检索结果-内蒙古大学图书馆

Movement Morphology and Mechanical Characteristics of Small Landslide Debris Flow

NATURAL HAZARDS REVIEW 2025年第1期26卷

作者： Ding, Ruixiang Xiong, Guohua Zhong, Peng Ma, Hongqiang Ren, Feng Liang, Fachun China Univ Petr East China Coll Pipeline & Civil Engn Qingdao 266400 Shandong Peoples R China East China Jiaotong Univ Sch Civil Engn & Architecture Nanchang 330013 Jiangxi Peoples R China China Univ Petr East China Coll Pipeline & Civil Engn Qingdao 266400 Shandong Peoples R China

The structural damage of buried pipelines is caused by the strong impact and pressure of landslide debris flow (LDF), which in turn affects the integrity and function of a pipeline. To ensure the safety of natural gas buried pipelines in areas with frequent LDF, the morphology changes and mechanical characteristics of LDF are studied during its movement process, and relevant mechanical predictive models are established. Firstly, a numerical simulation model of LDF movement is established by using the discrete-element method (DEM). The model parameters were calibrated through experiment, and the error was within +/- 15%. Secondly, the morphology of LDF is discussed in the process of movement. The results showed that the morphology of LDF is semiellipsoidal. The top-view shape perpendicular to the slope surface presents as elliptical, and its axis length increases first and then decreases. Meanwhile, combined with the movement morphology of LDF, the mechanical characteristics were studied between LDF and mountain slope surface. After the LDF moves for 4 s, the pressure on the slope surface on the elliptical axes shows a parabola shape. In short, the pressure of LDF on the disaster area presents a semiellipsoidal distribution. Lastly, the prediction model for LDF average pressure was established on the disaster area through the data-fitting method. The error was within +/- 10% compared with the simulation results, which can meet the engineering requirements. This study can provide a theoretical basis for the laying of buried natural gas pipelines through LDF disaster areas.

关键词： Landslide debris flow discrete-element method Movement morphology Mechanical characteristics Risk analysis Safety engineering

来源：评论

学校读者我要写书评

暂无评论

Particle Size Effect on the Evolution of Stress and Fabric in Granular Materials under True Triaxial Conditions

引用

INTERNATIONAL JOURNAL OF GEOMECHANICS 2025年第4期25卷

作者： Liu, Yang Yan, Zhouyi Univ Sci & Technol Beijing Dept Civil Engn Beijing 100083 Peoples R China

Particle size significantly influences the macroscopic and microscopic responses of granular materials. The main purpose of previous works was to investigate the macroscopic response, but the influence of particle size on the evolution of microstructures is often ignored. The particle size effect becomes more complex under true triaxial stress conditions. Using the discrete-element method, a series of true triaxial numerical tests were carried out in this study to investigate the particle size effect. The mechanism of the particle size effect was elucidated from the perspective of similarity theory first. Then, the evolution of the stress and fabric for the whole, strong, and weak contact network was investigated. Meanwhile, the role played by strong and weak contacts in the particle size effect was discussed. The numerical results demonstrate that the peak stress ratio of the granular materials is enhanced as the particle size increases, which is caused by strong contacts. The peak stress ratio shows a linear relationship with particle size. The particle size effect on the strength is greater under the triaxial compression condition than under the triaxial extension condition. The proportion of sliding contacts within weak contacts gradually increases as the particle size increases. At nonaxisymmetric stress conditions, stress and fabric display noncoaxial behavior on the pi-plane, and an increase in particle size enhances the noncoaxiality, which mainly originates from the weak contacts.

关键词： Granular materials Particle size effect discrete-element method True triaxial test Strong and weak contacts

来源：评论

学校读者我要写书评

暂无评论

Predictions for the Multiscale Elastic Performance of Solid Waste Aggregate Concrete

引用

JOURNAL OF MATERIALS IN CIVIL ENGINEERING 2025年第2期37卷

作者： Li, Chao Zhou, Mei Li, Yang Zhang, Kai Yu, Yanfu Liao, Yue Peng, Lei Liaoning Tech Univ Coll Civil Engn 47 Zhonghua Rd Fuxin 121000 Liaoning Peoples R China Key Lab Liaoning Coal Gangue Utilizat & Energy Ef 47 Zhonghua Rd Fuxin 121000 Liaoning Peoples R China Engn Res Ctr Liaoning Coal Based Solid Waste Util 47 Zhonghua Rd Fuxin 121000 Liaoning Peoples R China Jinzhou Urban Planning & Design Inst Co Ltd 44-2 Baodi Zone C Jinzhou 121000 Liaoning Peoples R China Cent South Univ Sch Civil Engn 932 South Lushan Rd Changsha 410083 Hunan Peoples R China

