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Study on disc cutter chipping of TBM based on field data and particle flow code simulation

Underground Space 2023年第2期9卷 122-139页

作者： Yadong Xue Yongqiang Fan Xing Li Kai Shen Jiaxuan Wang Key Laboratory of Geotechnical and Underground Engineering of Education Ministry Tongji UniversityShanghai 200092China Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China China State Construction Silkroad Construction Investment Group Co. LTDXi’an 710075China School of Civil Engineering Central South UniversityChangsha 410075China

Using tunnel boring machines to excavate high-strength intact rock masses is becoming more common.Due to the interactions between disc cutters and rocks,abnormal wear of disc cutters,especially cutter chipping,has become a common phenomenon.Existing research has mainly focused on normal wear of disc cutters without addressing abnormal wear cases.This study used the disc cutter consumption data of a tunnel project in China to investigate the abovementioned problem based on field research.According to the fail-ure patterns and fracture surface characteristics,the cutter chipping patterns were mainly categorized into four types:granule chipping,patch chipping,primary collapse,and secondary collapse.To further simulate the evolution of disc cutter chipping,based on the linear plastic bond model,a new contact model called the modified plastic bond(MPB)model was proposed to solve the metal simulation prob-lem in particle flow code software.To this end,a set of uniaxial tensile and compressive tests were initially conducted to verify the applicability of the MPB model.Then,a series of three-dimensional rock-cutting simulation tests were conducted to reflect the evolu-tionary processes involved in each type of cutter chipping.The cutter chipping mechanism and morphological characteristics were clas-sified and summarized in detail.The results revealed that the cutting speed and penetration growth led to a rising trend in the probability and intensity of the cutter chipping.The presence of initial defects also induced an adverse effect on the service life of the cutter.The results indicated suitable working conditions for the cutter and suggested ways to control tunneling parameters and avoid frequent cutter chipping cases.

关键词： Tunnel boring machine Disc cutter Cutter chipping particle flow code Modified plastic bond model

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Microdamage study of granite under thermomechanical coupling based on the particle flow code

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Frontiers of Structural and Civil Engineering 2023年第9期17卷 1413-1427页

作者： Chong SHI Yiping ZHANG Yulong ZHANG Xiao CHEN Junxiong YANG Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjing 210098China College of Civil and Transportation Engineering Hohai UniversityNanjing 210098China Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines College of Resources and Civil EngineeringNortheastern UniversityShenyang 110819China Department of Civil and Mineral Engineering University of TorontoToronto M5S1A1Canada

The thermomechanical coupling of rocks refers to the interaction between the mechanical and thermodynamic behaviors of rocks induced by temperature changes.The study of this coupling interaction is essential for understanding the mechanical and thermodynamic properties of the surrounding rocks in underground engineering.In this study,an improved temperature-dependent linear parallel bond model is introduced under the framework of a particle flow simulation.A series of numerical thermomechanical coupling tests are then conducted to calibrate the micro-parameters of the proposed model by considering the mechanical behavior of the rock under different thermomechanical loadings.Good agreement between the numerical results and experimental data are obtained,particularly in terms of the compression,tension,and elastic responses of granite.With this improved model,the thermodynamic response and underlying cracking behavior of a deep-buried tunnel under different thermal loading conditions are investigated and discussed in detail.

关键词： thermomechanical coupling effect granite improved linear parallel bond model thermal property particle flow code

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particle flow code simulation of intact and fissured granitic rock samples

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第5期12卷 960-974页

作者： Uxía Castro-Filgueira Leandro R.Alejano Diego Mas Ivars Department of Natural Resources and Environmental Engineering University of VigoVigoSpain Department of Geology and Geological Engineering Colorado School of MinesGoldenCOUSA Swedish Nuclear Fuel and Waste Management Company(SKB) StockholmSweden Division of Soil and Rock Mechanics Royal Institute of Technology(KTH)StockholmSweden

