Experimental study on dynamic mechanical characteristics and failure features of surrounding rock in layered composite rock mass tunnels

作者：Yang Wang, Chuanxin Rong, Hao Shi, Yanzhe Li, Runze Zhang · 发表于：Results in Engineering · 年份：2025 · DOI：10.1016/j.rineng.2025.107013 · 被引用次数：5 · 研究领域：Rock Mechanics and Modeling、Geomechanics and Mining Engineering、Grouting, Rheology, and Soil Mechanics

To study the dynamic mechanical behavior and failure characteristics of layered composite rock masses under complex geological conditions, specimens of circular and straight-wall semi-circular arch tunnels with varying soft and hard rock thickness ratios were prepared using rock-like materials. Vertical tunnel impact tests were conducted employing a high-speed camera, a separated Hopkinson compression rod (SHPB) test system, and a digital image correlation (DIC) system. Dynamic stress-strain curves, fracture morphology, specimen fragment fractal dimension, energy dissipation, crack evolution, and failure modes were then analyzed. The results indicate that the influence of tunnel geometry on the dynamic mechanical properties of layered composite rock masses should not be underestimated. The wave attenuation amplitude of the straight-wall semi-circular arch tunnel specimens exceeds that of the circular tunnel specimens, with its peak strength and peak strain being relatively lower. Additionally, the ratio of soft to hard rock layers significantly affects fracture morphology. As the proportion of soft rock increases, the degree of fracture in the composite specimens under impact load increases substantially. Furthermore, the relationship between energy proportions and the soft rock ratio was analyzed, with an exploration of the failure characteristics of the surrounding rock in the composite formation. The differences in crack germination types for tunnel specimens containing ci...