To investigate the elastic properties of bulk solid waste aggregates and their impact on the elastic performance of mixed concrete, mechanical tests were conducted on 32 types of natural and solid waste aggregates, along with their corresponding mixed concretes and internal mortars. These tests were complemented with X-ray diffraction (XRD), scanning electron microscope (SEM), mercury intrusion porosimetry (MIP) analyses, microhardness assessments, and a discrete-element simulation. The results show that the elastic modulus of coarse aggregates significantly influences the overall elastic modulus of concrete, more so than that of the mortar and interfacial transition zones. The secant modulus, derived from the standard aggregate crushing value test, substantially reflects the actual elastic properties of the bulk aggregates within concrete, thus enabling rapid predictions of multiscale elastic performance of concrete. Furthermore, incorporating a water influence coefficient into the predictive model not only enhances prediction accuracy but also aids in identifying aggregates prone to softening within the concrete.

关键词： Secant modulus of bulk aggregate Water effect coefficient of aggregate Elastic modulus Poisson's ratio Aggregate crushing value discrete-element method

来源：评论

学校读者我要写书评

暂无评论

Effects of Particle Shape on the Shear Behavior and Breakage of Ballast: A DEM Approach

引用

INTERNATIONAL JOURNAL OF GEOMECHANICS 2025年第1期25卷

作者： Chen, Jing Indraratna, Buddhima Vinod, Jayan S. Ngo, Trung Liu, Yangzepeng Zhejiang Univ Dept Civil Engn Hangzhou 310058 Peoples R China Univ Wollongong Fac Engn & Informat Sci Ctr Geomech & Railway Engn Wollongong NSW 2522 Australia Univ Technol Sydney Transport Res Ctr Ultimo NSW 2007 Australia Univ Technol Sydney Transport Res Ctr Sch Civil & Environm Engn Ultimo NSW 2007 Australia China Railway 11th Bur Grp Co Ltd Wuhan 430061 Peoples R China

This paper presents results obtained from the discrete-element method (DEM) to study the effects of particle shape on the shear behavior and breakage of ballast aggregates. In this study, a series of direct shear tests have been performed on granular assemblies having various shape sphericity and roundness values. A clump-based degradation (breakage) model is incorporated into the DEM simulation to capture the breakage of aggregates during shearing. The results show that the decrease of particle sphericity and roundness results in an improvement in the shear performance of granular assemblies but subsequent exacerbation in particle breakage, which in turn reduces the shear strength and volumetric dilation. The breakage of particles localizes within an inclined band, with the width and inclination angle of the band increasing in assemblies comprising particles of low sphericity and roundness. A micromechanical analysis is conducted to examine the anisotropy of internal structures and particle motions in granular assemblies. It is observed that both the shape of particles and their breakage significantly influence these factors. Through microscopic analysis, a fundamental governing mechanism of particle shape effects on the shear strength and the breakage of granular materials is investigated at the macroscopic scale.

关键词： Particle breakage Sphericity and roundness Shear behavior Anisotropy of internal structure discrete-element method

来源：评论

学校读者我要写书评

暂无评论

DEM-DFM Modeling Suffusion of Granular Soils under Triaxial Compression

引用

INTERNATIONAL JOURNAL OF GEOMECHANICS 2025年第2期25卷

作者： Wang, Tuo Wang, Pei Yin, Zhen-Yu Zhang, Fengshou Xu, Changjie East China Jiaotong Univ Inst Geotech Engn Sch Civil Engn & Architecture Nanchang 330013 Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong 999077 Peoples R China Tongji Univ Minist Educ Key Lab Geotech & Underground Engn Shanghai 200092 Peoples R China Tongji Univ Coll Civil Engn Dept Geotech Engn Shanghai 200092 Peoples R China

Suffusion of soils is one of the common hazards in geotechnical and ocean engineering. The influence of the stress condition of soils on suffusion, however, remains unexplored in previous studies. In this study, systematical numerical simulations are performed to investigate the suffusion of soils subjected to triaxial compression using the coupled discrete-element method (DEM) and the dynamic fluid mesh (DFM) approach. By imposing a downward fluid flow, the suffusion in seven gap-graded soil samples with a wide range of fines contents was generated. Conventional triaxial (without suffusion) and suffusion (without triaxial compression) tests were also conducted as comparisons. By taking full advantage of the dynamic mesh technique, this coupled method was able to capture not only the deformation of the soil sample but also the evolutions of pores and microstructures. Simulation results indicate that both the eroded mass and the fluid velocity are significantly increased under the condition of triaxial compression, which can be attributed to the deformation of the pores, the downward movement of the loading wall, and the increased hydraulic gradient during the suffusion. In addition, sensitivity analysis indicates that the percentage of eroded mass increases with the increase of hydraulic head, loading rate, and fines content.

