基于裂缝效应的锚固体单轴抗压强度试验研究

The mechanical properties of jointed rock mass are the basic basis and research hotspot for the stability control of anchored surrounding rock. Based on the orthogonal experimental design and using the vertical anchoring form, three crack characteristics, namely the number of cracks, the intermittency degree of cracks and the dip angle of cracks, are selected as experimental factors, and the influence of various crack factors on the uniaxial compressive strength of the anchored body is studied through range analysis and variance analysis. The results show that when the angle between the crack plane and the force direction of the anchored body is less than 90°, the anchored body is more prone to sudden failure after reaching the peak strength; at the same time, compared with the intact anchored body, the main controlling crack factors of the compressive strength of the anchored body under different crack states are different. Under the factor increment environment in this paper, the influence degree on the compressive strength from large to small is in turn the dip angle of cracks, the number of cracks and the intermittency degree of cracks. In addition, a linear relationship formula between the compressive strength of the anchored body with cracks and that without cracks is established based on the above laws, and the data prove that this theoretical formula can better predict the compressive strength of the anchored body with cracks. The research results can provide guidance for predicting the generation and development of key parts of soft rock roadways.

节理岩体力学特性是锚固围岩稳定性控制的基本依据和研究热点。基于正交试验设计,采用垂直布锚形式,选取裂缝数量、裂缝断续程度和裂缝倾角3种裂缝特性作为试验因素,并通过极差分析和方差分析研究裂缝各因素对锚固体单轴抗压强度的影响。结果表明:裂缝平面与锚固体受力方向交角小于90°时,锚固体达到峰值强度后更易发生突发性破坏;同时,相较于完整锚固体而言,不同裂缝状态下锚固体抗压强度的主控裂缝因素不同,在本文的因素增量环境下,对抗压强度影响程度由大到小依次为裂缝倾角、裂缝数量和裂缝断续程度。此外,基于上述规律建立有缝锚固体和无缝锚固体抗压强度线性关系式,数据证明该理论公式可以较好地预测含裂缝锚固体的抗压强度。研究成果可为预测软岩巷道关键部位的产生与发展提供指导。