强风化凝灰岩地质条件下岩石锚杆基础试验研究

针对玉环变—乐清变500 kV双回输电线路工程大跨越塔建设面临的强风化凝灰岩地质条件,进行了9组单锚基础和6组群锚基础的竖向上拔静载荷试验,研究岩石锚杆基础的破坏模式和承载特性,为设计提供参考依据。在试验加载过程中进行了锚筋的应变测试,分析锚筋的内力变化规律,得到岩石锚杆基础的破坏模式和承载特性。试验结果表明：单锚锚筋内力随荷载的增大而增大,随埋深的增加而减小,超过一定埋深范围后逐渐消减至接近0;群锚基础的极限抗拔承载力并非单锚基础极限抗拔承载力的简单叠加,而是存在＂群锚效应＂问题。该研究为岩石锚杆基础在输电线路工程中的实际应用提供了一定的参考和依据。

Experimental Study on Rock Anchor Foundations under Strongly Weathered Tuff Geological Condition

Strongly weathered tuff geological condition was encountered under the construction of large crossing towers in the Yuhuan Substation – Yueqing Substation 500 kV double-circuit power transmission line project. Static pullout tests were conducted for nine single anchor foundations and six group anchors foundations. The variation of internal force and strain of anchors were tested and analyzed. Meanwhile,the failure modes and bearing characteristics of the rock anchor foundations were obtained. The experimental results show that the internal force of single anchor increases with the increase of load. The internal force decreases with the increase of buried depth,and reduces to zero beyond certain berried depth. The ultimate pullout capacity of group anchor foundation is not the simple sum of that of single anchor foundation,in which the group anchor effect exists. This study also provides a reference and basis for practical engineering application.