This study presents a calibration process of three-dimensional particle flow code(PFC3D)simulation of intact and fissured granite samples.First,laboratory stressestrain response from triaxial testing of intact and fissured granite samples is recalled.Then,PFC3D is introduced,with focus on the bonded particle models(BPM).After that,we present previous studies where intact rock is simulated by means of flatjoint approaches,and how improved accuracy was gained with the help of parametric studies.Then,models of the pre-fissured rock specimens were generated,including modeled fissures in the form of“smooth joint”type contacts.Finally,triaxial testing simulations of 1 t 2 and 2 t 3 jointed rock specimens were performed.Results show that both elastic behavior and the peak strength levels are closely matched,without any additional fine tuning of micro-mechanical parameters.Concerning the postfailure behavior,models reproduce the trends of decreasing dilation with increasing confinement and plasticity.However,the dilation values simulated are larger than those observed in practice.This is attributed to the difficulty in modeling some phenomena of fissured rock behaviors,such as rock piece corner crushing with dust production and interactions between newly formed shear bands or axial splitting cracks with pre-existing joints.

关键词： Numerical methods Artificially fissured samples Rock mass behavior particle flow code Parallel bond Flat-joint Smooth-joint

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Crack mechanism of ground fissures in loess layer of Fenwei Basin, China

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Journal of Mountain Science 2024年第5期21卷 1683-1696页

作者： LI Cong LU Quanzhong WANG Feiyong LUO Wenchao XU Qiang School of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China Key Laboratory of Western Mineral Resources and Geological Engineering Ministry of EducationXi’an 710054China Observation and Research Station of Ground Fissure and Land Subsidence Ministry of Natural ResourcesXi’an 710054China School of Engineering and Technology China University of GeosciencesBeijing 100083China

The Fenwei Basin, covered by loess, experiences severe ground fissure disasters. These disasters disrupt the continuity of the loess and pose significant threats to engineering construction safety along transportation routes. Nevertheless, the crack characteristics and the influence zone of ground fissures in the loess layer remain inadequately investigated. To effectively prevent and control ground fissure disasters, physical model tests and the PFC(particle flow code) numerical simulation method are used to investigate the crack mechanism of buried ground fissures in the loess layer. The results show that there are two main cracks in the layer profile, which have a Y-shape morphology. As the dip angle of the preset cracks increased from 60° to 90°, the main deformation zone at the surface gradually shifted towards the footwall. The process of crack propagation from depth to surface is divided into five stages. Additionally, the results confirm the accuracy of the width of the rupture zone d2in the footwall calculated by the cantilever beam theory. These findings can offer theoretical guidance for determining the avoidance distance of ground fissures in loess regions, as well as for implementing disaster prevention and corresponding control measures for various stages of buried ground fissure propagation.

关键词： Ground fissure Fenwei Basin Physical model test particle flow code Crack propagation

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Mechanical Behavior of Polyurethane Polymer Materials under Triaxial Cyclic Loading:A particle flow code Approach

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Journal of Wuhan University of Technology(Materials Science) 2018年第4期33卷 980-986页

作者：刘恒 WANG Fuming 石明生 TIAN Wenling School of Water Conservancy and Environment Zhengzhou University School of Civil and Transportation Engineering Henan University of Urban Construction State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining & TechnologyXuzhou

Polyurethane polymer grouting materials were studied with conventional triaxial tests via the particle flow code in two dimensions（PFC^（2D）） method, and the simulation results agreed with the experimental data. The particle flow code method can simulate the mechanical properties of the polymer. The triaxial cyclic loading tests of the polymer material under different confining pressures were carried out via PFC^（2D） to analyze its mechanical performance. The PFC^（2D） simulation results show that the value of the elastic modulus of the polymer decreases slowly at first and fluctuated within a narrow range near the value of the peak strength; the cumulative plastic strain increases slowly at first and then increases rapidly; the peak strength and elastic modulus of polymer increase with the confining pressure; the PFC^（2D） method can be used to quantitatively evaluate the damage behavior of the polymer material and estimate the fatigue life of the materials under fatigue load based on the number and the location of micro-cracks. Thus, the PFC^（2D） method is an effective tool to study polymers.

