岩石三轴流变扰动效应损伤演化特征试验研究  

Experimental study on damage evolution characteristics of rock under triaxial rheological disturbance

作　　者：王波[1] 陆长亮 黄子康 胡仕宇 WANG Bo;LU Changliang;HUANG Zikang;HU Shiyu(School of Safety Engineering,North China University of Science and Technology,Sanhe 101601,China)

机构地区：[1]华北科技学院安全工程学院,河北三河101601

出　　处：《采矿与岩层控制工程学报》2021年第4期1-10,共10页Journal of Mining and Strata Control Engineering

基　　金：河北省自然科学基金资助项目(E2019508088);中央高校基本科研业务费资助项目(3142020062)。

摘　　要：为了从微观损伤角度建立不同围压下岩石是否进入“强度极限邻域”的判别标准,对红砂岩进行常规三轴流变扰动逐级加载试验,通过核磁共振手段对流变扰动前后岩石进行分析对比,得到不同围压下T_(2)谱曲线、孔隙率、孔径分布。试验结果表明:①不同围压下的岩石存在一个流变应力阈值,当岩石应力状态小于该阈值时,施加扰动载荷T_(2)谱曲线第1,2谱峰高度均无明显的变化;当岩石应力状态大于该阈值时,T_(2)谱曲线第1,2谱峰出现突增现象,且产生新的谱峰曲线,同时T_(2)谱曲线发生向右偏移现象,说明该应力阈值是判别岩石是否进入“强度极限邻域”内、外的界限;②不同围压下岩石存在一个“强度极限邻域”界限范围,当纵向应力小于该应力时,T_(2)谱曲线谱峰总面积在扰动前后变化不明显,当纵向应力大于该应力时,T_(2)谱曲线谱峰总面积明显增大,且出现第3个T_(2)谱曲线谱峰面积,说明处于“强度极限邻域”外的岩石损伤较小,不易产生流变扰动破坏,反之会加大岩石内部损伤,最终致使岩石发生扰动失稳破坏;③岩石在围压0.5 MPa时比围压1.5,3.0 MPa下先进入“强度极限邻域”范围,围压的存在提高了岩石长期强度,随着围压的增大损伤逐渐减小;④核磁共振成像图谱清楚地反映出“强度极限邻域”内、外岩石孔隙结构变化特征。In order to establish the criterion of whether the rock enters the"strength limit neighborhood"under different confining pressures from the micro-damage point of view,the red sandstone was tested by conventional triaxial rheological disturbance step-by-step loading,and the rocks before and after the rheological disturbance were analyzed and compared using NMR,the T_(2) spectrum curve,porosity and pore size distribution under different confining pressures are obtained,and the micro criterion of"strength limit neighborhood"of rock is established.①There is a threshold value of flow stress in rocks under different confining pressures.When the stress state of rocks is less than the threshold value,the height of the first and second peaks of T_(2) spectrum curve under disturbance load has no obvious change;When the stress state of rock is larger than the threshold value,the first and second peaks of T_(2) spectrum curve not only appear sudden increase,but also appear new peak curve,and T_(2) spectrum curve appears right shift phenomenon.It shows that the stress threshold is the limit to judge whether the rock enters into the"strength limit neighborhood";②There is a limit range of"strength limit neighborhood"for red sandstone under different confining pressures.When the stress state of rock is greater than the threshold value;the first and second peaks of T_(2) spectrum curve suddenly increase and new peak curve is generated,it shows that the damage of rock outside the"strength limit neighborhood"is small and it is not easy to produce rheological disturbance,on the other hand,it will increase the internal damage of rock,and finally lead to rock instability;③When the confining pressure is 0.5 MPa,the rock enters the range of"strength limit neighborhood"first,and the existence of confining pressure increases the long-term strength of rock,and the damage decreases with the increase of confining pressure;④The NMR images clearly reflect the pore structure change characteristics of rocks in and out of"strength limit n

关 键 词：三轴流变 强度极限邻域 微观损伤 核磁共振 T_(2)谱曲线 

分 类 号：TD325[矿业工程—矿井建设]