不同加载速率对含孔试样变形特性影响研究  

Experimental investigation of the effect of different loading rates on deformation characteristics of porous samples

作　　者：张天军 景晨[1,3] 王喜娜 郭海龙 张磊 潘红宇[1,3] ZHANG Tianjun;JING Chen;WANG Xina;GUO Hailong;ZHANG Lei;PAN Hongyu(College of Safety Science and Engineering,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China;College of Energy and Engineering,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China;Key Laboratory of Mine Mining and Disaster Prevention and Control,Ministry of Education,Xi'an,Shaanxi 710054,China)

机构地区：[1]西安科技大学安全科学与工程学院,陕西西安710054 [2]西安科技大学能源学院,陕西西安710054 [3]西部矿井开采及灾害防治教育部重点实验室,陕西西安710054

出　　处：《采矿与安全工程学报》2021年第4期847-856,共10页Journal of Mining & Safety Engineering

基　　金：国家自然科学基金面上项目(51774234,51874234,51737007)。

摘　　要：为研究瓦斯抽采钻孔的静态加载速率效应,以含预制贯穿孔试样为实验对象,开展不同加载速率的单轴压缩试验并采用数字图像技术分析了试样的力学特性和破坏演化规律。结果表明:加载速率的变化对含孔试样力学特性有较大影响:随加载速率增大,抗压强度、起裂应力水平和变形能密度均逐渐增加但增幅放缓,弹性模量呈现出先增大后减小的趋势。加载过程中拉伸裂纹尖端的几何形状不断改变,拉应力强度因子KΙ减小,拉伸裂纹经历"扩展-闭合-扩展",拉伸裂纹长度与加载速率呈现较强的指数函数关系,加载速率为0.5mm/min时,拉伸长度达到最大为43.16 mm。含孔试样的破坏模式单一,呈中心对称;加载速率较小时,远场裂纹起裂位置距边缘较近,宏观裂纹以剪切破坏为主;加载速率较大时,宏观裂纹以拉伸破坏占主导地位,远场裂纹起裂位置距边缘较远。研究结果为揭示瓦斯抽采钻孔失稳的力学响应规律并阐述其演化过程提供一定的理论指导。To investigate gas extraction from static loading rate effect,with porous samples as experimental object,the uniaxial compression test of different loading rates was carry out,and the mechanical properties and damage evolution law of samples were analyzed through digital image technology.The results have shown that:the loading rate has a great influence on mechanical properties of porous samples:with the increase of loading rate,the compressive strength,crack stress level and strain energy density are increasing but growth is slowing,elastic modulus present the tendency of first increasing and then decreasing.During the loading process,the geometric shape of the tip of the tensile crack changes constantly,the tensile stress intensity factor KΙdecreases,and the tensile crack goes through"extend-closed-expansion".The maximum length of the tensile crack presents a strong exponential function relationship with the loading rate,which is 0.5 mm/min,and the maximum tensile length reaches 43.16 mm.The failure mode of the sample containing holes is single and symmetrical in the center;when the loading rate is low,the far-field crack initiation location is close to the edge,and the macro crack is mainly shear failure;when the loading rate is high,the macro crack is dominated by tensile failure,and the far-field crack initiation is far from the edge.The results provide theoretical guidance for understanding the mechanics response law of gas extraction borehole instability and revealing its evolution process.

关 键 词：抽采钻孔 加载速率效应 破坏模式 裂纹扩展 数字图像技术 

分 类 号：TU45[建筑科学—岩土工程]