圆形洞室模型在双轴加载下的力学特征分析

为探究圆形洞室围岩在不同围压下加载过程中的力学特征变化,对制作的含圆形洞室的类岩石材料进行双轴加压试验,运用数字图像技术记录全场应变演化过程,并根据室内试验建立颗粒流模型,探究了围压对洞室围岩的抗压强度以及裂纹的发育的影响。结果表明：尺寸效应对模型的力学特征影响较大,圆形洞室模型峰值抗压强度随着洞室尺寸的增加而减小；当围压增大时,压剪作用增强,洞室模型的破坏模式由以张拉应变为主向拉剪复合破坏为主转变；圆形洞室应变集中区域会随着围压的增大由洞口上下侧向两帮转移；当围压逐渐增大,张拉作用被抑制,洞口两侧破坏程度逐渐增加,收缩变形程度逐渐增大；最后通过数值模拟验证了圆形洞室围岩在不同围压下加载过程中的力学变化特征。

Mechanical characteristics analysis of circular cavity model under biaxial loading

In order to explore the change of mechanical characteristics of surrounding rock of circular cavern under different confining pressures, biaxial compression tests were carried out on the rock-like materials containing circular caverns. The digital image technology was used to record the whole field strain evolution process, and the particle flow model was established according to the test to explore the influence of confining pressure on the compressive strength of surrounding rock of cavern and the development of cracks. The results showed : The size effect has a great influence on the mechanical characteristics of the model, and the peak compressive strength of the circular cavity model decreases with the increase of the cavity size. When the confining pressure increases, the compressive shear effect increases, and the failure mode of the cavern model changes from tensile strain to tensile shear composite failure. With the increase of confining pressure, the strain concentration area of circular cavity transfers from the upper and lower sides of the hole. When the confining pressure increases gradually, the tension is inhibited, the damage on both sides of the hole increases gradually, and the shrinkage deformation increases gradually. Finally, the mechanical variation characteristics of surrounding rock of circular cavern under different confining pressures are verified by numerical simulation.