Note to testers

VPI software is currently in beta testing stage. If you wish to test the software and helps us move forward, please leave a comment on this page or contact us at one of the following addresses: Dave Cebon - dc29@hermes.cam.ac.uk Riccardo Isola - riccardo.isola@nottingham.ac.uk Thanks, The VPI tea...

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permanent behaviour

Permanent deformation in UGMs is mainly related to resilient stresses or strains and number of load cycles. The effects of these two factors are often separated and the models for predicting permanent deformations can assume the form of:                                                                                                               ...

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Resilient Behaviour

In dealing with granular materials, the elastic properties are often defined by the resilient modulus (which replaces the modulus of elasticity to indicate the nonlinearity of the behaviour) and Poisson’s ratio. A common approach in dealing with the stress dependency of granular materials stiffness is the K-θ model, which expresses resilient modulus as a function of the sum...

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UGMs - Introduction

Over the years, many researchers have studied the complex behaviour of granular materials, using laboratory and in situ testing techniques. An extensive literature review was carried out by Lekarp et al. (2000) to collect findings from previous research and summarize in two companion papers the state of knowledge on resilient and plastic properties of granular materials. In...

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Results 2

Normalised Aggregate Force and Fourth-Power Forces Figure 1 is a comparative plot of the fleet normalised aggregate forces generated by the four simulation methods. Figure 1: Comparison of fleet normalised aggregate force histories for each of the four simulated vehicle fleets The ‘reference’ and ‘target’ time histories agree very well, while the time...

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Spatial repeatability 2

Spatial repeatability arises because trucks are similar in weights, dimensions, and dynamic characteristics and travel at similar speeds. As a result, each vehicle will apply its peak forces at approximately the same places along the pavement surface (Cole, Cebon 1992). Cole et al. defined the spatial repeatability index (SRI) as the correlation coefficient between a dynamic...

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Examples 2

Example 1 – Full depth crack A full-depth crack allows the water to reach the top of the granular layer, saturating it. In order to model how the moisture spreads from this point throughout the layer, we keep the top left element of the structure saturated (Figure 1 to Figure 3). Figure 1: Moisture infiltration through a full-depth crack – t=0 ...

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Variably Saturated flow

Numerous numerical models have been developed for simulating water movements in materials with various degrees of saturation. Clement et al (1994) reviewed many of them underlining the most common shortcomings. In most applications, the pressure-based form of the variably saturated flow equation through homogeneous and isotropic porous media is used (Cooley, 1983; Huyakorn...

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fenv calculation 2

The inputs are organised in three hierarchical levels of detail, level 1 being the most accurate where most parameters are directly measured and level 3 being the simplest where only few parameters need to be known and are used to estimate everything else. As noted before, the relationship between suction and degree of saturation for a soil is described by the Soil-Water...

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