stresses in SLOPE/W

There are many geotechnical cases where it is desirable to not only perform a deformation analysis, but also to look at stability. In other instances, a SLOPE/W limit equilibrium stability analysis alone is inadequate. For cases like this, the SIGMA/W computed stresses can be used in SLOPE/W to compute the safety factors.

### SIGMA/W pore-water pressures in SLOPE/W

Simulating the placement of fill in SIGMA/W, for example, may create excess pore-water pressures in the foundation. These SIGMA/W excess pore-water pressures can be used in SLOPE/W to analyze the stability during construction and at the end of construction. This could help with designing sub-surface draining or staging the loading.

### QUAKE/W results in SLOPE/W

Earthquake shaking of ground structures creates inertial forces that may affect the stability of the structures. The shaking may also generate excess pore-water pressures. Both the dynamic stress conditions and the generated pore-water pressures can be taken into SLOPE/W to study how an earthquake affects the earth structure stability and deformation.

### VADOSE/W results in SLOPE/W

Using VADOSE/W computed pore-water pressures in SLOPE/W makes it possible to model the effects of climate-controlled, net infiltration on stability.