DEM modeling and identification of representative element volume of soil skeleton

2014 ◽  
pp. 403-408
Author(s):  
M Sadaghiani ◽  
H Jentsch ◽  
K Faulstich ◽  
P Winkler ◽  
K Witt
Keyword(s):  
Representative Element ◽  
Soil Skeleton ◽  
Representative Element Volume

scholarly journals A methodology of re-generating a representative element volume of fractured rock mass

2020 ◽  
Vol 71 (4) ◽  
pp. 347-358
Author(s):  
DANG Hong-Lam ◽  
THINH Phi Hong
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fracture Network ◽  
Hydraulic Calculation ◽  
Fractured Rock Mass ◽  
Fracture Characteristics ◽  
Mechanical Calculation ◽  
Representative Element ◽  
Representative Element Volume ◽  
Actual Fracture

In simulation of fractured rock mass such as mechanical calculation, hydraulic calculation or coupled hydro-mechanical calculation, the representative element volume of fractured rock mass in the simulating code is very important and give the success of simulation works. The difficulties of how to make a representative element volume are come from the numerous fractures distributed in different orientation, length, location of the actual fracture network. Based on study of fracture characteristics of some fractured sites in the world, the paper presented some main items concerning to the fracture properties. A methodology of re-generating a representative element volume of fractured rock mass by DEAL.II code was presented in this paper. Finally, some applications were introduced to highlight the performance as well as efficiency of this methodology.

Regularized lattice Bhatnagar–Gross–Krook model for the thermal flow in porous media

2017 ◽  
Vol 232 (3) ◽  
pp. 405-415 ◽  
Author(s):  
Zuo Wang ◽  
Jiazhong Zhang ◽  
Yan Liu ◽  
Le Wang
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Numerical Stability ◽  
Present Model ◽  
Flow In Porous Media ◽  
Thermal Flow ◽  
Representative Element ◽  
Flow And Heat Transfer ◽  
Representative Element Volume ◽  
Good Agreement

A regularized lattice Bhatnagar–Gross–Krook model for flow and heat transfer in porous media at the representative element volume scale is presented. In the model, the regularization process is extended to the existing Darcy–Forchheimer-based lattice Bhatnagar–Gross–Krook scheme. Numerical results show good agreement between the present model and the previous ones. Also, the present model shows better numerical stability than its lattice Bhatnagar–Gross–Krook counterpart.

Relationship between the representative element volume and discontinuity parameters

2020 ◽  
Vol 54 (1) ◽  
pp. qjegh2019-071
Author(s):  
Shengyuan Song ◽  
Qiang Xu ◽  
Jianping Chen ◽  
Fengyan Wang ◽  
Ying Liu ◽  
...  
Keyword(s):  
Fracture Network ◽  
Volume Density ◽  
Empirical Formulas ◽  
Representative Element ◽  
Linear Relationships ◽  
Discontinuity Orientation ◽  
Homogeneous Domains ◽  
Representative Element Volume ◽  
The Relationship ◽  
Dfn Model

We introduce an application of the discrete fracture network (DFN) model and 3D persistence to study the relationship between the representative element volume (REV) size and discontinuity information. To avoid the influence of heterogeneity on the distribution of discontinuities, the dam abutment rock mass of the Songta hydropower station is divided into eight statistically homogeneous domains based on the discontinuity orientation and trace length. An optimum DFN model is established for each homogeneous domain. Cubes of different sizes are extracted from the centre of the corresponding DFN model. Based on the discontinuity projection method, the 3D persistence values within the DFN model and each cube are calculated separately. The relative error of persistence for each cube and the DFN model are used to evaluate the size effect and to identify the REV size. Subsequently, the relationship between the determined REV size and the corresponding discontinuity information is systematically researched. Our results show that the discontinuity diameter, the volume density and the Fisher constant have separate linear relationships with the REV size. We present the empirical formulas for estimating the REV size according to the discontinuity diameter, the volume density and the Fisher constant.

scholarly journals A Novel Approach to the Analysis of the Soil Consolidation Problem by Using Non-Classical Rheological Schemes

2021 ◽  
Vol 11 (5) ◽  
pp. 1980
Author(s):  
Kazimierz Józefiak ◽  
Artur Zbiciak ◽  
Karol Brzeziński ◽  
Maciej Maślakowski
Keyword(s):  
Constitutive Models ◽  
Organic Soil ◽  
Organic Soils ◽  
Soil Consolidation ◽  
Flexible Tool ◽  
One Dimensional ◽  
Novel Approach ◽  
Soil Skeleton ◽  
The One ◽  
The Relationship

The paper presents classical and non-classical rheological schemes used to formulate constitutive models of the one-dimensional consolidation problem. The authors paid special attention to the secondary consolidation effects in organic soils as well as the soil over-consolidation phenomenon. The systems of partial differential equations were formulated for every model and solved numerically to obtain settlement curves. Selected numerical results were compared with standard oedometer laboratory test data carried out by the authors on organic soil samples. Additionally, plasticity phenomenon and non-classical rheological elements were included in order to take into account soil over-consolidation behaviour in the one-dimensional settlement model. A new way of formulating constitutive equations for the soil skeleton and predicting the relationship between the effective stress and strain or void ratio was presented. Rheological structures provide a flexible tool for creating complex constitutive relationships of soil.

