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Application of the expanded distinct element method for the study of crack growth in rock-like materials

Lei YANG, Yujing JIANG, Bo LI, Shucai LI, Yang GAO

《结构与土木工程前沿(英文)》 2012年 第6卷 第2期   页码 121-131 doi: 10.1007/s11709-012-0151-0

摘要: The expanded distinct element method (EDEM) was used to investigate the crack growth in rock-like materials under uniaxial compression. The tensile-shear failure criterion and the Griffith failure criterion were implanted into the EDEM to determine the initiation and propagation of pre-existing cracks, respectively. Uniaxial compression experiments were also performed with the artificial rock-like samples to verify the validity of the EDEM. Simulation results indicated that the EDEM model with the tensile-shear failure criterion has strong capabilities for modeling the growth of pre-existing cracks, and model results have strong agreement with the failure and mechanical properties of experimental samples. The EDEM model with the Griffith failure criterion can only simulate the splitting failure of samples due to tensile stresses and is incapable of providing a comprehensive interpretation for the overall failure of rock masses. Research results demonstrated that sample failure primarily resulted from the growth of single cracks (in the form of tensile wing cracks and shear secondary cracks) and the coalescence of two cracks due to the growth of wing cracks in the rock bridge zone. Additionally, the inclination angle of the pre-existing crack clearly influences the final failure pattern of the samples.

关键词: expanded distinct element method (EDEM)     crack growth     rock-like material     tensile-shear failure criterion     Griffith failure criterion     mechanical and failure behavior    

Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1372-1389 doi: 10.1007/s11709-021-0772-2

摘要: Acoustic emission and digital image correlation were used to study the spatiotemporal evolution characteristics of crack extension of soft and hard composite laminated rock masses (SHCLRM) containing double fissures under uniaxial compression. The effects of different rock combination methods and prefabricated fissures with different orientations on mechanical properties and crack coalescence patterns were analyzed. The characteristics of the acoustic emission source location distribution, and frequency changes of the crack evolution process were also investigated. The test results show that the damage mode of SHCLRM is related to the combination mode of rock layers and the orientation of fractures. Hard layers predominantly produce tensile cracks; soft layers produce shear cracks. The first crack always sprouts at the tip or middle of prefabricated fractures in hard layers. The acoustic emission signal of SHCLRM with double fractures has clear stage characteristics, and the state of crack development can be inferred from this signal to provide early warning for rock fracture instability. This study can provide a reference for the assessment of the fracture development status between adjacent roadways in SHCLRM in underground mines, as well as in roadway layout and support.

关键词: soft−hard composite layered rock mass     double cracks     crack evolution     acoustic emission     digital image correlation    

地震波荷载作用下类岩石试样波形传播和裂纹扩展数值模拟研究 Article

张晓平, 张旗, 刘泉声, 肖锐铧

《工程(英文)》 2022年 第17卷 第10期   页码 140-150 doi: 10.1016/j.eng.2021.09.023

摘要:

地震之后伴随的余震在地震诱发滑坡灾害中起着重要作用。主震中已对岩体造成了不同程度的损伤,这使得余震过程中岩体裂纹进一步发展和相互交互贯通过程更复杂。为了探究地震波荷载对类岩石试样破裂失稳过程的影响,通过采用基于颗粒元黏结模型(bonded-particle model, BPM)的数值方法,研究了在两个正交方向上循环地震波加载作用下的波传播规律和裂纹扩展过程。结果表明,由于计算试样尺寸(76 mm × 152 mm)远小于地震波纵波波长,试样内未观察到波的透射和反射现象;加载产生的裂纹均为微张拉裂纹,重复轴向地震波加载不能使微张拉裂纹进一步扩展;只有当加载方向由轴向变为侧向,再由侧向变为轴向时,裂纹才会进一步扩展并最终导致试样破坏。本文揭示了在地震波反射作用及余震作用下,大量滑坡灾害发生的内在机理。

