基于二维数字图像相关技术的块系花岗岩超低摩擦效应实验研究

基于国内外超低摩擦效应的实验研究现状,设计了块系花岗岩超低摩擦效应模拟实验。制作了中心含圆柱形洞室的花岗岩立方体模型试样,运用自主研发的实验设备研究了在静荷载的基础之上施加动态荷载后块系花岗岩的变化特征。实验过程中采用二维数字图像相关测试方法(2D-DIC),获得了试件表面的全场位移信息,依据位移信息求出块体加速度值,利用牛顿第二定律对试件受力分析,求得了块系岩体摩擦力随时间的变化曲线。结果表明:2D-DIC测试技术能够准确的测得石块的位移变化,依据位移变化可以证实伴随着水平向扰动荷载作用,洞口上方岩块左右两侧节理间隙逐步增大,岩块间的摩擦力降低,且摩擦力的变化周期与扰动荷载的周期相同;利用2D-DIC测试技术是有效的,从实验的角度验证了超低摩擦效应的存在。

Experimental study on ultra low friction effect of granite block based on two dimensional digital image correlation technique

Based on the experimental research of ultra low friction effect at home and abroad,the experiment of ultra low friction effect on block rock mass was designed.In this paper,granite block was cut into cube specimens with a cylinder hole in its center.The variation characteristics of the granite block under the dynamic loading combined with the static loading were studied by using the self developed experimental equipment.The two dimensional digital image correlation test method (2D DIC) was used to measure the full field displacement information of specimen surface,and the acceleration value was obtained based on the displacement information.The curve of friction versus time for block rock mass was obtained based on the Newton’s second law.The main findings show that the 2D DIC test technology can accurately measure the displacement change of the block rock mass.Based on the displacement,the gaps at two sides of the rock above the hole were gradually increased and the friction was reduced with the effect of horizontal disturbance load.The change of the friction and the disturbance load cycle has the same cycle.It effectively verifies the existence of ultra low friction phenomenon by using the 2D DIC technique.