为研究不同玄武岩纤维(BF)掺量下风积沙混凝土(ASC)轴心受压力学性能,试验以0%纤维掺量的混凝土为基准组,设计不同纤维掺量(0.05%、0.10%、0.15%和0.20%)的风积沙混凝土(BF-ASC),分析BF体积分数对风积沙混凝土轴心抗压强度、峰值应力、...为研究不同玄武岩纤维(BF)掺量下风积沙混凝土(ASC)轴心受压力学性能,试验以0%纤维掺量的混凝土为基准组,设计不同纤维掺量(0.05%、0.10%、0.15%和0.20%)的风积沙混凝土(BF-ASC),分析BF体积分数对风积沙混凝土轴心抗压强度、峰值应力、峰值应变和弹性模量的影响.结果表明:混凝土峰值应力和弹性模量均随着纤维体积分数的增加呈现先增大后减小的趋势,当BF掺量为0.10%时,其峰值应力和弹性模量分别为基准组的115.6%和112%;峰值应变和韧性指数则随纤维体积分数增大而增大,掺量为0.20%时,其峰值应变较基准组增长34.92%,韧性指数增长7.2%;BF-ASC应力-应变全曲线变化同普通风积沙混凝土都经历了弹性、塑性和破坏3个阶段;依据Carreira and Chu模型及过镇海模型对BF-ASC本构关系进行分段描述,其上升段符合Carreira and Chu本构模型,下降段符合过镇海模型;对考虑BF掺量的BF-ASC单轴受压本构模型进行回归分析,相关系数均大于0.98,该本构模型与试验曲线吻合度较高.展开更多
In this paper, a micro-mechanical model is implemented in software for the prediction of local mechanical properties of discontinuous short fiber reinforced composites. The model, based on the Mori and Tanaka method, ...In this paper, a micro-mechanical model is implemented in software for the prediction of local mechanical properties of discontinuous short fiber reinforced composites. The model, based on the Mori and Tanaka method, shear-lag, computational model, Nielsen-Chen model and Miwa’s model is used to predict the elastic behaviour of basalt short fiber reinforced with Al alloy composites. The Al/basalt Metal Matrix Composites (MMCs) contain basalt short fiber from 2.5% to 10% in steps of 2.5 wt.% and are fabricated using squeeze infiltration technique. The effects of fiber length and orientation on elastic properties of Al/basalt MMCs are investigated. A comparison between the experimental data and the theoretical data based on physical models is made, and the significance of the findings is discussed. The results show that as short basalt fiber content was increased from 2.5% to 10% by wt.%, an improvement in Young’s modulus of 13.26% has been observed. Optical microscopy was used to examine the general microstructure and fiber distribution in the composite produced. Scanning Electron Microscopy (SEM) was performed on the fractured surface to understand the failure mechanisms.展开更多
Several Cretaceous Carlin-like or hydrothermal gold deposits along the Garze-Litang suture zone and Early Cretaceous hydrothermal copper mineralization along the southeastern margin of the Songpan-Garze fold belt were...Several Cretaceous Carlin-like or hydrothermal gold deposits along the Garze-Litang suture zone and Early Cretaceous hydrothermal copper mineralization along the southeastern margin of the Songpan-Garze fold belt were presumed to have a magmatic heat source. However, no actual coeval mag- matic events nearby were discovered. Here, we report zircon SIMS U-Pb age, whole-rock geochemical and Sr-Nd isotopic data of the Xiqiu basalts in the southern end of the Yidun terrane, eastern Tibetan Plateau. New zircon U-Pb ages yield weighted mean ^206pb/^238U age of 117.7±1.6 Ma. The basalts are classified as calc-alkaline to alkaline and have relatively high MgO （4.77 wt.%-10.84 wt.