关键词： polymer particle flow code cyclic loading elastic modulus micro-cracks axial strain

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Calibration method of mesoscopic parameter in sandy cobble soil triaxial test based on PFC3D

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Frontiers of Structural and Civil Engineering 2023年第12期17卷 1924-1933页

作者： Pengfei LI Xiaopu CUI Yingjie WEI Junwei XIA Xinyu WANG Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing 100124China China Railway 14th Bureau Group Co. Ltd.Jinan 250014China China Railway 19 Bureau Group Rail Traffic Engineering Co. Ltd.Beijing 101399China School of Civil Engineering Henan Polytechnic UniversityJiaozuo 454000China

This paper presents a rapid and effective calibration method of mesoscopic parameters of a threedimensional particle flow code(PFC3D)model for sandy cobble soil.The method is based on a series of numerical tests and takes into account the significant influence of mesoscopic parameters on macroscopic parameters.First,numerical simulations are conducted,with five implementation steps.Then,the multi-factor analysis of variance method is used to analyze the experimental results,the mesoscopic parameters with significant influence on the macroscopic response are singled out,and their linear relations to macroscopic responses are estimated by multiple linear regression.Finally,the parameter calibration problem is transformed into a multi-objective function optimization problem.Numerical simulation results are in good agreement with laboratory results both qualitatively and quantitatively.The results of this study can provide a basis for the calibration of microscopic parameters for the investigation of sandy cobble soil mechanical behavior.

关键词： sandy cobble soil particle flow code orthogonal experiment regression analysis multi-objective optimization calibration

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Study of seismic response of colluvium accumulation slope by particle flow code

Study of seismic response of colluvium accumulation slope by...

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中国科学院地质与地球物理研究所第十届(2010年度)学...

作者： Jianming He·Xiao Li·Shouding Li·Yueping Yin·Haitao Qian Key Laboratory of Engineering Geomechanics,Institute of Geology and Geophysics,Chinese Academy of Sciences, Beijing 100029,People’s Republic of China China Geological Survey,Beijing 100037, People’s Republic of China Institute of Crustal Dynamics,China Earthquake Administration, Beijing 100085,People’s Republic of China

Colluvium accumulation slopes(CAS)are widely distributed in Sichuan Province of China,especially in the regions with intense earthquake histories.These kinds of accumulations show obvious discontinuous and heterogeneous characteristics,to which the discrete element method (DEM)for discontinuous material is more suitably applied. Wenchuan earthquake with a magnitude of 8.0,caused a large number of debris flows or landslides in the colluvium formations, which are densely distributed in the quake-hit region in Sichuan province.The dynamic response of CAS is a key problem for study of stability of these kinds of slope.In this paper,PFC(particle flow code)from Itasca based on DEM is used for modeling the dynamic response of the colluvium accumulations and some typical models were built according to the geological investigations carried out in the epicentral area.Horizontal shearing waveforms of WenChuan earthquake were input into the model for the study of the dynamic response of overlying colluvium accumulation and bedrock. The modeling results of different models under the same seismic conditions are described and analyzed at the end of the paper.

