不同围压下茅口灰岩渐进性破坏的试验研究
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摘要
利用MTS815电液伺服控制刚性试验机进行不同围压下茅口灰岩三轴压缩试验,通过计算绘得相应裂隙体积应变图,分析得出裂纹起始应力、裂纹破坏应力。结果表明:随着围压的增大,应力门槛值均呈非线性增长态势,当围压超过17 MPa时,裂纹起始应力、裂纹破坏应力分别增加48.5%和20.1%,茅口灰岩延性开始增强;裂纹破坏应力为峰值强度的64%~75%,三轴压缩下茅口灰岩裂隙不稳定发展阶段较长;环向应变值随围压增大而增大,当轴力超过裂纹破坏应力进入裂隙不稳定发展阶段,环向应变增大2.7~3.2倍,用环向-轴向应力应变曲线图能较好的反映岩石应力门槛值。
Under different confining pressure,triaxial compressive strength of Maokou limestone is tested by MTS 815 test system. By calculating data,the fracture strain figure is painted and crack initiation stress and crack failure stress are obtained,it shows that: with the increase of confining pressure,three stress thresholds increase,the period of unstable crack growth is longer than uniaxial compressive strength,crack propagation is limited under confining pressure. Under the same confining pressure,circ strain is larger than axial strain,circ strain grows quickly when axial force over crack initiation stress,a sharp increase in circ strain when axial force over crack failure stress,the circ- axial stress strain curve can reflect three stress thresholds.
Under different confining pressure,triaxial compressive strength of Maokou limestone is tested by MTS 815 test system. By calculating data,the fracture strain figure is painted and crack initiation stress and crack failure stress are obtained,it shows that: with the increase of confining pressure,three stress thresholds increase,the period of unstable crack growth is longer than uniaxial compressive strength,crack propagation is limited under confining pressure. Under the same confining pressure,circ strain is larger than axial strain,circ strain grows quickly when axial force over crack initiation stress,a sharp increase in circ strain when axial force over crack failure stress,the circ- axial stress strain curve can reflect three stress thresholds.
引文
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[2]周建超,贾纯驰,吕建国.含预制裂纹的脆性岩石单轴压缩下渐进性破坏过程的试验研究[J].探矿工程,2012,39(9):66-70.
[3]周辉,孟凡震,卢景景,等.硬岩裂纹起裂强度和损伤强度取值方法探讨[J].岩土力学,2014,35(4):913-925.
[4]张晓平,王思敬,韩庚友,等.岩石单轴压缩条件下裂纹扩展试验研究—以片状岩石为例[J].岩石力学与工程学报,2011(9):1772-1781.
[5]田勇,俞然刚.不同围压下灰岩三轴压缩过程能量分析[J].岩土力学,2014,35(1):118-129.
[6]李英杰,张顶立,宋义敏,等.软弱破碎深埋隧道围岩渐进性破坏试验研究[J].岩石力学与工程学报,2012,31(6):1138-1147.
[7]梁昌玉,李晓,王声星,等.岩石单轴压缩应力-应变特征的率相关性及能量机制试验研究[J].岩石力学与工程学报,2012,31(9):1830-1838.
[8]王洪亮,范鹏贤,王明洋,等.应变率对红砂岩渐进破坏过程和特征应力的影响[J].岩土力学,2011,32(5):1340-1346.
[9]徐洪宇,赖远明,喻文兵,等.人造多晶冰三轴压缩强度特性试验研究[J].冰川冻土,2011,33(5):1120-1126.