Design and construction of engineering structures in geomaterials with block-in-matrix texture(referred as bimrock) such as conglomerates,breccias and agglomerates are challenging tasks for engineers.When dealing with...Design and construction of engineering structures in geomaterials with block-in-matrix texture(referred as bimrock) such as conglomerates,breccias and agglomerates are challenging tasks for engineers.When dealing with these materials in important structures such as open pits with high walls and pillars of deep underground mines,understanding the complete stress-strain behavior,including post-peak region,is a formidable yet crucial engineering practice.To study the post-peak behavior of bimrocks,artificial specimens were fabricated with a mixture of rock blocks and a cementing agent.All the experiments were conducted under uniaxial compression using a servo-control testing machine.The results show that the specimens with the highest block proportion(around 90% by mass) showed a small decrease in stress with strain increment in the post-peak region.The specimens with lower block proportions were characterized by an approximately steep fall in stress and following to residual stress.Based on the study,it is inferred that all the artificial specimens undergo post-failure deformation and the type of post behavior depends on rock block proportions.展开更多
A micromechanical model of double-walled carbon nanotube (DWCNT) pullout from a composite matrix is presented with the interfacial residual stress and van der Waals (vdW) forces taken into consideration.The interfacia...A micromechanical model of double-walled carbon nanotube (DWCNT) pullout from a composite matrix is presented with the interfacial residual stress and van der Waals (vdW) forces taken into consideration.The interfacial residual stress induced by thermal expansion coefficient (TEC) mismatch is introduced via thermo-elastic constitutive relations.The influence of vdW interactions between two layers of DWCNT on the interfacial stress distributions of DWCNT and matrix is analyzed.The analytical expressions of interfacial shear stress and the axial stresses of DWCNT and matrix are derived,respectively.Furthermore,the influences of temperature change,interfacial friction coefficient,DWCNT aspect ratio,DWCNT volume fraction and the relative modulus between DWCNT and matrix are illustrated and discussed.展开更多
文摘Design and construction of engineering structures in geomaterials with block-in-matrix texture(referred as bimrock) such as conglomerates,breccias and agglomerates are challenging tasks for engineers.When dealing with these materials in important structures such as open pits with high walls and pillars of deep underground mines,understanding the complete stress-strain behavior,including post-peak region,is a formidable yet crucial engineering practice.To study the post-peak behavior of bimrocks,artificial specimens were fabricated with a mixture of rock blocks and a cementing agent.All the experiments were conducted under uniaxial compression using a servo-control testing machine.The results show that the specimens with the highest block proportion(around 90% by mass) showed a small decrease in stress with strain increment in the post-peak region.The specimens with lower block proportions were characterized by an approximately steep fall in stress and following to residual stress.Based on the study,it is inferred that all the artificial specimens undergo post-failure deformation and the type of post behavior depends on rock block proportions.
基金supported by the National Natural Science Foundation of China (Grant no. 10802057 and 51075298)the Key Program of National Natural Science Foundation of China (Grant no. 10732080)the National Basic Research Program of China (973 Program,Grant no.2012CB937500)
文摘A micromechanical model of double-walled carbon nanotube (DWCNT) pullout from a composite matrix is presented with the interfacial residual stress and van der Waals (vdW) forces taken into consideration.The interfacial residual stress induced by thermal expansion coefficient (TEC) mismatch is introduced via thermo-elastic constitutive relations.The influence of vdW interactions between two layers of DWCNT on the interfacial stress distributions of DWCNT and matrix is analyzed.The analytical expressions of interfacial shear stress and the axial stresses of DWCNT and matrix are derived,respectively.Furthermore,the influences of temperature change,interfacial friction coefficient,DWCNT aspect ratio,DWCNT volume fraction and the relative modulus between DWCNT and matrix are illustrated and discussed.
