应变率效应对600 MPa级高强钢筋混凝土框架结构抗震性能影响研究          下载免费PDF全文

孙传智  李爱群  缪长青  乔燕  左工 《世界地震工程》2019,35(2):165-170

为了更真实地进行钢筋混凝土结构抗震性能评估，应该考虑材料的应变率效应影响。600 MPa级高强钢筋作为新一代建筑钢材，尚无考虑应变率效应影响的600 MPa级高强钢筋混凝土框架结构抗震性能研究。首先进行了不同应变率下600 MPa级高强钢筋拉伸力学性能试验，利用试验数据拟合得到600 MPa级高强钢筋在不同应变率下的强度提高系数表达式，并利用OpenSees软件进行了配置600 MPa级高强钢筋混凝土框架结构抗震性能模拟分析，研究了应变率效应对框架结构抗震性能的影响。研究结果表明:随着应变率的增大，钢筋的屈服强度和极限强度均得到提高，屈服强度最大提高11.5%，极限强度最大提高8.9%；随着所考虑的材料应变率增加，配置600 MPa级高强钢筋框架结构最大顶点位移总体上呈减小趋势，地震波强度越强，应变率效应影响越大，而层间位移角减小幅值相差不大。研究成果可作为600MPa级高强钢筋混凝土框架结构抗震评估的依据。  相似文献   

SH波水平入射穿越垂直断层隧道动力响应分析     

杜修力  苏驰翔  黄景琦  王媛  赵密  欧阳文龙 《震灾防御技术》2019,14(2):269-280

结合黏弹性人工边界的时域波动输入方法和显式有限元法，设计了含垂直断层三维场地的SH波输入方法。基于建立的输入方法，研究了垂直断层对隧道地震响应的影响，并通过自由场算例验证了该方法具有较好精度。数值模拟结果表明:对于断层迎波侧的隧道结构，断层会对其地震动响应产生显著的放大作用，对于断层逆波侧的隧道结构，断层会对其产生隔离地震动的作用；相对周围围岩，断层介质的剪切波速越小，其产生的放大效应和隔震效果也会越显著；断层宽度越小，其对隧道地震动响应的影响范围也就越小，但是断层宽度的变化对于断层两侧隧道的地震动响应的影响并不明显。  相似文献   

级配碎石填料大三轴试验及累积塑性应变预测模型     

杨志浩  岳祖润  冯怀平  叶朝良  马德良 《岩土力学》2020,41(9):2993-3002

级配碎石作为重载铁路基床表层的主要填料，其受列车荷载的影响最大。因此，研究级配碎石在循环荷载作用下的动力行为及累积塑性应变演化特征变得尤为重要。首先，通过制备不同细粒含量的级配碎石填料，开展一系列大型动三轴试验，探究细粒含量、围压及动应力幅值对循环荷载作用下试样累积塑性应变的耦合影响机制。其次，基于塑性安定理论，确定不同应力水平下试样的动力行为，得到考虑围压及细粒含量参数的塑性蠕变状态临界动应力计算模型。最后，结合试验数据，建立考虑应力水平及细粒含量参数的塑性蠕变动力行为累积塑性应变预测模型，并明确各参数的物理意义。其研究成果可为既有重载铁路路基健康状态评估及考虑强度、变形综合控制的路基结构设计提供参考。  相似文献   

环渤海区域及邻区现今地壳构造运动形变特征分析     

赵旭坤  张俊  雷前坤  范成成 《大地测量与地球动力学》2019,39(11):1101-1105

将环渤海区域划分为5个次级块体，利用整体旋转与线性应变模型分析2009~2014年中国大陆构造环境监测网络的GPS对地观测速度场数据，得到相对于欧亚板块0.5°×0.5°的水平运动速度场和应变场。分析形变速度场和应变场的空间变化发现，环渤海区域整体上呈现0.25×10^-9/a的NW-SE 111.3°的双向趋势性扩张运动，太行块体、山西块体分别呈NW-SE 116.3°、NW-SE 130°的微弱扩张运动，胶辽块体、冀鲁块体和阴山-燕山块体分别存在NW-SE 144.3°、NE-SW 39.5°和NW-SE 155.6°的微弱压缩运动，其中太行块体的扩张运动量级相对于其他次级块体较大。尽管环渤海区域内部各次级块体的形变在空间上存在以上差异，但整体上环渤海区域主压应变轴方向基本为NEE-SWW，主张应变轴方向为NNW-SSE，且主压应变轴走向为NE 47.70°～89.74°，与利用地球物理方法得到的主压应变轴优势方向大体一致，表明环渤海区域现今地壳运动相对稳定。  相似文献   

