仿真介质扩孔锚承载性状模型试验研究

Study on Bearing Behaviors of Under-reamed Anchor by Model Test in Simulating Media

通过混凝土、水泥砂浆以及不同侧限条件密砂仿真岩土材料介质室内模型试验,模拟分析不同类型岩土实体内不同尺寸扩大头锚杆的抗拔性能,探讨了扩大头锚杆的承载机理与破坏模式,研究结果表明岩土体强度与约束条件对扩孔锚极限抗拔力与承载性状影响显著,扩孔锚扩大头直径合理取值范围为1.5≤D/d≤3.0,扩大头长度对扩孔锚承载力的影响可以忽略不计,其设计参数只要满足扩大头抵抗剪切破坏的能力要求即可。同时基于研究成果提出了对扩孔锚设计与施工有实际参考价值的相关建议。

Model tests have been carried out for simulating soil-rock material from concrete, cement mortar and the medium density sand in different unconfined conditions. Then, the uplifting properties have been researched for the under-reamed anchor with different sizes of expanded heads in different types of rock and soil, the bearing mechanism and failure modes for the under-reamed anchor have been investigated as well. The study results show that the rock-soil strength and unconfined conditions have important influence on the bearing properties and limited anti-pull force of the under-reamed anchor. The rational size of the expanded head about the under-reamed anchor is 1.5≤D/d≤3.0, the influence of expanded head＇ s length on the bearing capacity of the under-reamed anchor can be ignored, and the length of expanded head is only necessary to satisfy the capability to resist shear strength. Based on the resuits, some recommendations with practical reference values have been proposed for the design of and construction with the under-reamed anchor.