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现有的锚板极限承载力研究大多是采用线性或非线性Mohr-Coulomb破坏准则在砂质地基中进行的,然而Mohr-Coulomb破坏准则并不适合分析岩质地基中的抗拔结构。采用Hoek-Brown破坏准则构建了一个曲线型的破坏机制,根据极限分析上限定理求出了条形锚板抗拔力的表达式。通过变分计算,得到了极限状态下条形锚板的抗拔力和岩体破裂面的上限解。为了证明所采用方法的有效性,当材料参数B=1时,采用与Mohr-Coulomb破坏准则等效的土体参数,计算了曲线型破坏机制下条形锚板的极限抗拔力,并与已有计算结果进行了比较。结果表明,采用曲线型破坏机制得到的锚板极限抗拔力与直线型多块体破坏机制的结果基本一致,证明了所采用的曲线形破坏机制是正确的。参数研究表明:在其他参数不变的情况下,锚板极限抗拔力和破坏面都随岩体参数B的增大而减小。
Most of the existing research on ultimate bearing capacity of anchor plate is carried out in sandy soil based on linear or non-linear Mohr-Coulomb failure criterion. However, Mohr-Coulomb failure criterion is not suitable for analysis of anti-pull structure in rock mass. A Hoek-Brown failure criterion is used to construct a curve-type failure mechanism. According to the upper bound theorem of limit analysis, the expression of the pullout resistance of strip anchor plates is obtained. Through the variational calculation, the ultimate pullout force of the strip anchor and the upper limit solution of the rock mass rupture surface are obtained. In order to prove the effectiveness of the proposed method, when the material parameter B = 1, the equivalent soil resistance parameters of Mohr-Coulomb failure criterion are used to calculate the ultimate pullout strength of strip anchor under curve failure mechanism. The calculation results have been compared. The results show that the ultimate pullout strength of anchor plate obtained by the curved failure mechanism is basically the same as that of the linear multi-block failure mechanism, which proves the correctness of the curved failure mechanism. Parametric studies show that the ultimate tensile strength and failure surface of anchor plates decrease with the increase of rock mass parameter B under the condition of other parameters.