侧向变形控制下的灰岩破坏规律及其峰后本构关系

根据不同含水状态（干燥和泡水饱和）和不同围压条件下的灰岩岩样的三轴压缩全程试验和峰后加卸载循环试验，分析干燥和饱水状态灰岩的变形破坏规律、围压对灰岩峰值强度和残余强度及破裂面角度的影响，研究灰岩峰前、峰后强度与变形之间的关系。结果表明：灰岩的破坏方式不仅和围压水平有关，而且和岩石的含水状态相关；灰岩的残余强度与峰值强度相比很小，且随峰后加卸载循环次数的增加继续衰减；该类灰岩在低围压下产生拉剪组合破坏，导致其破裂角度较Coulomb 准则预测值偏大，在高围压下发生完全剪切破坏，破裂角度与Coulomb 准则计算结果吻合；岩石轴向应力在峰值前是由其轴向应变决定的，峰后则由侧向变形控制，随侧向变形的增加逐渐衰减至残余强度。在此基础上建立了灰岩峰后本构模型，给出了分段的岩石应力-应变关系函数。利用该模型对岩石应力-应变全过程进行计算，计算结果与试验结果吻合较好。

Limestone failure law and post-failure constitutive relation in the control of lateral deformation

Based on the mechanical tests of limestone which were conducted under different moisture conditions(fully saturated and dry) and different confining pressures，and the cyclic loading tests of broken limestone，analyzed the law of deformation and failure，the effect to peak and residual strength and angle of rupture brought by confining pressure，and researched the law between strength and deformation of whole process.The study results show that:different confining pressure leads different form of failure，and pore water will strengthen the brittleness of limestone.The residual strength is much smaller than the peak strength，and decreases as the cyclic loading.The form of failure about this classification of limestone is tension shearing under low confining pressure which leads a higher angle of rupture，and fully shearing under high confining pressure which leads a angle as Coulomb criterion.The axial stress is caused by axial strain before failure，but controlled by lateral strain after failure and decreases to the residual strength as the lateral strain increasing.Based on that，limestone constitutive model and stress strain function were founded，which accord with the test results.