scholarly journals Dynamic Process and Mechanism of the Catastrophic Taihongcun Landslide Triggered by the 2008 Wenchuan Earthquake Based on Field Investigations and Discrete Element Method Simulations

2021 ◽  
Vol 9 ◽  
Author(s):  
Xingtao Zhou ◽  
Pengfei Wei ◽  
Xiaodong Fu ◽  
Lihua Li ◽  
Xiaohui Xue
Keyword(s):  
Discrete Element Method ◽  
Wenchuan Earthquake ◽  
Numerical Models ◽  
Discrete Element ◽  
Parameter Analysis ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Field Investigations ◽  
Landslide Event ◽  
Element Method

The Taihongcun landslide, which was a remarkable geological disaster triggered by the 2008 Wenchuan earthquake, had a volume of about 2 × 106 m3 and killed about 23 people. Through detailed field investigations, basic information of topography, geological structure and stratigraphy for the landslide were acquired and key kinetic characteristics of the landslide were identified. On the basis of filed investigations, 2D numerical models with discrete element method (DEM) were established to simulate the kinematics and failure process of the landslide. To ensure the validity of the dynamic calculations, the free-field boundary condition was developed and introduced intro the DEM models. According to filed investigations and DEM simulations, the dynamic processes of the Taihongcun landslide can be divided into four phases: fragmentation, projection motion, scraping, and granular debris flow and accumulation. In addition, the parameter analysis showed that the particle bond strength had a significant influence on the runout distance and landslide debris morphology. Finally, the possible mechanism of the Taihongcun landslide was determined: a rock mass of poor quality provided the lithological basis for this landslide formation; a joint set J1 in the back scarp and a weak interlayer of carbonaceous slate and shale between the upper sliding mass and the bedrock formed the rupture boundaries of the upper source area; a strong seismic ground motion was the external excitation that triggered the destructive landslide event; additionally, hypermobility was caused by the high elevation and topographical conditions of the landslide.

scholarly journals Numerical Modeling of a Punch Penetration Test Using the Discrete Element Method

2020 ◽  
Vol 28 (2) ◽  
pp. 1-7
Author(s):  
Rouhollah Basirat ◽  
Jafar Khademi Hamidi
Keyword(s):  
Numerical Modeling ◽  
Discrete Element Method ◽  
Numerical Models ◽  
Confining Pressure ◽  
Discrete Element ◽  
Numerical Results ◽  
Strength Parameter ◽  
Penetration Test ◽  
Strength Parameters ◽  
Element Method

AbstractUnderstanding the brittleness of rock has a crucial importance in rock engineering applications such as the mechanical excavation of rock. In this study, numerical modeling of a punch penetration test is performed using the Discrete Element Method (DEM). The Peak Strength Index (PSI) as a function of the brittleness index was calculated using the axial load and a penetration graph obtained from numerical models. In the first step, the numerical model was verified by experimental results. The results obtained from the numerical modeling showed a good agreement with those obtained from the experimental tests. The propagation path was also simulated using Voronoi meshing. The fracture was created under the indenter in the first step, and then radial fractures were propagated. The effects of confining pressure and strength parameters on the PSI were subsequently investigated. The numerical results showed that the PSI increases with enhancing the confining pressure and the strength parameter of the rock, including cohesion and the friction angle. A new relationship between the strength parameters and PSI was also introduced based on two variable regressions of the numerical results.

scholarly journals Investigation of the Anisotropic Characteristics of Layered Rocks under Uniaxial Compression Based on the 3D Printing Technology and the Combined Finite-Discrete Element Method

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Fan He ◽  
Quansheng Liu ◽  
Penghai Deng
Keyword(s):  
3D Printing ◽  
Discrete Element Method ◽  
Numerical Models ◽  
Discrete Element ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Transverse Isotropic ◽  
3D Printed ◽  
Inclined Angle ◽  
Element Method

The excavation in layered rocks is an issue for a number of geoengineering applications; these kinds of rocks all exhibit transverse isotropic features due to the process of metamorphic differentiation. This paper focuses on providing two methods, i.e., the 3D printing technology and the combined finite-discrete element method, to simulate the anisotropic characteristics of layered rocks. The results showed that both the 3D-printed samples and the FDEM numerical models are considered as a good match, and both revealed that as the inclined angle increased, the UCS of the sample first decreased and then increased, showing a U-shaped pattern. The results of this paper served as a reference to the promotion of the 3D printing technology and the combined finite-discrete element method in the geotechnical engineering field and laboratory test research.