关键词: 地震波     循环荷载     裂纹扩展     黏结模型    

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

Peter TSCHERNUTTER

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 63-70 doi: 10.1007/s11709-010-0016-3

摘要: This paper demonstrates the difficulties in determining the relevant material parameters for a valuation of the deformation behavior of the up- and downstream dam shell by means of an embankment dam of medium height. Laboratory as well as field tests on solid rock-fill material were performed before the beginning of construction. During the construction the properties of the available rock-fill changed from solid to soft materials. This gave rise to the necessity of adjusting the dam design of the downstream dam shoulder. Several times higher dam settlements as well as significant differential settlements between the up- and downstream dam shell were observed during construction and operation. Apart from this situation, the dam has been operated for nearly 20 years and the behavior of the water barrier has been very good.

关键词: embankment dam     bituminous concrete membrane     rock-fill material properties     deformation behavior    

Mechanical properties of rock materials with related to mineralogical characteristics and grain size

Wenjuan SUN, Linbing WANG, Yaqiong WANG

《结构与土木工程前沿(英文)》 2017年 第11卷 第3期   页码 322-328 doi: 10.1007/s11709-017-0387-9

摘要: Mechanical properties of rock materials are related to textural characteristics. The relationships between mechanical properties and textural characteristics have been extensively investigated for differently types of rocks through experimental tests. Based on the experimental test data, single- and multiple- variant regression analyses are conducted among mechanical properties and textural characteristics. Textural characteristics of rock materials are influenced by the following factors: mineral composition, size, shape, and spatial distribution of mineral grains, porosity, and inherent microcracks. This study focuses on the first two: mineral composition and grain size. ? This study comprehensively summarizes the regression equations between mechanical properties and mineral content and the regression equations between mechanical properties and grain size. Further research directions are suggested at the end of this study.

关键词: Mechanical properties     rock material     texture     mineral characteristics    

胶结颗粒料坝——环境友好的新坝型

贾金生, Michel Lino, 金峰, 郑璀莹

《工程(英文)》 2016年 第2卷 第4期   页码 490-497 doi: 10.1016/J.ENG.2016.04.003

摘要:

笔者于2009年提出了胶结颗粒料坝的概念,目的在于修建更安全、更经济的环境友好的大坝。该坝型包括胶结砂砾石坝(曾用名胶凝砂砾石坝)、堆石混凝土坝(或胶结堆石坝)和胶结土坝。本文基于研究和实践,进一步阐述了胶结颗粒料坝的概念和原则,介绍了胶结砂砾石坝、堆石混凝土坝和胶结土坝的新进展。

关键词: 胶结颗粒料坝     胶结砂砾石坝     堆石混凝土坝     胶结堆石坝     胶结土坝     材料特性    

Mercury removal from aqueous solution using petal-like MoS2

Ragini Pirarath, Palani Shivashanmugam, Asad Syed, Abdallah M. Elgorban, Sambandam Anandan, Muthupandian Ashokkumar

《环境科学与工程前沿(英文)》 2021年 第15卷 第1期 doi: 10.1007/s11783-020-1307-0

摘要: Abstract • Synthesized few-layered MoS2 nanosheets via surfactant-assisted hydrothermal method. • Synthesized MoS2 nanosheets show petal-like morphology. • Adsorbent showed 93% of mercury removal efficiency. • The adsorption of mercury is attributed to negative zeta potential (-21.8 mV). Recently, different nanomaterial-based adsorbents have received greater attention for the removal of environmental pollutants, specifically heavy metals from aqueous media. In this work, we synthesized few-layered MoS2 nanosheets via a surfactant-assisted hydrothermal method and utilized them as an efficient adsorbent for the removal of mercury from aqueous media. The synthesized MoS2 nanosheets showed petal-like morphology as confirmed by scanning electron microscope and high-resolution transmission electron microscopic analysis. The average thickness of the nanosheets is found to be about 57 nm. Possessing high stability and negative zeta potential makes this material suitable for efficient adsorption of mercury from aqueous media. The adsorption efficiency of the adsorbent was investigated as a function of pH, contact time and adsorbent dose. The kinetics of adsorption and reusability potential of the adsorbent were also performed. A pseudo-second-order kinetics for mercury adsorption was observed. As prepared MoS2 nanosheets showed 93% mercury removal efficiency, whereas regenerated adsorbent showed 91% and 79% removal efficiency in the respective 2nd and 3rd cycles. The adsorption capacity of the adsorbent was found to be 289 mg/g at room temperature.

