Integrated into the GeoStudio Suite

QUAKE/W is integrated into the GeoStudio suite, and therefore has access to the GeoStudio features for creating your model, analyzing it, and viewing results.

Dynamic Analysis of Earth Structures

QUAKE/W can be used to analyze earth structures subjected to earthquake shaking or dynamic point forces from a blast or a sudden impact load. QUAKE/W determines the motion and excess pore-water pressures that arise due to shaking. Therefore, it is designed primarily for assessing:

• The stability of slopes that are subjected to inertial forces arising from earthquake shaking
• The liquefaction potential of earth structures subjected to earthquake shaking
• The potential permanent deformation associated with earthquake shaking

Comprehensive Formulation

QUAKE/W uses a finite element-based formulation based on direct integration in the time domain. When analyzing earth structures subjected to earthquake shaking, this means integrating a set of time intervals from the start to the end of the defined earthquake record. Alternative time intervals can be used for other dynamic analysis types.

Typical Applications

QUAKE/W can model the dynamic behavior of almost any earth structure you will encounter in your geotechnical, civil, and mining engineering projects, including:

• Earth embankment dams
• Natural soil and rock slopes
• Loose ground deposits
• Estimation of post-earthquake deformation
• Impact loads from dynamic blasting
• Any natural, near-horizontal ground sites with potential for excess pore water pressure generation

Constitutive Models and Material Properties

Three constitutive models are supported: Linear-Elastic, Equivalent Linear, and an effective stress Non-Linear model. The Cyclic Stress Ratio (CSR) approach is used for calculating excess pore-pressures arising from dynamically induced shear stresses.

Generalized material property functions allow you to use any laboratory or published data. This includes functions for the overburden correction function (Ks), shear stress correction (Ka), cyclic number, pore-water pressure, damping ratio, and G modulus reduction. When QUAKE/W performs an Equivalent Linear analysis, the Damping Ratio and G modulus vary with cyclic strain for successive iterations.

Collapse Surface Definition

A granular soil with a collapsed grain structure can fail at strengths below its conventional strength as defined by effective c' and φ' parameters. Using QUAKE/W, you can simulate this liquefaction potential by defining a collapse surface and steady-state strength for the material. QUAKE/W will use these properties to identify zones of liquefaction within the material.

Estimate Material Properties for Typical Materials

Most material property functions can be estimated using built-in properties for typical materials. The estimation process requires only fundamental material information, such as the N exponent for pore-water pressure functions, confining stress and plasticity index for G-reduction functions, and typical soil classifications for Cyclic number functions.

Comprehensive Range of Generalized Boundary Conditions

QUAKE/W supports a comprehensive list of boundary condition options including normal/tangential stress, X-Y stress, hydrostatic pressure, displacement, force, or spring boundaries. In keeping with the entire GeoStudio suite, QUAKE/W makes broad use of generalized functions for boundary condition definition. As such, actual field data over time or user-specified functional relationships can be pasted into QUAKE/W. For example, acceleration or velocity data over time can be used to create a displacement boundary function.

Insitu Condition Options

Insitu stresses can be established using either Poisson’s ratio or by specifying an initial K ₀ value for the material. This provides the ability to model heavily over-consolidated soils in which the horizontal stresses exceed the vertical.

Import Earthquake records

QUAKE/W allows you to import and scale earthquake time history records. Once the horizontal or vertical earthquake accelerations are imported, the peak acceleration and duration can be modified in order to adjust the values used in the QUAKE/W analysis to represent site-specific conditions.

Structural Elements

Structural elements can in included in a QUAKE/W analysis to investigate the effect of both axial and flexural structural stiffness on the dynamic response of the earth structure.

Integrate with SLOPE/W for Newmark Analyses

A Newmark analysis seeks to compute the potential permanent deformation in earth slopes arising from dynamic earthquake forces. The QUAKE/W computed dynamic forces can be used in SLOPE/W to compute yield accelerations and potential permanent deformations for each trial slip surface. The stability results can be sorted to identify the trial slip surface with the greatest potential permanent deformation.

Integrate with SLOPE/W to Model Excess Pore-Pressures and Stability

Excess pore-pressures computed by QUAKE/W can be considered in a SLOPE/W analysis to examine the effect of the elevated pore-water pressures on stability.

Integrate with SLOPE/W to Model Liquefaction Zones

Areas indicated as potential liquefaction zones in QUAKE/W can be evaluated in a SLOPE/W analysis to assess the influence of liquefaction on stability, given the associated liquefied strength reduction factor.

Integrate with SEEP/W to Dissipate Excess Pore-Water Pressures

The time required for dissipation of excess pore-water pressures generated during an earthquake can be determined by inputting QUAKE/W results into a SEEP/W analysis.

Integrate with SIGMA/W to Model Permanent Deformation

Liquefaction causes large strength reductions, which may lead to permanent deformations following an earthquake. Information on potential liquefaction zones generated in a QUAKE/W analysis can be used to compute the degree of permanent deformation with a stress-redistribution analysis in SIGMA/W.

Powerful Graphing and Contouring Options

Graphing is critical for the interpretation of stress-strain problems. The powerful contouring and graphing options in GeoStudio make it possible to plot both static and dynamic conditions such as stress, strain, pore-water pressure, acceleration, velocity and deformation at a point with time during the earthquake shaking. All of this data can be exported or copy/pasted directly into spreadsheet software.

View both Relative and Absolute Results

View displacements, velocities and accelerations as relative values (the finite element results relative to a fixed base) or as absolute values (the results added to the earthquake record). Relative data is used to compute, for example, excess pore-pressure, while absolute information is used primarily to visualize the earthquake motion.

View Deformed Mesh and Liquefaction Zone

Interpretation of the results is enhanced through the ability to view a deformed mesh, displacement vectors, and the shading of potentially liquefiable zones. A sequence of deformed meshes over time can be combined to make a movie of the earthquake motion.

Spectral Analysis at History Points

Look at the complete displacement, velocity and acceleration history record at key “history” points that can be defined at any point in the domain. Once the analysis is complete, you can perform a spectral analysis at these points to study the ground motion frequency and seismic characteristics.

View Stresses in a Mohr Circle

A Mohr Circle and associated space-force diagram can be plotted at any gauss point or node to further interrogate the results.

Sensitivity Analysis with QUAKE/W

A sensitivity analysis can be readily conducted with QUAKE/W by cloning multiple analyses using the Analysis Tree and then making slight changes to each one.