循环荷载下断续裂隙岩体的变形特性

断续裂隙岩体在地震、波浪冲击、动力机器运转等动力循环荷载作用下的疲劳特性是岩石力学的一个基础课题。采用预制断续裂隙类砂岩模型试样单轴动循环加载试验,借助测试到的荷载–位移曲线从不可逆变形与总变形随循环次数的演化规律入手探讨了含2、3条裂隙试样循环荷载下的疲劳变形规律,并对影响裂隙试样疲劳变形的加载频率、循环荷载水平及裂隙空间位置等因素进行了讨论分析。研究发现:断续裂隙岩体的疲劳变形演化规律与完整岩石、完全离散的节理化岩体一致,均可划分为3个阶段:初始变形阶段、等速变形阶段与加速变形阶段;其疲劳破坏时的变形量与周期荷载的上限荷载在静态荷载–位移曲线峰值后区对应的变形量相当;同时,断续裂隙岩体疲劳变形除受加载频率及荷载水平的影响之外,还受到裂隙空间位置的明显影响。

Deformation properties of rock mass with intermittent cracks under cyclic loading

The fatigue properties of the rock mass with intermittent cracks under blasting and earthquake are the most basic problems in rock mechanics.The force-displacement curves were tested under uni-axial cyclic loading in the experiment and the specimens were made of sandstone-like modeling materials containing two or three pre-existing cracks with different geometry distributions.In virtue of the analysis of irreversible deformation and total deformation with cyclic number,the fatigue deformation properties of the cracked specimens were discussed.Then,some influential factors,such as loading frequency,load level and geometrical position of cracks on fatigue properties of the cracked samples were analyzed and discussed.It was indicated that the development of fatigue deformation of samples with intermittent cracks could be divided the into three stages: the initial deformation stage,the constant deformation rate stage and the accelerative deformation stage which were same as the intact rock and block-jointed rock;the fatigue deformation limit corresponding to the maximum cyclic load was equal to that of post-peak locus of static complete force-displacement curve;and the fatigue deformation was controlled not only by the loading frequency and the load level,but also by the geometrical position of intermittent cracks.