关键词： Triaxial compression Suffusion discrete-element method Dynamic fluid mesh Gap-graded soil

来源：评论

学校读者我要写书评

暂无评论

DEM Exploration of Stress Transmission and Small Strain Behavior of Rubber Sand Mixtures

引用

JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING 2025年第5期151卷

作者： Liu, Deyun Yin, Zhen-Yu O'Sullivan, Catherine Hong Kong Polytech Univ Dept Civil & Environm Engn Hung Hom 1 Yuk Choi Rd Hong Kong Peoples R China Hong Kong Univ Sci & Technol Dept Civil & Environm Engn Clear Water Bay Hong Kong Peoples R China Imperial Coll London Particulate Soil Mech 501 Skempton BldgSouth Kensington Campus London SW7 2BX England

This paper presents a method to create rubber clumps without significant volume loss within the framework of the discrete-element method (DEM), enhancing the understanding of particle-scale stress transmission and small strain behavior of sand-rubber mixtures. Extensive calibrations were conducted, including the compressive response of individual pure rubber clumps, the small strain stiffness and the shear behavior of pure rubber specimens. These calibrations aimed to accurately capture the key characteristics of rubber materials, including their deformability. The calibrated model was then used to study the mechanics of sand-rubber mixtures. The simulation data indicated a higher coordination number for rubber clumps, a result of their greater deformability and significant sensitivity to stress levels in comparison with sand grains. The research has further demonstrated that the proportion of the overall stress transferred by the rubber remained below its volumetric content, highlighting its significant sensitivity to stress and density levels, which are characteristics not significant in sand particles. Additionally, the small strain stiffness values of sand-rubber mixtures decrease with increasing rubber contents, reflecting the negligible contributions of rubber materials on small-strain stiffness. This observation supports the validity of refined state variables that exclude rubber materials when characterizing the small-strain behavior of sand-rubber mixtures. While this research is fundamental, the data presented herein can be useful to engineers working on embedding waste materials such as granular rubber in engineered fill.

关键词： discrete-element method Sand-rubber mixtures Small-strain stiffness Stress transmission

来源：评论

学校读者我要写书评

暂无评论

An evaluation of the explicit finite-element method approach for modelling dense flows of discrete grains in a Couette shear cell

引用

PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY 2008年第J6期222卷 715-723页

作者： Kabir, M. A. Jasti, V. K. Higgs, C. F., III Lovell, M. R. Univ Pittsburgh Sch Engn Dept Mech Engn Pittsburgh PA 15260 USA Carnegie Mellon Univ Dept Mech Engn Pittsburgh PA 15213 USA

Granular flows are complex materials that are composed of discrete solid particles that can display gaseous, liquid, and/or solid behaviour under various conditions. Consequently, tribologists have studied them for their ability to carry loads and/or accommodate sliding surface velocities. Because of the highly non-linear behaviour of granular materials, their behaviour is difficult to predict. One new modelling approach that holds promise in simulating the behaviour of these particulate materials is the explicit finite-element method (FEM). The explicit FEM is a computational modelling approach capable of capturing dynamic, transient events, such as collisions and particle-particle interactions of grains in granular flows. This paper presents an explicit FEM simulation of a dense flow of steel particles in a rough gravity-free Couette shear cell with no externally applied load. Parametric tests of this cell are also carried out by varying the height of the shear cell and the types of known granular materials sheared in the cell. Subsequently, a final evaluation of the explicit FEM approach is conducted by simulating a dense flow of sheared titanium oxide (TiO2) powder in the shear cell and comparing it to a similar simulation done using the discrete-element method (DEM) approach. In this comparison, the velocity of the flow in the DEM cell is larger, whereas the FEM and DEM solid fraction distributions are almost identical in the core regions of the shear cells. The merits of the FEM and DEM approaches are presented in light of the results shown in this work.