%） and Mg number values （Mg^#=（100×Mg/（Mg＋Fe^2＋））; 45.35-67.28） and positive εNd（t） （t=118 Ma） values （＋1.86 to ＋3.2）, suggesting a OIB-like mantle source that is consistent with the normalized patterns of trace elements and rare earth elements （REEs）. Geochemical data suggest that the primary basaltic magma was generated by low degree partial melting of a heterogeneous source of peridotite-dominated with a minor component of garnet- eclogite or pyroxenite and experienced olivine＋clinopyroxene dominated fractional crystallization. The primary melt compositions calculated from the high MgO samples, in turn, suggest that the Xiqiu basalts were generated at 1.6-2.9 GPa with abnormally hot mantle potential temperatures from 1 465 to 1 540℃. The melting temperatures are similar to the abnormally hot mantle underneath the Colorado Plateau and hotter than the mid-ocean range basalt （MORB） mantle and normal intra-continental mantle. Combined with previous studies, the Cretaceous Xiqiu basalts allow us to reconstruct a tectonic and geodynamic evolution- ary model responsible for the Late Jurassic to Late Cretaceous geological records （magmatism, ore deposits and enhanced exhumation） in the Yidun terrane and southern Songpan-Garze fold belt.展开更多
The work is a vivid description of the structural relationship between brittle deformation of the Precambrian basement in the southern continental part of the Cameroon Line and intrusive Paleozoic and Mesozoic basalt ...The work is a vivid description of the structural relationship between brittle deformation of the Precambrian basement in the southern continental part of the Cameroon Line and intrusive Paleozoic and Mesozoic basalt dykes swarms. A multidisciplinary approach that involves a combination of remote sensing techniques and field studies show that the major trend of brittle structures correspond to well-known regional structures: N70°E (Adamawa Shear Zone), N135°E (upper Benue trend) and N30°E (Cameroon Volcanic Line) corresponding to E-W and N-S directions respectively. Basalt dykes are associated to NE-SW, E-W and NW-SE oriented fractures. An integration of the available information on brittle structures and basalt dykes directions suggest an emplacement of the Mesozoic and Paleozoic basalt dykes structurally controlled by Precambrian structures that were originated through Riedel’s fracture kinematic model with dextral strike-slip Adamawa Shear Zone as the main shear zone during late stage of the Pan-African collision. Spatially, the restriction of the basalt dykes to the corridor of the Adamawa Shear Zone indicate that a rejuvenation of Precambrian faults may very well be the origin of the dykes with possibility that they may have been reworked several times during the Phanerozoic eon.展开更多
文摘为研究不同玄武岩纤维(BF)掺量下风积沙混凝土(ASC)轴心受压力学性能,试验以0%纤维掺量的混凝土为基准组,设计不同纤维掺量(0.05%、0.10%、0.15%和0.20%)的风积沙混凝土(BF-ASC),分析BF体积分数对风积沙混凝土轴心抗压强度、峰值应力、峰值应变和弹性模量的影响.结果表明:混凝土峰值应力和弹性模量均随着纤维体积分数的增加呈现先增大后减小的趋势,当BF掺量为0.10%时,其峰值应力和弹性模量分别为基准组的115.6%和112%;峰值应变和韧性指数则随纤维体积分数增大而增大,掺量为0.20%时,其峰值应变较基准组增长34.92%,韧性指数增长7.2%;BF-ASC应力-应变全曲线变化同普通风积沙混凝土都经历了弹性、塑性和破坏3个阶段;依据Carreira and Chu模型及过镇海模型对BF-ASC本构关系进行分段描述,其上升段符合Carreira and Chu本构模型,下降段符合过镇海模型;对考虑BF掺量的BF-ASC单轴受压本构模型进行回归分析,相关系数均大于0.98,该本构模型与试验曲线吻合度较高.
