检索结果-南通市图书馆

Laboratory Model Tests and DEM Simulations of Unloading-Induced Tunnel Failure Mechanism

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2020年第5期63卷 825-844页

作者： Abierdi Yuzhou Xiang Haiyi Zhong Xin Gu Hanlong Liu Wengang Zhang School of Hehai Chongqing Jiaotong UniversityChongqing400074China School of Civil Engineering Chongqing UniversityChongqing400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing400045China

Tunnel excavation is a complicated loading-unloading-reloading process characterized by decreased radial stresses and increased axial *** approach that considers only loading,is generally used in tunnel model ***,this approach is incapable of characterizing the unloading effects induced by excavation on surrounding rocks and hence presents radial and tangential stress paths during the failure process that are different from the actual stress state of *** paper carried out a comparative analysis using laboratory model testing and particle flow code(PFC2D)-based numerical simulation,and shed light upon the crack propagation process and,microscopic stress and force chain variations during the loading-unloading *** failure mode observed in the unloading model test is shear *** force chains are strongly correlated with the concrete fracture *** addition,the change patterns of the radial and tangential stresses of surrounding rocks in the broken region,as well as the influence of the initial stress on failure loads are *** surrounding soil of tunnel failure evolution as well as extent and shape of the damage zone during the excavation-induced unloading were also studied.

关键词： Tunnel unloading model testing particle flow model force chain

Some open problems in granular matter mechanics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2009年第5期19卷 523-529页

作者： Qicheng Sun a, Guangqian Wanga, Kaiheng Hub a Department of Hydraulic Engineering, State Key Laboratory for Hydroscience and Engineering, Tsinghua University, Beijing 100084, China b Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China Department of Hydraulic Engineering State Key Laboratory for Hydroscience and Engineering Tsinghua University Beijing 100084 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China

Granular matter is a large assemblage of solid particles, which is fundamentally different from any other type of matters, such as solid and liquid. Most models presented for granular matter are phenomenological and are only suitable for solving engineering problems. Many fundamental mechanical problems remain open. By analyzing characteristics of internal state structure, we propose that granular matter is intrinsically multiscale, i.e. microscale of particle size, mesoscale of force chain, and macroscale of the bulk of granular matter. The correlations among difference scales would be crucial. The mesoscale force chain network is determined by both particle properties and macroscopic boundary conditions. The evolution of the force the chain network contributes to macroscopic mechanical properties of granular matter. In addition, we discuss the drawbacks in simplifying contact forces in the current models, and the difficulties in analyzing the interaction of interstitial fluid in wet granular matter. As an appropriate application of granular matter, debris flow can be studied with granular matter mechanics; meanwhile, debris flow brings more challenges which certainly motivate future studies on granular matter.

关键词： Granular matter Multiscale mechanics force chain Contact mechanics Debris flow

force fluctuations in sheared granular disks

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2013年第1期7卷 46-49页

作者： Mingbo YUAN Qicheng SUN Feng JIN Shandong College of Electronic Technology Jinan 250014China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

The internal structure established within granular materials,often observed as force chains,is dominant in controlling bulk mechanical *** designed a two-dimensional Hele-Shaw cell to contain photoelastic disks,and two servos were used on the top and right boundaries *** experimentally monitored the fluctuations in force on the top plate while slowing the shearing of the well-confined disks and keeping the right boundary at a contactconfined force of 0.2 *** particle rearrangements were found to correspond to bulk force drops and were observed in a localized zone with a length of approximately 5 particle *** results help reveal the structure and mechanics of granular materials,and further investigations are ongoing.

关键词： granular matter force chain stick and slip

Visualization of force networks in 2D dense granular materials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2010年第1期4卷 109-115页

作者： Jianguo LIU Qicheng SUN Feng JIN State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China

Dense granular matter is a conglomeration of discrete solid and closely packed *** subjected to external loadings,the stress is largely transmitted by heavily stressed chains of particles forming a sparse network of larger contact *** understand the structure and evolution of force chains,a photoelastic technique was improved for determining stresses and strains in the assemblies of photoelastic granular disks in this paper.A two-dimensional vertical slab was *** contains 7200 polydispersed photoelastic disks and is subjected to a localized probe penetrating at the top of the slab to mimic the cone penetration *** interparticle contact force distribution was found a peak around the mean value,a roughly exponential tail for greater force and a dip toward zero for smaller *** force chain network around the probe tip was depicted,and the contact angle distribution of particles in force chains was found to be well aligned in the directions of major principal stress.

关键词： granular matter force chain multiscale modeling