scholarly journals Visualization and Quantification of the Penetration Behavior of Bentonite Suspensions into the Pore Network of non-cohesive Media by using μ-CT Imaging

2016 ◽  
Author(s):  
Britta Schoesser ◽  
Atefeh Ghorbanpour ◽  
Matthias Halisch ◽  
Markus Thewes
Keyword(s):  
Filter Cake ◽  
Pore Space ◽  
Water Pressure ◽  
Soft Soil ◽  
Theoretical Models ◽  
Bored Pile ◽  
Soil Skeleton ◽  
Bentonite Suspension ◽  
Penetration Behavior ◽  
Drill Holes

Abstract. Bentonite suspensions are an essential tool for different construction techniques in horizontal and vertical drilling, in diaphragm and bored pile walls as well as in pipe jacking and tunneling. One of the main tasks of the suspension is to prevent the surrounding ground from collapsing during the excavation process of trenches, drill holes or tunnels. In order to maintain the soil stability close to the excavation, the bentonite suspension has to counteract against the earth and water pressure. Therefore, the pressure acting in the suspension has to counter the groundwater pressure and to be transferred into an effective stress to support the soil skeleton. The creation of a pressure transfer mechanism can be achieved in two ways. A direct relation exists between the mechanism of the pressure transfer and the penetration behavior of the bentonite suspension in the subsoil. The relation of the size of the bentonite particles in the suspension and the size of the pores in soft soil is decisive. In addition, the yield strength of the bentonite suspension is a determining factor. Concerning the penetration behavior two theoretical models exist actually: formation of a filter cake and entire penetration into the pore space. If the pore space is smaller than the size of the bentonite particles, a filtration process takes place. Here, the bentonite particles agglomerate gradually at the entrance of the pore space and create a thin nearly impermeable layer. This membrane is named filter cake. If the pore space is larger than the size of the bentonite particles, the suspension penetrates into the subsoil up to a certain depth. These models have a more theoretical character due to missing visual evidence concerning the interaction of the bentonite suspension in the pore space. Here, the micro CT technique delivers a valuable contribution to this research.

scholarly journals Modelling free gas overpressure in peat layers

2020 ◽  
Vol 195 ◽  
pp. 02027
Author(s):  
Stefano Muraro ◽  
Cristina Jommi
Keyword(s):  
Unsaturated Soils ◽  
Barometric Pressure ◽  
Pressure Oscillations ◽  
Global Response ◽  
Free Gas ◽  
Soil Skeleton ◽  
Changes Over Time ◽  
Fully Coupled ◽  
Over Time ◽  
Numerical Approaches

The paper assesses fully coupled hydro-mechanical numerical approaches developed for unsaturated soils to model the effect of free gas overpressure on the response of peat layers. A simple linear model is used for the soil skeleton, however, the global response is non-linear due to changes over time of the compressibility of the solid skeleton over the compressibility of the fluid, and solubility of gas in water. The overpressure generated in foundation peat layers by barometric pressure oscillations is modelled, and the results are compared to literature data. The development of pore overpressure upon unloading is analysed as a function of the soil skeleton compressibility, and the consequences on the average stress acting on the soil skeleton are discussed.

scholarly journals p-box: a new graph model

2015 ◽  
Vol Vol. 17 no. 1 (Graph Theory) ◽  
Author(s):  
Mauricio Soto ◽  
Christopher Thraves-Caro
Keyword(s):  
Graph Theory ◽  
Graph Model ◽  
Directed Path ◽  
Outerplanar Graphs ◽  
New Model ◽  
Model Based ◽  
Representative Element ◽  
International Audience ◽  
Graph Families

Graph Theory International audience In this document, we study the scope of the following graph model: each vertex is assigned to a box in ℝd and to a representative element that belongs to that box. Two vertices are connected by an edge if and only if its respective boxes contain the opposite representative element. We focus our study on the case where boxes (and therefore representative elements) associated to vertices are spread in ℝ. We give both, a combinatorial and an intersection characterization of the model. Based on these characterizations, we determine graph families that contain the model (e. g., boxicity 2 graphs) and others that the new model contains (e. g., rooted directed path). We also study the particular case where each representative element is the center of its respective box. In this particular case, we provide constructive representations for interval, block and outerplanar graphs. Finally, we show that the general and the particular model are not equivalent by constructing a graph family that separates the two cases.

Dissociative Adsorption of Carbonaceous Gases on Ni Containing Representative Elements

2011 ◽  
Vol 696 ◽  
pp. 45-50
Author(s):  
Yoshitaka Nishiyama ◽  
Koji Moriguchi ◽  
Nobuo Otsuka
Keyword(s):  
Binary Alloys ◽  
Dissociative Adsorption ◽  
Metal Dusting ◽  
Group 14 ◽  
Group 13 ◽  
Ni Alloys ◽  
Representative Element

Laboratory metal dusting test of several Ni binary alloys containing the representative element was conducted in a simulated syngas atmosphere at 650°C for 100h. The Ni alloys containing element belonging to Group 14 and 15 in the periodic series exhibited excellent metal dusting resistance, while those containing Group 13 did not. This behavior was able to be reasonably interpreted from the Blyholder mechanism and the concept of Pauling’s electronegativity.

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