节理形态及吻合度对应力波传播影响试验

Effects of joint roughness and joint matching degree coefficient on stress wave propagation

摘要:

为探讨节理形态及其吻合程度对应力波传播的影响,分析不同节理吻合系数JMC及其几何分布对节理的动态力学特性和应力波衰减规律的影响,试验采用水泥砂浆材料制备圆柱体试样模拟岩石试样,通过将圆柱体一端面分割为不同数量的扇形凹面来量化描述节理分布形态,同时对两个节理分布形态相同的试样旋转不同角度获得不同节理接触面积的组合试样.分离式霍普金森压杆（SHPB）冲击试验结果表明:当组合试样的节理分布形态相同时,试样应力-应变曲线在加载段的非线性随节理接触面积减小逐渐增大,这反映了节理接触面积越小节理对试样加载初期的力学响应越明显；同样在组合试样的节理分布形态相同时,应力波透射系数和节理等效刚度均随节理接触面积增大呈线性增大；当组合试样的节理接触面积相同时,节理接触面几何分布越分散（扇形凹面数量越多）应力波透射系数和等效刚度越大,而且接触面积越大几何分布形态作用影响愈明显.

Abstract:

To explore the influence of joint morphology and its degree of anastomosis on the propagation of stress waves, effects of joint matching coefficient (JMC) and its geometric distribution on the dynamic mechanical properties of joints and the propagation of stress waves were analyzed. Cement mortar samples were adopted to prepare cylindrical specimens for simulating rock samples. The distribution pattern of joints was quantified by dividing the end surface of a cylinder into different numbers of fan-shaped concave surfaces. Meanwhile, two specimens with same joint morphology and distribution were obtained at different angles. The split Hopkinson pressure bar (SHPB) was employed for impact test and the results showed that when the joint morphology of the specimens were the same, the nonlinearity of the stress-strain curves in the loading section increased with the increase of the joint contact area. It revealed that the smaller the contact area was, the more obvious the mechanical response of the joint to the initial stage of loading was. Similarly, under the condition of same joint morphology of the composite specimens, the stress wave transmission coefficient and the joint equivalent stiffness increased linearly with the increase of the joint contact area. When the contact area of the joint specimens was the same, the more dispersed the geometric distribution of the joint surface (the more the number of the fan-shaped concave) was, the greater the transmission coefficient and the equivalent stiffness of the stress wave became. The larger the contact area of the joint was, the more obvious the joint geometry distribution effect was.