Experimental determination of REE partition coefficients between zircon,garnet and melt: a key to understanding high‐T crustal processes          下载免费PDF全文

R. J. M. Taylor  S. L. Harley  R. W. Hinton  S. Elphick  C. Clark  N. M. Kelly 《Journal of Metamorphic Geology》2015,33(3):231-248

The partitioning of rare earth elements (REE) between zircon, garnet and silicate melt was determined using synthetic compositions designed to represent partial melts formed in the lower crust during anatexis. The experiments, performed using internally heated gas pressure vessels at 7 kbar and 900–1000 °C, represent equilibrium partitioning of the middle to heavy REE between zircon and garnet during high‐grade metamorphism in the mid to lower crust. The D_REE (zircon/garnet) values show a clear partitioning signature close to unity from Gd to Lu. Because the light REE have low concentrations in both minerals, values are calculated from strain modelling of the middle to heavy REE experimental data; these results show that zircon is favoured over garnet by up to two orders of magnitude. The resulting general concave‐up shape to the partitioning pattern across the REE reflects the preferential incorporation of middle REE into garnet, with D_Gd (zircon/garnet) ranging from 0.7 to 1.1, D_Ho (zircon/garnet) from 0.4 to 0.7 and D_Lu (zircon/garnet) from 0.6 to 1.3. There is no significant temperature dependence in the zircon–garnet REE partitioning at 7 kbar and 900–1000 °C, suggesting that these values can be applied to the interpretation of zircon–garnet equilibrium and timing relationships in the ultrahigh‐T metamorphism of low‐Ca pelitic and aluminous granulites.  相似文献   

Modeling the 2D behavior of dry‐stone retaining walls by a fully discrete element method          下载免费PDF全文

James J. Oetomo  Eric Vincens  Fabian Dedecker  Jean‐Claude Morel 《国际地质力学数值与分析法杂志》2016,40(7):1099-1120

The dry‐stone retaining walls (DSRW) have been tipped as a promising solution for sustainable development. However, before recently, their behavior is relatively obscure. In this study, discrete element method (DEM) approach was applied to simulate the plane strain failure of these walls. A commercial DEM package (PFC2D™) was used throughout this study. The authors used a fully discrete approach; thus, both the wall and the backfill were modeled as discrete elements. The methodology for obtaining the micromechanical parameters was discussed in detail; this includes the three mechanical sub‐systems of DSRWs: wall, backfill and interface. The models were loaded progressively until failure, and then the results were compared with the full‐scale experimental results where the walls were loaded, respectively, with hydrostatic load and backfill. Despite its complexity and its intensive calculation time, DEM model can then be used to validate a more simplified approach. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

体应变地震波最大振幅与地震震级和震中距的统计关系探讨     

姜佳宁  吴利军 《中国地震研究》2017,31(1):107-115

Based on the body strain record of Tiantanghe station from 2008 to 2014,we make a statistical analysis of the relationship between the maximum amplitude of the body strain record and the surface-wave magnitude,epicenter distance of the earthquakes,which occurred in the Chinese mainland and its surrounding areas with MS≥6. 0 and the rest of the world with MS≥7. 0. According to statistical results,we propose a statistical formula between the surface-wave magnitude of earthquake and the maximum amplitude of the body strain record,the epicenter distance: M_S~*= 0. 37 ln A_max+ 0. 57 ln D + 0. 07. We can also derive a theoretical estimation formula for the maximum amplitude: A_max=e~(2. 7(M_S~*-0. 07))D~(-1. 54). This demonstrates that the maximum amplitude of the body strain record increases exponentially with the increase of the surface-wave magnitude, and decreases with the increase of the epicenter distance,and shows a negative correlation with their product. We further discuss the necessity of adding instruments with high frequency sampling to earthquake monitoring, and dicuss the prospects for precise earthquake prediction in future.  相似文献   