Application of the Discrete Element Method (DEM) to Evaluate Pipeline Response to Slope Movement

2016 ◽  
Author(s):  
Abdelfettah Fredj ◽  
Aaron Dinovitzer ◽  
Amir Hassannejadasl ◽  
Richard Gailing ◽  
Millan Sen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Discrete Element Method ◽  
Land Surface ◽  
Numerical Models ◽  
Discrete Element ◽  
Slope Movement ◽  
Ground Movement ◽  
Element Analysis ◽  
Element Method

The long linear nature of buried pipelines results in the risk of interaction with a range of geotechnical hazards including active slopes and land surface subsidence areas. Ground movement induced by these geotechnical hazards can subject a pipeline to axial, lateral flexural, and vertical flexural loading. The techniques to predict pipeline displacements, loads, stresses or strains are not well described in design standards or codes of practice. The results of geotechnical site observation, successive in-line inspection or pipeline instrumentation are used to infer pipeline displacement or strain accumulation and these techniques are often augmented through the application of finite element analysis. The practice of using finite element analysis for pipe-soil interaction has developed in recent years and is proving to be a useful tool in evaluating the pipeline behavior in response to ground movement. This paper considers pipeline response to geotechnical hazard-induced loading scenarios related to slope movement transverse to the pipeline axis. The details of the three-dimensional LS-DYNA-based BMT pipe-soil interaction model employing a discrete element method (DEM) are presented in this paper. The validation of the numerical models through comparison with medium-scale physical pipe-soil interaction tests are described to demonstrate that the models are capable of accurately simulating real world events. The models are further calibrated for nominal soil types to replicate the pipe-soil load displacement properties outlined in ASCE guideline recommendations by developing responses that closely agree with these results from the physical trials and engineering judgement. The utility of advanced pipe-soil interaction modelling in supporting strain-based pipeline integrity management or design is demonstrated by presenting the results of geotechnical hazard numerical simulations. These simulations are used to describe the sensitivity of pipeline displacements and strains to the demands of these geotechnical events and develop relationships between the geotechnical event key parameters and pipeline response.

Investigation of the Effect of Block Size, Shape and Freeze Bond Strength on Flexural Failure of Freshwater Ice Rubble Using the Discrete Element Method

2019 ◽  
Author(s):  
Soroosh Afzali ◽  
Rocky Taylor ◽  
Eleanor Bailey ◽  
Robert Sarracino ◽  
Marjan T. Boroojerdi
Keyword(s):  
Discrete Element Method ◽  
Size Distribution ◽  
Numerical Models ◽  
Block Size ◽  
Discrete Element ◽  
Failure Behavior ◽  
Freshwater Ice ◽  
Flexural Failure ◽  
Dem Model ◽  
Element Method

