Estimation of granular flow impact force on rigid wall using material point method

Landslides and avalanches cause loss of lives, as well as generate significant economic cost. Protection barriers help reduce the impact of such events. However, the design of the barriers requires the prediction of the landslide flow trajectory and the estimation of impact force. Material Point Method appears to have great potential for estimating those, since it can account for large displacement nature of sediment flows and their nonlinear behaviour. Therefore, it may be able to capture the complex interaction of landslides or avalanches with the ground and structures. This study focuses on simulating granular flows with Generalized Interpolation Material Point Method. The calculations use a constitutive model inspired by the Bagnold theory of granular flow [1] to model sand landslide / avalanche experiment [2] with sand treated as a linear elasto-plastic material. Shown simulations aim was to replicate the experiment. In particular, the paper focuses on estimation of the impact force of sand flow on a fixed rigid wall. Such force estimation is a first step to validate the Generalized Interpolation Material Point Method for use as a tool for the design of barriers defending against landslides and avalanches

Estimation of granular flow impact force on rigid wall using material point method

Landslides and avalanches cause loss of lives, as well as generate significant economic cost. Protection barriers help reduce the impact of such events. However, the design of the barriers requires the prediction of the landslide flow trajectory and the estimation of impact force. Material Point Method appears to have great potential for estimating those, since it can account for large displacement nature of sediment flows and their nonlinear behaviour. Therefore, it may be able to capture the complex interaction of landslides or avalanches with the ground and structures. This study focuses on simulating granular flows with Generalized Interpolation Material Point Method. The calculations use a constitutive model inspired by the Bagnold theory of granular flow [1] to model sand landslide / avalanche experiment [2] with sand treated as a linear elasto-plastic material. Shown simulations aim was to replicate the experiment. In particular, the paper focuses on estimation of the impact force of sand flow on a fixed rigid wall. Such force estimation is a first step to validate the Generalized Interpolation Material Point Method for use as a tool for the design of barriers defending against landslides and avalanches

A simple transformation method in skewness reduction

Statistical analysis of non-normal data is usually more complicated than that for normal distribution. In this paper, a simple root/power transformation technique developed by Niaki, et al [1] is extended to transform right and left skewed distributions to nearly normal. The value of the root/power is explored such that the skewness of the transformed data becomes almost zero with an acceptable error. The proposed method is then compared to the well-known and complicated Box, et al [2] transformation method for different left and right skewed distributions using Monte Carlo simulation. While the proposed procedure is easy to understand and to implement, the results of the simulation study show that it works as good as the Box-Cox method

Enhancing Constitutive Models for Soils: Adding the Capability to Model Nonlinear Small Strain in Shear

The deviatoric stress-deviatoric strain relationship in soils is highly nonlinear, especially in the small strain range. However, the constitutive models which aim to replicate the small strain nonlinearity are often complex and rarely used in geotechnical engineering practice. The goal of this study is to offer a simple way for updating the existing constitutive models, widely used in geotechnical practice, to take into account the small strain shear modulus changes. The study uses an existing small strain relationship to derive a yield surface. When the yield surface is introduced to an existing soil model, it enhances the model with the nonlinear deviatoric stress-deviatoric strain relationship in the small strain range. The paper also gives an example of such a model enhancement by combining the new yield surface with the Modified Cam Clay constitutive model. The validation simulations of the undrained triaxial tests on London Clay and Ham River sand with the upgraded constitutive models replicate the experiments clearly better than the base models, without any changes to existing model parameters and the core source code associated with the base model