关键词： explicit finite-element method granular flow discrete-element method granular lubrication

来源：评论

学校读者我要写书评

暂无评论

Shear Mechanical Properties of Rock Joints Under Non-Uniform Load Based on DEM

引用

APPLIED SCIENCES-BASEL 2025年第8期15卷 4257-4257页

作者： Liu, Hongwei Zhang, Xing Lin, Hang Chen, Yifan Yang, Chaoyi Ou, Ke Cent South Univ Sch Resources & Safety Engn Changsha 410083 Peoples R China Yunnan Diqing Nonferrous Met Co Ltd Shangri La 674400 Peoples R China China Railway 5 Engn Grp Co Ltd Guiyang 550003 Guizhou Peoples R China

Previous joint test studies have mainly been conducted under the condition of uniformly distributed loads, but in engineering, overlying loads are often non-uniformly distributed. It is necessary to investigate the shear mechanical properties of joints under non-uniform loads. This paper establishes three typical mechanical models: far-field concentration (FFC), near-field concentration (NFC), and focus on center (FOC). Direct shear test simulations using the DEM software PFC reveal that the location of load concentration affects main shear parameters. The closer the load concentration is to the far end along the shear direction, the greater the deformation of rock mass during failure is, the higher the proportion of shear cracks is, and the greater the strength and energy required for failure are. Compared to a uniformly distributed load (UD) condition, FOC shows similar mechanical properties;NFC yields inferior outcomes, while FFC results in superior mechanical performance compared to UD. By utilizing machine learning, five prediction models for non-uniform load shear strength are developed, with the Genetic-XGBoost algorithm demonstrating the highest accuracy. Weight calculation results indicate that load distribution form is the most critical factor influencing shear strength.

关键词： joint non-uniform load discrete-element method crack evolution energy evolution machine learning

来源：评论

学校读者我要写书评

暂无评论

Hierarchical Modeling method for DEM Simulation and Its Application in Soil-Pile-Cap Interaction and Impact Case

引用

INTERNATIONAL JOURNAL OF GEOMECHANICS 2019年第7期19卷 4019076.1-4019076.11页

作者： Zhao, Honghua Zhang, Jin Qiu, Peng Ji, Shunying Dalian Univ Technol Int Res Ctr Computat Mech Dept Engn Mech State Key Lab Struct Anal Ind Equipment Dalian 116023 Liaoning Peoples R China

By developing a hierarchical modeling method, using discrete element analysis software PFC3D, a discrete-element method (DEM) model can be built and solved more efficiently. In this method, smaller particles are used for the concerned part, medium-sized particles are used in the transition zone, and larger particles are used for the part that is close to the model boundary. By adjusting the micromechanical parameters of the particles through simulated triaxial tests, the macroscopic mechanical properties of the soils constituted by different-sized particles are kept consistent. This method can be applied to study the soil-structure interaction problems with the DEM method by saving computation cost. The proposed method is verified by a two-dimensional (2D) simulation of a laboratory pile load test. This method is then further applied to investigate the pile-soil-cap interaction problem focusing on the pile cap effects. A geohazard-related impact case is also analyzed using this method.

关键词： discrete-element method Pile foundation Hierarchical modeling Pile cap effects Impact

来源：评论

学校读者我要写书评

暂无评论

Time step criterions for nonlinear dense packed granular materials in time-driven method simulations

引用

POWDER TECHNOLOGY 2014年 253卷 80-88页

作者： Huang, Yrjo J. Nydal, Ole Jorgen Yao, Baodian Fudan Univ Dept Mech & Engn Sci Shanghai 200433 Peoples R China Norwegian Univ Sci & Technol Dept Energy & Proc Engn N-7491 Trondheim Norway Shanghai Univ Engn Sci Sch Mat Engn Shanghai 201620 Peoples R China

discrete-element method (DEM) is a powerful tool for simulations of granular materials. As one branch of DEM, time-driven method (TDM) is suitable for the materials in dense phase. Time step is an important parameter in TDM simulations, which decides the CPU time and the computational accuracy. When a granular system under gravity is deep and nonlinear stress-strain relationship is used to model the particle-particle interaction, some current time step models are not applicable anymore, because the nature frequency of a particle is affected by its boundary conditions. To amend this shortage, a new time step criterion is presented in this paper, which involves the effect from the depth of the system due to gravity. Between this new criterion and that based on Rayleigh time, the smaller one should be the upper limitation of time step in TDM simulations. (C) 2013 Elsevier B.V. All rights reserved.

关键词： discrete-element method Time step Dense packed granular material

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：