摘要
利用MTS815 Flex Test GT电液伺服岩石力学试验系统对完整灰岩及断续(裂隙、断裂)灰岩进行三轴压缩试验,研究不同围压下完整灰岩及断续灰岩的强度及变形特征。基于试验结果建立断裂灰岩圣维南体力学模型模拟岩石破裂形成断续结构后失稳摩擦滑动,在此基础之上,采用单结构面理论研究限定其发展的条件。试验结果表明:完整灰岩及断续灰岩试样峰前弹性模量随围压的增大并没有产生明显的变化,且裂隙灰岩峰前弹性模量与完整灰岩基本一致;完整灰岩表现为低围压下的脆性向高围压下的塑性破坏转化的变形特征,而裂隙灰岩在不同围压条件下均表现为塑性破坏,断裂灰岩则表现为理想弹塑性变形;完整灰岩及断续灰岩峰值强度都随着围压的增大而增大,相同围压下裂隙灰岩强度低于完整灰岩强度,但相差不大,循环加载对断裂灰岩强度影响较小;灰岩破坏形成断裂结构后,破裂面间的摩擦决定断裂灰岩承载能力,当破裂面剪应力超过摩擦力时,将发生塑性滑移,通过增大围压可以增强破裂面间摩擦进而提高断裂灰岩承载能力,抑制塑性滑移。
The conventional triaxial compression tests were carried out to investigate the deformation and strength properties of the complete limestone and the intermittent （ ie cracked or fractured） limestone under different confining pressures by means of the MTSS15 Flex Test GT rock mechanics servo-controlled test system. Based on the test results,the Saint-Venant body was constructed to simulate the unstable friction sliding of intermittent limestone formed from rock failure. And then the single structure surface theory was adopted to research the limited condition for its development. The results show that there is no obvious change in the peak elastic modulus of the complete limestone and the intermittent limestone specimens along with the increase of confining pressure, and the peak elastic modulus of the cracked limestone is essentially the same as that of the complete limestone. The deformation feature of the complete limestone specimens changes from brittle failure under low confining pressure into plastic failure under high confining pressure.But the cracked limestone specimens always present plastic deformation under different confining pressure conditions and the fractured limestone specimens present ideal elastic-plastic deformation. Both the peak strength of the complete limestone and the intermittent limestone grow with the increase of the confining pressure, and the peak strength of the intermittent limestone is lower than that of the complete limestone under the same confining pressure even though the difference is small, moreover the cyclic loading has little influence on the strength of the fractured limestone. The bear- ing capacity of the fractured limestone depends on the friction between rupture surface after the complete limestone failed into fault structure. The plastic slip would occur when the shear stress exceeded the friction force. It can enhance the friction and thereby improve the bearing capacity of the fractured limestone by increasing the confining pressure so as to inhibit plastic slip.
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2014年第2期301-306,共6页
Journal of China Coal Society
基金
国家重点基础研究发展计划(973)资助项目(2010CB226802)
国家自然科学基金煤炭联合基金重点资助项目(51134018)
关键词
断续灰岩
力学特性
摩擦
三轴压缩
塑性滑移
intermittent limestone
mechanical behavior
friction
triaxial compression
plastic-slip
