加卸荷条件下大理岩变形特征及能量演化

为揭示深埋大理岩在不同应力路径下的变形特征和能量演化特征,基于大理岩的常规三轴试验和卸荷三轴试验,分析了大理岩变形破坏过程中变形和能量演化的围压效应和应力路径影响。结果表明:大理岩在加卸荷条件下均表现出显著的围压效应;卸荷条件下大理岩的损伤扩容应力阈值和峰值强度较加载条件下的低;加载应力路径下能量耗散阶段占比更大,卸荷应力路径下能量聚集阶段占比更大;加卸荷条件下损伤扩容点对应的总能量和弹性应变能与围压具有良好的线性关系;针对峰值应力对应的总能量、弹性应变能及耗散能,加载应力路径下其均与围压具有正线性关系,而卸荷应力路径下均与围压成指数关系。基于以上结论,提出了确定大理岩破坏点的定量方法,结合应力-应变关系曲线,有效地解决了高围压作用下大理岩破坏点难以确定的问题,为深埋洞室围岩的稳定性分析提供依据。

Deformation Characteristics and Energy Evolution of Marble under Loading and Unloading Conditions

To reveal the deformation characteristics and energy evolution characteristics of deep buried marble under high stress conditions and different stress paths, we examined the confining pressure effect and stress path influence of deformation and energy evolution during the deformation and failure of marble via conventional triaxial test and unloading triaxial test. Results reveal significant confining pressure effects under both loading and unloading stress paths. The damage expansion stress threshold and peak strength of marble under unloading conditions are lower than those under loading conditions. In terms of energy evolution, the proportion of energy dissipation stage in the process of deformation and failure under loading stress path accounts for a larger proportion than that under unloading stress path, while energy accumulation stage is greater in unloading stress path. The total energy and elastic strain energy corresponding to the damage expansion point under both stress paths are in good linear relations with confining pressure. At peak stress, the total energy, elastic strain energy and dissipation energy are linear functions of the confining pressure under loading stress path, and exponential functions under unloading stress path. Based on the above conclusions, a quantitative method to determine the failure point of marble is proposed. In association with the stress-strain relationship curve, the method effectively addresses the difficulty in determining the failure point of marble under high confining pressure. The research findings offer basis for the stability analysis of the surrounding rock of deep-buried chamber.