关键词： Colluvium accumulation slope（CAS） Dynamic response particle flow code Discontinuous characteristics

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Discrete element simulation of crushable rockfill materials

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Water Science and Engineering 2013年第2期6卷 215-229页

作者： Lei SHAO Shi-chun CHI Liang-jing ZHOU Yu-zan WANG Faculty of Infrastructure Engineering Dalian University of Technology Hydrochina Chengdu Engineering Corporation Changjiang Institute of Survey Planning Design and Research Changjiang Water Resources Commission

A discrete element method was used to study the evolution of particle crushing in a rockfill sample subjected to triaxial shear. A simple procedure was developed to generate clusters with arbitrary shapes, which resembled real rockfill particles. A theoretical method was developed to define the failure criterion for an individual particle subjected to an arbitrary set of contact forces. Then, a series of numerical tests of large-scale drained triaxial tests were conducted to simulate the behaviors of the rockfill sample. Finally, we examined the development of micro-characteristics such as particle crushing, contact characteristics, porosity, deformation, movement, and energy dissipation. The simulation results were partially compared with the laboratory experiments, and good agreement was achieved, demonstrating that the particle crushing model proposed can be used to simulate the drained triaxial test ofrockfill materials. Based on a comparison of macro behaviors of the roekfill sample and micro structures of the particles, the microscopic mechanism of the rockfill materials subjected to triaxial shear was determined qualitatively. It is shown that the crushing rate, rather than the number of crushed particles, can be used to reflect the relationship between macro- and micro-mechanical characteristics of rockfill materials. These research results further develop our understanding of the deformation mechanism of rockfill materials.

关键词： discrete element simulation triaxial shear test,＂ roclcfill material geometric construction of particles particle flow code microscopic mechanism

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Study on mechanical properties of soil-rock mixture of various compactness subjected to freeze-thaw cycles

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Research in Cold and Arid Regions 2021年第5期13卷 450-462页

作者： Zhong Zhou HaoHui Ding WenYuan Gao LinRong Xu School of Civil Engineering Central South UniversityChangshaHunan 410075China

The soil-rock mixture,a collection of soil particles and rock blocks,is inherently heterogeneous and anisotropic due to significant particle size and material strength differences.This study conducts triaxial tests on soil-rock mixture samples of various compactness subjected to varying freeze-thaw cycles.A mesoscopic simulation is carried out by particle flow code(PFC)to analyze the effects of freeze-thaw cycles on the mechanical properties of soil and rock particles.The results show that the mechanical properties of the soil-rock mixture under freeze-thaw cycles are greatly affected by the initial compaction.In general,when the degree of compaction is higher,the influence of freeze-thaw cycles on the soil-rock mixture is greater.The stress-strain curves of the samples with different compactness demonstrate strain-softening behavior.The freeze-thaw cycles greatly influence the failure strength of the samples with a higher degree of compaction but have little impact on the samples with a lower degree of compaction.On the microscopic level,during freeze-thaw cycles,the pore volume in the highly compacted sample is too small to accommodate the volume expansion from ice crystal formation,causing significant strength loss among the soil and rock particles and deterioration of the macroscopic properties of the soil-rock mixture.

关键词： soil-rock mixtures freeze-thaw cycle degree of compaction particle flow code

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The biaxial compression mechanical properties of crushed rock

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Research in Cold and Arid Regions 2013年第4期5卷 433-439页

作者： PengCheng Wang JianKun Liu Li Liu School of Civil Engineering of Beijing Jiaotong University

Crushed rock subgrade, as one of the roadbed-cooling methods, has been widely used in the Qinghai-Tibet Railway. Much attention has been paid on the cooling effect of crushed rock; however, the mechanical properties of crushed rock are somehow neglected. Based on the discrete element method, biaxial compression test condition for crushed rock is com- piled in FISH language in PFC2D, and the natural shape of crushed rock is simulated with super particle ＂cluster＂. The ef- fect of particle size, crushed rock strength and confining pressure level on overall mechanical properties of the crushed rock aggregate are respectively analyzed. Results show that crushed rock of large particle size plays an essential frame- work role, which is mainly responsible for the deformation of crushed rock aggregate. The strength of gravel has a great influence on overall mechanical properties which means that strength attenuation caused by the freeze thaw cycles cannot be ignored. The stress-strain curves can be divided into two stages including shear contraction and shear expansion at different confining pressures.

关键词： crushed rock subgrade discrete element method particle flow code mechanical property biaxial compression

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