锚杆长期拉拔荷载下岩体内部应变时空演化特征

锚固岩体的长期强度是围岩稳定性控制的基本依据和研究热点。以岩锚复合结构为研究对象,运用预埋应变技术,通过全长时效方程黏结锚杆在长期荷载下的拉拔蠕变试验,研究了锚固体内部应变的时空演化规律。通过对比提出多项式作为拉拔蠕变时效方程的理论依据。研究结果表明:岩锚复合体的内部蠕变曲线不是单调递增,而是存在多个峰值;随着时间延伸,荷载对锚固段不同部位应变发展趋势的影响也不同,具体表现为加载初期锚固前端应变响应积极,随着时间推移,锚固末端应变与前端趋于一致;锚固段的同一部位轴向应变一般大于横向应变;相比伯格斯模型,多项式时效方程能更好地描述岩锚复合体锚固段的蠕变过程。研究结果可以为锚固工程稳定性控制提供理论依据。

Temporal and Spatial Evolution Characteristics of Internal Strain of Rock Mass under Long-term Pull-out Load of Anchor

The long-term strength of anchored rock mass is the basis and hot research of surrounding rock stability control. Taking the rock-anchor composite structure as the research object， the time-space evolution law of strain in the anchor was studied through the pull-out creep test of the full long-term aging equation bonded anchor under long-term load by using the embedded strain technology. Then， the polynomial was proposed as the theoretical basis of the pull-out creep aging equation. The results showed that the internal creep curve of rock-anchor composite is not monotonically increasing， but has multiple peaks； As time goes on， the influence of load on the strain development trend of different parts of the anchorage section is also different， which shows that the front strain at the initial stage of loading has a positive response， and the strain at the end of anchorage tends to be consistent with that at the front as time goes by； The axial strain at the same part of the anchorage section is generally greater than the transverse strain； Compared with the Burgers model， the polynomial aging equation can better describe the creep process of the anchorage section of rock-anchor composite. The research results can provide theoretical basis for stability control of anchorage engineering.