不同温度下大理岩静动力学特性研究

Study on the static and dynamic characteristics of marble at different temperatures

高温下岩石的力学参数是地下工程设计、施工以及支护的重要依据,因此研究高温下岩石力学特性具有重要的实际意义。在云南省卡房地区现场取得大理岩样本,在6种温度(25、100、200、400、600、800℃)下进行力学试验,共制作72个试样,在单轴压缩冲击试验系统上对高温作用后的大理岩试样分别进行静、动载试验,结果表明:静载作用时,大理岩试样在不同温度下的应力-应变曲线可分为压密、弹性、塑性变形和破坏4个阶段,峰值应力从79.70 MPa降至33.27 MPa,降幅为58.3%;动载作用时,峰值应力从224.00 MPa降至43.11 MPa,降幅达80.8%;大理岩试样在静、动载作用下,峰值应变均随温度的升高而增大,动载时的峰值应变普遍大于静载作用时的;静载作用时的峰值应变增长率要略大于动载作用时的;弹性模量均随温度的升高而降低;静载作用下,弹性模量与温度的线性关系明显;动载作用下,弹性模量的数据较分散,在400℃之后,弹性模量急剧减小,弹性模量随应变率的增大有增大的趋势;在同一温度下,加载速率越大,弹性模量越大。

The mechanical parameters of rock at high temperature is an important basis for the engineering design,construction and support of underground works,so it has a practical significance to study the mechanical properties of rock at high temperature.Marble samples were taken at Kafang mining site in Yunnan Province and prepared for 72 testing samples.The dynamic tests were carried out at different temperatures:25℃,100℃,200℃,400℃,600℃and 800℃respectively.Both the static and dynamic loading tests on marble samples at high temperatures were undertaken based on the uniaxial compression impact testing system.From the testing results we can see that with the performance of static loading there were four stages:compaction,elastic deformation,plastic deformation and failure presented on the stress-strain curve where the peak stress decreased from 79.70 MPa to 33.27 MPa accordingly by 58.3%.While dynamic loading was being performed the peak stress decreased from 224.00 MPa to 43.11 MPa by 80.8%.During either static or dynamic loading,the peak strain of marble increases with the rise of temperature and that under dynamic load is generally greater than that under static load.Under the action of static load,the rate of increase of peak strain is slightly higher than that under dynamic load.The modulus of elasticity decreases with the rise of temperature.With the static loading,the linear relationship between the elastic modulus and temperature is remarkable.With the dynamic loading,the points of scattered elastic modulus data exhibits on or around the curve,which drops sharply behind the point at 400℃,the modulus of elasticity tends to go up with the increase of strain rate.Under a given temperature,the higher the loading rate is,the larger the modulus of elasticity is.