岩锚基础破坏形态与承载力计算的探究

Research into the Failure Modality and the Pulling Force Resistance of the Rock Anchorage

岩石锚杆基础作为输电线路中塔基的一种特殊形式,可以充分发挥原状岩体的力学性能,提供良好的抗拔性能,逐渐被推广应用于架空输电线路的塔基之中。借助有限元法(FEA)模拟软件MSC.Marc,分别在Ⅳ类差岩体、Ⅲ类一般岩体和Ⅱ类好岩体中模拟了单锚式和直锚式岩锚基础上拔荷载作用下的破坏形态。结果表明:岩体强度直接影响岩锚基础的破坏形态,与真型试验结果基本相符;现行设计规范中的破坏模式与实际不符,由于所考虑的提供岩体的抗拔力过大,依其设计计算的结果可能导致不安全,有待进一步的完善和修订,以及可应用直锚基础的地质条件要求过于苛刻;也证明了有限元Marc软件能直观有效的辅助计算分析岩土工程实际问题。同时,笔者根据真型试验与数值模拟结果总结了岩锚基础的5种破坏形态,建立了新的破坏模型,进行了其抗拔承载力计算的探究,得到了该最大值Fmax和最小值Fm in的计算公式。

The rock anchorage, as special form of tower foundation in transmission line, can fully utilize the mechanical capability of the original rock, and it can supply good pulling resistance capacity. So such anchorage is popularized gradually in the tower foundation engineering for the overhead transmission line. In this paper, the different type of rock anchorage including the single - anchorage and direct - anchorage is simulated, by means of the software of MSC. Mare, as simulation software based on the principle of finite element analysis （ FEA）. In this paper the rock anchorage failure modality is simulated and analyzed in three different state of rock intensity including poor （ IV class）, common （III class） and good （II class）. The results indicate that the rock intensity is a main factor to the failure modality, which is consistent to the real tests. The current failure modality in criterion was not actual in practice, and the geological condition for the foundation was restricted too rigorously, for the anchorageuse. The availability of Mare was substantiated too for resolving the geotechnical engineering practical problem. At the same time, the authors summarized 5 kinds of the failure modality, and studied the force of pulling resistance by the result of the real tests and FEA. Finally, the Fmax and Fmin computing formula were obtained.