关键词: Anionic surfactant     2D material     MoS2 nanosheets     Mercury removal     Adsorption capacity    

Computational methods for fracture in rock: a review and recent advances

Ali JENABIDEHKORDI

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 273-287 doi: 10.1007/s11709-018-0459-5

摘要: We present an overview of the most popular state-of-the-art computational methods available for modelling fracture in rock. The summarized numerical methods can be classified into three categories: Continuum Based Methods, Discrete Crack Approaches, and Block-Based Methods. We will not only provide an extensive review of those methods which can be found elsewhere but particularly address their potential in modelling fracture in rock mechanics and geotechnical engineering. In this context, we will discuss their key applications, assumptions, and limitations. Furthermore, we also address ‘general’ difficulties that may arise for simulating fracture in rock and fractured rock. This review will conclude with some final remarks and future challenges.

关键词: numerical modelling     method development     rock mechanics     fractured rock     rock fracturing    

Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0035-5

摘要: Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and power cone programming

关键词: finite element power     stability rock escarpment    

Distinct immune escape and microenvironment between RG-like and pri-OPC-like glioma revealed by single-cell

《医学前沿(英文)》 doi: 10.1007/s11684-023-1017-7

摘要: The association of neurogenesis and gliogenesis with glioma remains unclear. By conducting single-cell RNA-seq analyses on 26 gliomas, we reported their classification into primitive oligodendrocyte precursor cell (pri-OPC)-like and radial glia (RG)-like tumors and validated it in a public cohort and TCGA glioma. The RG-like tumors exhibited wild-type isocitrate dehydrogenase and tended to carry EGFR mutations, and the pri-OPC-like ones were prone to carrying TP53 mutations. Tumor subclones only in pri-OPC-like tumors showed substantially down-regulated MHC-I genes, suggesting their distinct immune evasion programs. Furthermore, the two subgroups appeared to extensively modulate glioma-infiltrating lymphocytes in distinct manners. Some specific genes not expressed in normal immune cells were found in glioma-infiltrating lymphocytes. For example, glial/glioma stem cell markers OLIG1/PTPRZ1 and B cell-specific receptors IGLC2/IGKC were expressed in pri-OPC-like and RG-like glioma-infiltrating lymphocytes, respectively. Their expression was positively correlated with those of immune checkpoint genes (e.g., LGALS3) and poor survivals as validated by the increased expression of LGALS3 upon IGKC overexpression in Jurkat cells. This finding indicated a potential inhibitory role in tumor-infiltrating lymphocytes and could provide a new way of cancer immune evasion.

关键词: single-cell RNA-seq     glioma     radial glia     primitive oligodendrocyte precursor cell     immune escape    

Self-sacrificial templating synthesis of flower-like nickel phyllosilicates and its application as high-performance

《化学科学与工程前沿(英文)》 2022年 第16卷 第4期   页码 484-497 doi: 10.1007/s11705-021-2074-6

摘要: The nanocomposites of flower-like nickel phyllosilicate particles incorporated into epoxy resin were fabricated via an in-situ mixing process. The flower-like nickel phyllosilicate particles were firstly synthesized using a mild self-sacrificial templating method, and the morphology and lamellar structure were examined carefully. Several properties of mechanical, thermal and tribological responses of epoxy nanocomposites were performed. It was demonstrated that adequate flower-like nickel phyllosilicate particles dispersed well in the matrix, and the nanocomposites displayed enhanced tensile strength and elastic modulus but decreased elongation at break as expected. In addition, friction coefficient and wear rate were increased first and then decreased along with the particle content, and showed the lowest values at a mass fraction of 5%. Nevertheless, the incorporated flower-like nickel phyllosilicate particles resulted in the continuously increasing thermal stability of epoxy resin (EP) nanocomposites. This study revealed the giant potential of flower-like particles in preparing high-quality EP nanocomposites.

