摘要
断裂岩石在长期地质力学作用下发生蠕变,并伴有声发射,此声发射规律可为岩石稳定性监测和预警提供有益借鉴。为了研究断裂岩石蠕剪过程的声发射特征,在法向力恒定的条件下,对巴西拉破坏和压剪破坏2种不同形式的断裂砂岩进行蠕变分级剪切试验,并运用全信息声发射信号分析仪进行实时监测,得到2种不同破坏形式的断裂岩石在不同蠕剪阶段声发射能量和蠕变剪切位移关系。同时,利用声发射定位系统对蠕剪过程中断裂岩石的双翼啮合和磨损进行定位,结合断裂面等高线图,预测断裂岩石在长期蠕剪中的破坏位置和破坏形式。试验结果表明:断裂岩石蠕剪失稳前声发射信号缺失;巴西拉破坏岩样蠕剪中后期声发射能量出现波峰,每段剪切位移加载前期能量达到局部最大值,之后呈现下降趋势;压剪破坏岩样蠕剪中期声发射能量出现低谷,每段剪切位移加载中期声发射能量出现局部波峰。同时,由声发射定位可知,2类断裂岩石啮合面中心部位都最先发生破坏,断裂面蠕变剪切的初期破坏具有方向性,破坏初期沿断裂面呈现带状分布并与剪切方向垂直。
Under a long-term geomechanical loading,creep deformation would occur in fractured rocks,accompanying with acoustic emission(AE). The laws of AE are meaningful to monitor and warning of the rock in stability. In order to look into the AE features of fractured rocks during creep shear,the direct creep shear experiment of fractured rocks induced by compressive shear and Brazilian tension was carried out under constant normal force. AE technology was used to detect the acoustic events during the creep shear. The relationship between AE energy and creep shear displacement at different loading stages is revealed. Meanwhile,the locations of the interlocks and the micro-contact fractures are also identified the laser scanned contour maps of the fractured rock surfaces by the AE events. The experiment shows that there is a signal blank phenomenon of AE events before the instability occurs. Regarding to the fractured rocks induced by Brazilian tension,the peak of AE energy mainly appears at the middle and late stages of the creep shear process,and AE energy reaches local maximum at the early stage of each loading followed with its downward trend;for the fractured rocks induced by compressive shear,AE energy valley appears at the middle stage of the creep shear process,and at each shear loading a small peak of AE energy appears at the middle stage. In addition,AE position detection shows that the micro-contact fractures mainly occur first at the central part of the interlocked surfaces. The initial micro-contact fractures present a directional character that a zonal distribution develops perpendicular to the shear direction at early loading stages.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2015年第S1期2948-2958,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(41172264)
国家自然科学基金重点支撑项目(u1361208)
关键词
岩石力学
断裂岩石
蠕变剪切
声发射
巴西破坏
压剪破坏
rock mechanics
fractured rock
creep shear
acoustic emission
Brazilian tension failure
compressive shear failure
