硬质岩石卸荷破坏特性试验研究

 对硬质灰岩进行加轴压、卸围压试验，研究卸荷应力路径对其力学性质的影响，结合试验数据分析5种强度准则描述岩石卸荷破坏的适用性。Mohr-Coulomb强度准则和Hoek-Brown强度准则回归效果较差，考虑中间主应力影响的Drucker-Prager强度准则和Mogi-Coulomb强度准则回归效果较好，并且Mogi-Coulomb强度准则回归效果优于Drucker-Prager强度准则，抛物线型强度准则对高围压下的试验结果回归较好。岩石卸荷破坏发生强烈的体积扩容，从描述体积应变变化的角度对岩石卸荷破坏本构模型进行修正，理论模型结果与试验结果吻合较好。

EXPERIMENTAL STUDY OF HARD ROCK FAILURE CHARACTERISTIC UNDER UNLOADING CONDITION

The triaxial unloading tests of hard limestone are carried out. The mechanical properties changing with unloading stress path are studied. Five strength criteria are studied based on experimental results. Mohr-Coulomb criterion and Hoek-Brown criterion don?t describe the strength property of rock unloading failure. Drucker-Prager criterion and Mogi-Coulomb criterion fit experimental results very well. Mogi-Coulomb criterion fits experimental results better than Drucker-Prager criterion by comparison. The parabolic criterion is the best choice if the failure confining pressure is high. A rock unloading failure constitutive model is modified for describing the characteristic of volumetric strain. The theoretical model agrees well with experimental results.