【作者】 梁卫国； 徐素国； 莫江； 吴迪； 张传达；

【Author】 LIANG Weiguo,XU Suguo,MO Jiang,WU Di,ZHANG Chuanda(Mining Technology Institute,Taiyuan University of Technology,Shanxi,Taiyuan 030024,Shanxi China)

【机构】 太原理工大学采矿工艺研究所；

【摘要】 加载应变率(时间相关性)是影响岩石应力应变曲线形状的一个重要环境因素,应变率效应是脆性岩石强度与变形特性的一个典型特征。对于韧性软岩,其强度与变形特性同样具有强烈的时间相关性,流变即为一例。本文以层状盐岩体矿床中的NaCL岩盐与无水芒硝盐岩为研究对象,在实验室内进行了10-5—10-3/s范围内的单轴压缩强度与变形特性的应变率效应研究。研究发现:NaCL岩盐与无水芒硝盐岩的单轴抗压强度基本不随加载应变速率的变化而变化,但弹性模量随应变速率的增高而增大;同一应变速率条件下,无水芒硝盐岩强度略高于NaCL岩盐;两类盐岩的泊松比均随加载应变速率的增大而减小;随加载应变速率的增大,试件在应力达到峰值时的应变减小,其变形模量与加载应变速率呈对数关系;试件破裂方式不随加载应变速率而变,NaCL岩盐试件破裂为柱状劈裂或楔型剪切,而无水芒硝盐岩则表现为单斜剪切。对扩容应力与极限强度之比统计结果表明,盐岩扩容应力与极限强度之比(平均值)介于87.3%～91.0%之间,表明盐岩在扩容之前均具有很强的弹粘性变形能力,扩容一旦开始,试件即很快达到其极限强度。更多还原

【Abstract】 strain rate(time dependence)is one of the important environmental factors affecting stress-strain curve of rock,strain rate effect on strength and deformation is evident for brittle rock.For ductile and soft rock,the time dependence of mechanical and deformation properties is much heavier,rheology is a perfect illustration.In this paper,halite and thenardite,which are the main constitutes in bedded salt rock deposits,were chosen as the experimental samples.The uniaxial compression behavior of the samples were recorded and analyzed with loading strain rate increase from 10-5/s to 10-4/s,and ultimately to 10-3/s.It was found that the ultimate strength of the two lithologies hardly change with loading strain rate,however the elastic modulus increased with it.The uniaxial compressive strength of thenardite is larger than that of halite when loaded with the same strain rate.Opposite to the trend of the elastic modulus,the poisson`s ratio of the two lithologies decreased with strain rate for the halite and thenardite specimens.Similarly,the strain of the tested specimens at the point of ultimate strength decreased with loading strain rate.Finally,a logarithmic relationship between deformation modulus and loading strain rate was established with the test results in the paper.During the experiments,it was found that all the halite specimens were broken in the type of brittle tensile fracture around the specimen column face,while single shear failure along an inclined plane in the specimens was the character of thenardite break.The damage types of the halite and thenardite hardly changed with loading strain rate.Ratio of stress at the point of the volume increase to the ultimate compressive strength of the tested specimens was also calculated and analyzed in the paper,and an average value of 87.3%～ 91.0% of the ratio was recorded,which is obviously larger than that of general rocks.The large ratio value demonstrated that salt rock possesses large elastic to viscous deformation capacity before the volume increase during compression,and the ultimate strength will soon be arrived as long as the volume increase started in the specimen body.更多还原