岩石锚杆基础抗拔承载力计算方法探究

Researches on pull-out capacity calculating method of rock bolt foundation

岩石锚杆基础作为架空输电线路塔基中的一种特殊基础型式,可以充分发挥原状岩体的力学性能,具有良好的抗拔性能。根据目前岩石锚杆基础原型试验的结果,《架空送电线路基础设计技术规定》中所推荐的单锚基础抗拔承载力计算模型中,理想45°破坏模式与实际不符,按其设计计算值偏差较大,可能导致设计成果不安全。为此,依据极限平衡原理基于围岩强度建立了较为合理的抗拔承载力计算模型,力学推导得出了相关公式,并进行了简化。通过推导公式计算值与实测值、设计值对比验证可知,抗拔承载力极限值位于Fmin～Fmax区间内,与推荐公式F推的计算值一致性较好,能满足工程应用精度,具有可行性。

As a special type of the tower-foundation in overhead transmission lines,the rock bolt foundation can give full play to the mechanical properties of rock masses in original state and provide a good pull-out performance.The results of the current prototype test of rock bolt foundation show that in the calculating model of the single anchor foundation’s pull-out capacity which is recommended in The technical requirements in overhead transmission lines foundation design,the hypothetical model of the ideal 45° does not match the actual damage.The calculation based on it makes larger deviations and the results may lead to unsafe design.To this end,based on the limit equilibrium principle and rock intensity,a more reasonable pull-out capacity calculating model,is established,and the relevant formula by mechanical derivation is obtained and simplified.Through the comparison and verification among the calculated values based on derived formula,actual values and designed values,the pull-out capacity is located in Fm in ? Fmaxrange limits and in good consistency with the calculated values of recommended formula F推.The results are feasible and able to meet the precision of engineering applications better.