The strain‐dependent spatial evolution of garnet in a high‐P ductile shear zone from the Western Gneiss Region (Norway): a synchrotron X‐ray microtomography study          下载免费PDF全文

A. Macente  F. Fusseis  L. Menegon  X. Xiao  T. John 《Journal of Metamorphic Geology》2017,35(5):565-583

Reaction and deformation microfabrics provide key information to understand the thermodynamic and kinetic controls of tectono‐metamorphic processes, however, they are usually analysed in two dimensions, omitting important information regarding the third spatial dimension. We applied synchrotron‐based X‐ray microtomography to document the evolution of a pristine olivine gabbro into a deformed omphacite–garnet eclogite in four dimensions, where the 4^th dimension is represented by the degree of strain. In the investigated samples, which cover a strain gradient into a shear zone from the Western Gneiss Region (Norway), we focused on the spatial transformation of garnet coronas into elongated garnet clusters with increasing strain. The microtomographic data allowed quantification of garnet volume, shape and spatial arrangement evolution with increasing strain. The microtomographic observations were combined with light microscope and backscatter electron images as well as electron microprobe (EMPA) and electron backscatter diffraction (EBSD) analysis to correlate mineral composition and orientation data with the X‐ray absorption signal of the same mineral grains. With increasing deformation, the garnet volume almost triples. In the low‐strain domain, garnet grains form a well interconnected large garnet aggregate that develops throughout the entire sample. We also observed that garnet coronas in the gabbros never completely encapsulate olivine grains. In the most highly deformed eclogites, the oblate shapes of garnet clusters reflect a deformational origin of the microfabrics. We interpret the aligned garnet aggregates to direct synkinematic fluid flow, and consequently influence the transport of dissolved chemical components. EBSD analyses reveal that garnet shows a near‐random crystal preferred orientation that testifies no evidence for crystal plasticity. There is, however evidence for minor fracturing, neo‐nucleation and overgrowth. Microprobe chemical analysis revealed that garnet compositions progressively equilibrate to eclogite facies, becoming more almandine‐rich. We interpret these observations as pointing to a mechanical disintegration of the garnet coronas during strain localization, and their rearrangement into individual garnet clusters through a combination of garnet coalescence and overgrowth while the rock was deforming.  相似文献   

易县地震台四分量钻孔应变观测震前异常特征     

赵慧琴  王艳  张肖  马栋 《地震地磁观测与研究》2017,38(4):132-136

通过对河北易县地震台钻孔应变资料进行处理,发现在2014年9月6日涿鹿4.3级和2015年9月14日昌黎4.2级地震前,该台四分量钻孔应变观测到显著前兆异常变化,与2012年5月28日唐山4.8级地震前出现的异常相似度较高,异常形态均表现为"来快去慢",均在极值附近维持数日后,逐渐恢复原值过程中发生地震。  相似文献   

巴颜喀拉块体东缘形变及九寨沟地震孕震环境数值分析   总被引：6，自引：3，他引：3       下载免费PDF全文

庞亚瑾  程惠红  张怀  石耀霖 《地球物理学报》2017,60(10):4046-4055

2017年8月8日四川发生九寨沟M7.0地震,是继2008年汶川M8.0地震后发生在巴颜喀拉块体东部的又一强震.现今GPS速度观测数据显示,2008年汶川地震前后的1999-2007年和2011-2016年两个时间段内巴颜喀拉块体东部地表速度场存在明显的差异.本文以实际GPS速度观测资料为约束,构建三维有限元地球动力学模型,分别计算分析了两个时段内震源区及周边现今地壳形变、弹性应变能和应力积累特征,进一步探讨汶川地震的发生对九寨沟地区变形及应力的影响.数值模拟结果显示,汶川地震之后(2011-2016年)巴颜喀拉块体东部的地壳形变、弹性应变能积累及应力积累速率均明显大于震前,增加量值达1.5-3倍;九寨沟地震发震断裂上库仑应力增长率在1999-2007年约为0.7 kPa·a~(-1),2011-2016年间增至1.2 kPa·a~(-1).上述结果表明,现今巴颜喀拉块体东部地壳应力积累过程有利于左旋走滑型九寨沟地震的发生,汶川地震的发生调整了区域应力状态,加速了九寨沟地震的孕育过程.  相似文献