文摘In this paper, a micro-mechanical model is implemented in software for the prediction of local mechanical properties of discontinuous short fiber reinforced composites. The model, based on the Mori and Tanaka method, shear-lag, computational model, Nielsen-Chen model and Miwa’s model is used to predict the elastic behaviour of basalt short fiber reinforced with Al alloy composites. The Al/basalt Metal Matrix Composites (MMCs) contain basalt short fiber from 2.5% to 10% in steps of 2.5 wt.% and are fabricated using squeeze infiltration technique. The effects of fiber length and orientation on elastic properties of Al/basalt MMCs are investigated. A comparison between the experimental data and the theoretical data based on physical models is made, and the significance of the findings is discussed. The results show that as short basalt fiber content was increased from 2.5% to 10% by wt.%, an improvement in Young’s modulus of 13.26% has been observed. Optical microscopy was used to examine the general microstructure and fiber distribution in the composite produced. Scanning Electron Microscopy (SEM) was performed on the fractured surface to understand the failure mechanisms.
基金supported by the National Natural Science Foundation of China (Nos. 41372212, 41672216, and 41702207)
文摘Several Cretaceous Carlin-like or hydrothermal gold deposits along the Garze-Litang suture zone and Early Cretaceous hydrothermal copper mineralization along the southeastern margin of the Songpan-Garze fold belt were presumed to have a magmatic heat source. However, no actual coeval mag- matic events nearby were discovered. Here, we report zircon SIMS U-Pb age, whole-rock geochemical and Sr-Nd isotopic data of the Xiqiu basalts in the southern end of the Yidun terrane, eastern Tibetan Plateau. New zircon U-Pb ages yield weighted mean ^206pb/^238U age of 117.7±1.6 Ma. The basalts are classified as calc-alkaline to alkaline and have relatively high MgO （4.77 wt.%-10.84 wt.%） and Mg number values （Mg^#=（100×Mg/（Mg＋Fe^2＋））; 45.35-67.28） and positive εNd（t） （t=118 Ma） values （＋1.86 to ＋3.2）, suggesting a OIB-like mantle source that is consistent with the normalized patterns of trace elements and rare earth elements （REEs）. Geochemical data suggest that the primary basaltic magma was generated by low degree partial melting of a heterogeneous source of peridotite-dominated with a minor component of garnet- eclogite or pyroxenite and experienced olivine＋clinopyroxene dominated fractional crystallization. The primary melt compositions calculated from the high MgO samples, in turn, suggest that the Xiqiu basalts were generated at 1.6-2.9 GPa with abnormally hot mantle potential temperatures from 1 465 to 1 540℃. The melting temperatures are similar to the abnormally hot mantle underneath the Colorado Plateau and hotter than the mid-ocean range basalt （MORB） mantle and normal intra-continental mantle. Combined with previous studies, the Cretaceous Xiqiu basalts allow us to reconstruct a tectonic and geodynamic evolution- ary model responsible for the Late Jurassic to Late Cretaceous geological records （magmatism, ore deposits and enhanced exhumation） in the Yidun terrane and southern Songpan-Garze fold belt.
文摘The work is a vivid description of the structural relationship between brittle deformation of the Precambrian basement in the southern continental part of the Cameroon Line and intrusive Paleozoic and Mesozoic basalt dykes swarms. A multidisciplinary approach that involves a combination of remote sensing techniques and field studies show that the major trend of brittle structures correspond to well-known regional structures: N70°E (Adamawa Shear Zone), N135°E (upper Benue trend) and N30°E (Cameroon Volcanic Line) corresponding to E-W and N-S directions respectively. Basalt dykes are associated to NE-SW, E-W and NW-SE oriented fractures. An integration of the available information on brittle structures and basalt dykes directions suggest an emplacement of the Mesozoic and Paleozoic basalt dykes structurally controlled by Precambrian structures that were originated through Riedel’s fracture kinematic model with dextral strike-slip Adamawa Shear Zone as the main shear zone during late stage of the Pan-African collision. Spatially, the restriction of the basalt dykes to the corridor of the Adamawa Shear Zone indicate that a rejuvenation of Precambrian faults may very well be the origin of the dykes with possibility that they may have been reworked several times during the Phanerozoic eon.
