自然与饱水状态下岩溶灰岩力学性质及能量机制试验研究

 为研究饱水对岩溶灰岩力学性质和能量机制的影响，利用RMT–150B岩石力学试验系统分别对自然和饱水状态试样进行单轴压缩和常规三轴压缩试验。试验结果表明：饱水对岩溶灰岩的强度和变形特征影响显著，2种状态下试样峰值强度与围压的回归关系可用以主应力表达的Coulomb强度准则表征；岩溶灰岩试样的似软化系数及其降低速率均随围压增加而减小。从能量角度对2种状态试样损伤破坏过程中的能量特征进行试验研究，结果表明：饱水状态试样吸收的总应变能U，峰前储存的可释放应变能 及二者随轴向应变的增加速率均小于自然状态的对应值；随含水量增加 逐渐下降，峰后 释放率随围压增加而逐步下降，整体上饱水试样的 释放率较大；峰值应力处试样各应变能随围压线性递增，2种状态下耗散能差值随围压的变化是试样破坏形式差异的内在原因；岩溶灰岩试样全过程能量实时演化过程具有阶段性，2种状态下压密和弹性变形阶段耗散能差别细微，但进入屈服阶段后，饱水状态试样耗散能增加更快。

EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES AND ENERGY MECHANISM OF KARST LIMESTONE UNDER NATURAL AND SATURATED STATES

In order to study the influence of water saturation on mechanical properties and energy mechanism of karst limestone，uniaxial and pseudo-triaxial compression tests are carried out under natural and saturated states by rock mechanics test equipment RMT–150B. The testing results of mechanical properties indicate that saturation has a significant effect on the strength and deformation characteristics of karst limestone；and the regression relationship between peak strength and confining pressure can be expressed by Coulomb strength criterion in principal stress. Similar softening coefficient and their reduction rate decrease with the increased confining pressure. From the perspective of energy，the energy features and energy mechanism in the process of rock failure are studied by tests；and then some conclusions are drawn as fellows：the total absorbed energy U，releasable strain energy before peak stress and their increasing rates with axial strain under saturated condition are less than corresponding values of natural specimen. The release rate of after peak stress declines under two states with confining pressure，especially the release rate of for saturated specimen is larger in general. Each strain energy at peak stress increases linearly with the confining pressure；and the intrinsic reason for destroyed style difference is that the difference of dissipated energy under two states varies with confining pressure. Real-time evolution process of karst limestone specimen can be divided into different stages. As for dissipated energy，it differs slightly in compression and elastic deformation stage under two states；but in yield phase，dissipated energy of saturated rock increases faster.