关键词: nickel phyllosilicate     flow-like structure     mechanical property     thermal stability     tribological performance    

Aspects of rock permeability

Lianyang ZHANG

《结构与土木工程前沿(英文)》 2013年 第7卷 第2期   页码 102-116 doi: 10.1007/s11709-013-0201-2

摘要: Effective evaluation of rock permeability is required in different energy, engineering and environmental projects. Although much research has been conducted on rock permeability, it is still one of the most difficult tasks for practicing rock engineers to accurately determine rock permeability. Based on a comprehensive literature review, this paper outlines the key aspects of rock permeability by presenting the representative values of the permeability of different rocks, describing the empirical and semi-empirical correlations for estimating the permeability of rocks, and discussing the main factors affecting the permeability of rocks. The factors discussed include stress, depth, temperature, and discontinuity intensity and aperture. This paper also highlights the scale effect on rock permeability, interconnectivity of discontinuities, and anisotropy of rock permeability. This paper provides the fundamental and essential information required for effective evaluation of rock permeability.

关键词: rock     permeability     discontinuity     stress     temperature     scale effect     anisotropy    

Toll-like receptors in innate immunity and infectious diseases

Min-Hao WU, Ping ZHANG, Xi HUANG,

《医学前沿(英文)》 2010年 第4卷 第4期   页码 385-393 doi: 10.1007/s11684-010-0600-x

摘要: The protective ability of host defense system is largely dependent on germ-line encoded pattern-recognition receptors (PRRs). These PRRs respond to a variety of exogenous pathogens or endogenous danger signals, by recognizing some highly conserved structures such as pathogen-associated molecular patterns (PAMPs) and danger/damage associated molecular patterns (DAMPs). The most studied PRRs are Toll-like receptors (TLRs). Activation of TLRs triggers production of inflammatory cytokines and type I interferons (IFNs) via myeloid differentiation primary response gene 88 (MyD88)-dependent or-independent signaling respectively, thereby modulating innate and adaptive immunity, as well as inflammatory responses. This review introduces the classification, structure, and specific ligands of TLRs, and focuses on their signal pathways and biological activities, as well as clinical relevance. These studies of TLRs in the innate immune system have implications for the prevention and treatment of a variety of infectious diseases, including tuberculosis (TB), microbial keratitis, and hepatitis B and C.

关键词: Toll-like receptors     innate immunity     infectious disease     inflammation    

interface adhesion factor on the bearing capacity of strip footing placed on cohesive soil overlying rock

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1494-1503 doi: 10.1007/s11709-021-0768-y

摘要: The problem related to bearing capacity of footing either on pure soil or on pure rock mass has been investigated over the years. Currently, no study deals with the bearing capacity of strip footing on a cohesive soil layer overlying rock mass. Therefore, by implementing the lower bound finite element limit analysis in conjunction with the second-order cone programming and the power cone programming, the ultimate bearing capacity of a strip footing located on a cohesive soil overlying rock mass is determined in this study. By considering the different values of interface adhesion factor (αcr) between the cohesive soil and rock mass, the ultimate bearing capacity of strip footing is expressed in terms of influence factor (If) for different values of cohesive soil layer cover ratio (Tcs/B). The failure of cohesive soil is modeled by using Mohr−Coulomb yield criterion, whereas Generalized Hoek−Brown yield criterion is utilized to model the rock mass at failure. The variations ofIf with different magnitudes of αcr are studied by considering the influence of the rock mass strength parameters of beneath rock mass layer. To examine stress distribution at different depths, failure patterns are also plotted.

