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
Discontinuities have significant role on the behavior of rock masses with respect to several types of instabilities. Excavability, deformability, bearing capacity and slope stability of the rock masses should be inves...Discontinuities have significant role on the behavior of rock masses with respect to several types of instabilities. Excavability, deformability, bearing capacity and slope stability of the rock masses should be investigated considering the discontinuity characteristics with particular emphasis on the geomechanical properties. Kinematic analyses mostly provide an insight to the instabilities, however the dimensions of the blocks bounded by discontinuities, their geomechanical properties and the geometry of the slope should also to be taken into account. The study area is in the abandoned stone quarry in Bayrakl? district of ?zmir residential area. Due to the excavations and discontinuity orientations, instabilities have occured. Miocene aged andesites and altered agglomerates of Yamanlar Volcanics form the bimrock mass. The study area is located within a sheared zone, bounded by strike slip fault zone. Intact andesite blocks were encountered in altered agglomerate matrix, forming a volcanic bimrock. Wedge and planar sliding and block toppling were observed within the area. Detailed discontinuity surveying was conducted, combined with core drillings. Several typical locations were detected where prismatic blocks of andesites are bound to experience block toppling. Such locations are nearby the top of the steep slopes. Agglomerates are subjected to mainly sliding and the blocks have been formed not by gravity but by peculiarities of thevolcanic sedimentation and, probably by subsequent tectonics. In order to determine the mechanism of the sliding and toppling in more details, the relation of the blocks and the slope geometry were investigated. Bimrock type volcanic rock masses sometimes do not tend to accommodate the general rules of toppling and sliding due to their anisotropic settings.展开更多
Bimrocks are characterized by their geotechnically significant blocky structure,presenting complex shear behavior.This study investigates the shear behavior and dilatancy of bimrocks featuring a rock-like matrix,such ...Bimrocks are characterized by their geotechnically significant blocky structure,presenting complex shear behavior.This study investigates the shear behavior and dilatancy of bimrocks featuring a rock-like matrix,such as conglomerates.The study addresses a gap in current research,which has predominantly examined the shear behavior of soil-matrix bimrocks(bimsoils).Laboratory direct shear tests were performed on idealized models with varying volumetric block proportions(VBPs).The results highlight that blocks exert both positive and negative effects on shear strength,dilation,and block breakage factor(BF),depending on VBP.Results indicate 40%and 60%as critical VBPs,revealing distinct shear strength trends within this range,contrary to the dominant downward trend.Blocks positively impact dilation and BF between 20%and 50%VBP,while negatively affecting them beyond this range.Blocky skeleton inherently promotes stable dilatancy under normal stress increments and intensifies stress dependency of shear strength.Variations in dilation angle concerning normal stress and VBP suggest the potential for characterizing this factor using equivalent strength and roughness,akin to rockfill materials.Indirect assessments of equivalent strength revealed positive effects of blocks when VBP was between 30%and 70%.Lastly,the findings indicate that blocks notably impact pre-and post-peak behaviors by reducing shear stiffness and inducing local hardening phases.This study also discusses the similarities and distinctions in the function of blocks within soil-like and rock-like matrices.It offers new insights into the exact role of blocks in bimrock shear behavior beyond the traditional interpretation through the variation of friction and cohesion.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.
文摘Discontinuities have significant role on the behavior of rock masses with respect to several types of instabilities. Excavability, deformability, bearing capacity and slope stability of the rock masses should be investigated considering the discontinuity characteristics with particular emphasis on the geomechanical properties. Kinematic analyses mostly provide an insight to the instabilities, however the dimensions of the blocks bounded by discontinuities, their geomechanical properties and the geometry of the slope should also to be taken into account. The study area is in the abandoned stone quarry in Bayrakl? district of ?zmir residential area. Due to the excavations and discontinuity orientations, instabilities have occured. Miocene aged andesites and altered agglomerates of Yamanlar Volcanics form the bimrock mass. The study area is located within a sheared zone, bounded by strike slip fault zone. Intact andesite blocks were encountered in altered agglomerate matrix, forming a volcanic bimrock. Wedge and planar sliding and block toppling were observed within the area. Detailed discontinuity surveying was conducted, combined with core drillings. Several typical locations were detected where prismatic blocks of andesites are bound to experience block toppling. Such locations are nearby the top of the steep slopes. Agglomerates are subjected to mainly sliding and the blocks have been formed not by gravity but by peculiarities of thevolcanic sedimentation and, probably by subsequent tectonics. In order to determine the mechanism of the sliding and toppling in more details, the relation of the blocks and the slope geometry were investigated. Bimrock type volcanic rock masses sometimes do not tend to accommodate the general rules of toppling and sliding due to their anisotropic settings.
文摘Bimrocks are characterized by their geotechnically significant blocky structure,presenting complex shear behavior.This study investigates the shear behavior and dilatancy of bimrocks featuring a rock-like matrix,such as conglomerates.The study addresses a gap in current research,which has predominantly examined the shear behavior of soil-matrix bimrocks(bimsoils).Laboratory direct shear tests were performed on idealized models with varying volumetric block proportions(VBPs).The results highlight that blocks exert both positive and negative effects on shear strength,dilation,and block breakage factor(BF),depending on VBP.Results indicate 40%and 60%as critical VBPs,revealing distinct shear strength trends within this range,contrary to the dominant downward trend.Blocks positively impact dilation and BF between 20%and 50%VBP,while negatively affecting them beyond this range.Blocky skeleton inherently promotes stable dilatancy under normal stress increments and intensifies stress dependency of shear strength.Variations in dilation angle concerning normal stress and VBP suggest the potential for characterizing this factor using equivalent strength and roughness,akin to rockfill materials.Indirect assessments of equivalent strength revealed positive effects of blocks when VBP was between 30%and 70%.Lastly,the findings indicate that blocks notably impact pre-and post-peak behaviors by reducing shear stiffness and inducing local hardening phases.This study also discusses the similarities and distinctions in the function of blocks within soil-like and rock-like matrices.It offers new insights into the exact role of blocks in bimrock shear behavior beyond the traditional interpretation through the variation of friction and cohesion.
