石英砂岩双轴压缩条件下的微观组构演化规律研究
投稿时间:2019-08-13  修订日期:2020-09-01  点此下载全文
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作者单位E-mail
肖尊群 武汉工程大学兴发矿业学院 547309418@qq.com 
王鑫 武汉工程大学兴发矿业学院 1024028184@qq.com 
姜亦男 武汉工程大学兴发矿业学院  
董琼英 武汉工程大学兴发矿业学院  
杨凯 武汉工程大学土木与建筑工程学院  
曹童童 武汉工程大学兴发矿业学院  
邓震 中国石油管道防腐工程有限公司  
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)顺层坡含碎石滑带土变形及渗流特性研究(51804222)
中文摘要:以石英砂岩室内双轴试验为基础,建立PFC2D颗粒流数值模型,颗粒间选用平行粘结接触,根据实验所得弹性模量、泊松比、峰值应力对天然、饱和状态下石英砂岩试样进行不同围压下的细观参数标定,最终得到与室内试验基本吻合的应力-应变曲线。分析加载过程中接触力、配位数、孔隙度等细观参数的演化规律,以此来探究石英砂岩的破坏机理。结果表明:双轴压缩试验的细观参数标定可不考虑抗剪强度指标c、φ值的影响。破坏前、后,试样各方向统计范围内颗粒间都存在法向接触力和切向接触力。围压的存在影响试样的起始配位数、孔隙度,对配位数和孔隙度的改变速率影响很小。试样空间孔隙度的演化在一定程度上反映了试样破坏时内部结构的变迁,能更加直观的反映试样的破坏模式。研究结果说明:这种数值方法在探寻岩石试样的微观组构演化特征方面是可行的。
中文关键词:双轴压缩试验  微观组构  切向接触力  法向接触力  配位数  细观参数  演化
 
Study on the microfabric evolution of quartz sandstone under biaxial compression
Abstract:Based on the indoor biaxial test of quartz sandstone, the numerical model of PFC2D particle flow was established. Parallel bond contact was selected between the particles. According to the experimental results, the elastic modulus, Poisson"s ratio and peak stress were different for quartz sandstone samples under natural and saturated conditions. The meso-parametric calibration under confining pressure finally yields a stress-strain curve that is basically consistent with the laboratory test. The evolution law of mesoscopic parameters such as contact force, coordination number and porosity during loading was analyzed to explore the failure mechanism of quartz sandstone. The results show that the meso-parameter calibration of the biaxial compression test can ignore the influence of the shear strength indicators c and φ. Before and after the failure, the normal contact force and the tangential contact force existed between the particles in the statistical range of the sample in all directions. The presence of confining pressure affects the initial coordination number and porosity of the sample, and has little effect on the rate of change of coordination number and porosity. The evolution of the spatial porosity of the sample reflects the change of the internal structure when the sample is destroyed to a certain extent, which can reflect the failure mode of the sample more intuitively. The results show that this numerical method is feasible in exploring the microstructural evolution characteristics of rock samples.
keywords:biaxial compression test  microstructure  tangential contact force  normal contact force  coordination number  mesoscopic parameters  evolution
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