关键词: bearing capacity     soil-rock interface     Hoek−Brown yield criterion     plasticity     limit analysis    

Dispersion of “guava-like” silica/polyacrylate nanocomposite particles in polyacrylate matrix

QI Dongming, YANG Lei, WU Minghua, SHAO Jianzhong, BAO Yongzhong

《化学科学与工程前沿(英文)》 2008年 第2卷 第2期   页码 127-134 doi: 10.1007/s11705-008-0033-0

摘要: A series of “guava-like” silica/polyacrylate nanocomposite particles with close silica content and different grafting degrees were prepared via mini-emulsion polymerization using 3-(trimethoxysilyl)propyl methacrylate (TSPM) modified silica/acrylate dispersion. The silica/polyacrylate composite particles were melt-mixed with unfilled polyacrylate (PA) resin to prepare corresponding silica/polyacrylate molded composites and the dispersion mechanism of these silica particles from the “guava-like” composite particles into polyacrylate matrix was studied. It was calculated that about 110 silica particles were accumulated in the bulk of every silica/polyacrylate composite latex particle. Both the solubility tests of silica/polyacrylate composite latex particles in tetrahydrofuran (THF) and the section transmission electron microscope (TEM) micrographs of silica/polyacrylate molded composites indicated that the grafting degree of silica particles played a crucial role in the dispersion of silica/polyacrylate composite particles into the polyacrylate matrix. When the grafting degree of polyacrylate onto silica was in a moderate range (ca. 20%–70%), almost all of silica particles in these “guava-like” composite particles were dispersed into the polyacrylate matrix in a primary-particle-level. However, at a lower grafting degree, massive silica aggregations were found in molded composites because of the lack of steric protection. At a greater grafting degree (i.e., 200%), a cross-linked network was formed in the silica/polyacrylate composite particles, which prevented the dispersion of composite particles in THF and polyacrylate matrix as primary particles.

关键词: silica/polyacrylate composite     cross-linked network     –70     guava-like     TEM    

标题 作者 时间 类型 操作

Application of the expanded distinct element method for the study of crack growth in rock-like materials

Lei YANG, Yujing JIANG, Bo LI, Shucai LI, Yang GAO

期刊论文

Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

期刊论文

地震波荷载作用下类岩石试样波形传播和裂纹扩展数值模拟研究

张晓平, 张旗, 刘泉声, 肖锐铧

期刊论文

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

Peter TSCHERNUTTER

期刊论文

Mechanical properties of rock materials with related to mineralogical characteristics and grain size

Wenjuan SUN, Linbing WANG, Yaqiong WANG

期刊论文

胶结颗粒料坝——环境友好的新坝型

贾金生, Michel Lino, 金峰, 郑璀莹

期刊论文

Mercury removal from aqueous solution using petal-like MoS2

Ragini Pirarath, Palani Shivashanmugam, Asad Syed, Abdallah M. Elgorban, Sambandam Anandan, Muthupandian Ashokkumar

期刊论文

Computational methods for fracture in rock: a review and recent advances

Ali JENABIDEHKORDI

期刊论文

Correction to: Effect of undercut on the lower bound stability of vertical rock escarpment using finite

期刊论文

Distinct immune escape and microenvironment between RG-like and pri-OPC-like glioma revealed by single-cell

期刊论文

Self-sacrificial templating synthesis of flower-like nickel phyllosilicates and its application as high-performance

期刊论文

Aspects of rock permeability

Lianyang ZHANG

期刊论文

Toll-like receptors in innate immunity and infectious diseases

Min-Hao WU, Ping ZHANG, Xi HUANG,

期刊论文

interface adhesion factor on the bearing capacity of strip footing placed on cohesive soil overlying rock

期刊论文

Dispersion of “guava-like” silica/polyacrylate nanocomposite particles in polyacrylate matrix

QI Dongming, YANG Lei, WU Minghua, SHAO Jianzhong, BAO Yongzhong

期刊论文