Abstract Understanding ice rubble strength and associated failure mechanics is important for a variety of engineering applications in marine ice environments, including the design and operation of coastal, offshore, subsea and floating structures. As part of the Mechanics of Ice Rubble project, recent experiments have been carried out to study the strength and failure behavior of ice rubble beams and the freeze bonds that form between individual ice blocks. These new results serve as an important guide for the development of improved numerical models. The discrete element method (DEM) is a direct modeling approach which has the potential to both describe and enhance understanding of the behavior of brittle granular materials, especially with regard to the evolution of damage towards failure. In this study we present results obtained from a newly developed model for the 3D DEM open-source code LIGGGHTS. The ice model contains normal and shear springs that operate between neighboring particles which are bonded or that overlap due to compressional stresses. Energy dissipation is accounted for by using a viscous damping model. Using this DEM model, medium-scale freshwater ice rubble punch tests have been simulated for ice rubble beams with nominal dimensions of 0.50m × 0.94m × 3.05m. Rubble specimens were generated by “raining” individual DEM ice pieces into a rectangular form and compacting the rubble mass to achieve the target porosity. Before the compacting pressure was removed, bonds between contacting blocks were introduced with parameter values chosen based on representative freeze bond experiments. The ice rubble beam was then deformed by pushing a platen vertically downward through the center of the beam until failure occurred. For the numerical simulations presented here, two types of block size and shapes have been considered: cuboid blocks generated based on the size distribution of the actual rubble, and rubble blocks generated by image processing of actual blocks of broken ice used in the comparison experiments. Results obtained for these two scenarios are compared with corresponding experimental test data. These results highlight that the DEM model is useful for estimating the flexural strength of the rubble, simulating the failure mechanism and for examining the extent to which the ice rubble beam failure is controlled by the strength of the freeze bonds. These results also provide valuable new insights regarding the importance of shape and size distribution of ice blocks on simulated ice rubble strength and failure behavior. Recommendations for future work are provided.

scholarly journals Two-Layer Red Blood Cell Membrane Model Using the Discrete Element Method

2016 ◽  
Vol 846 ◽  
pp. 270-275
Author(s):  
Sarah Barns ◽  
Emilie Sauret ◽  
Suvash Saha ◽  
Robert Flower ◽  
Yuan Tong Gu
Keyword(s):  
Blood Cell ◽  
Discrete Element Method ◽  
Red Blood Cell ◽  
Numerical Models ◽  
Single Layer ◽  
Discrete Element ◽  
Reduction Ratio ◽  
Shape Variation ◽  
Layer Model ◽  
Element Method

The red blood cell (RBC) membrane consists of a lipid bilayer and spectrin-based cytoskeleton, which enclose haemoglobin-rich fluid. Numerical models of RBCs typically integrate the two membrane components into a single layer, preventing investigation of bilayer-cytoskeleton interaction. To address this constraint, a new RBC model which considers the bilayer and cytoskeleton separately is developed using the discrete element method (DEM). This is completed in 2D as a proof-of-concept, with an extension to 3D planned in the future. Resting RBC morphology predicted by the two-layer model is compared to an equivalent and well-established composite (one-layer) model with excellent agreement for critical cell dimensions. A parametric study is performed where area reduction ratio and spring constants are varied. It is found that predicted resting geometry is relatively insensitive to changes in spring stiffness, but a shape variation is observed for reduction ratio changes as expected.

Discrete element method to model cracking for two layer systems

TAPPI Journal ◽  
2019 ◽  
Vol 18 (2) ◽  
pp. 101-108
Author(s):  
Daniel Varney ◽  
Douglas Bousfield
Keyword(s):  
Discrete Element Method ◽  
Flexural Modulus ◽  
Single Layer ◽  
Discrete Element ◽  
Flexural Stress ◽  
Layer System ◽  
Three Point Bending ◽  
Moving Force ◽  
Coating Layers ◽  
Element Method

Cracking at the fold is a serious issue for many grades of coated paper and coated board. Some recent work has suggested methods to minimize this problem by using two or more coating layers of different properties. A discrete element method (DEM) has been used to model deformation events for single layer coating systems such as in-plain and out-of-plain tension, three-point bending, and a novel moving force picking simulation, but nothing has been reported related to multiple coating layers. In this paper, a DEM model has been expanded to predict the three-point bending response of a two-layer system. The main factors evaluated include the use of different binder systems in each layer and the ratio of the bottom and top layer weights. As in the past, the properties of the binder and the binder concentration are input parameters. The model can predict crack formation that is a function of these two sets of factors. In addition, the model can predict the flexural modulus, the maximum flexural stress, and the strain-at-failure. The predictions are qualitatively compared with experimental results reported in the literature.

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