加固岩体的预应力锚索拉力松弛分析模型

Analysis Model for Relaxation Effect of Pulling Force of Prestressed Anchor Cables Used in Reinforcing Rock Mass

为了解决加固岩体预应力锚索拉力松弛的解析计算问题,基于锚索与周围岩体的基本相互作用原理与特征,提出了采用描述锚索力学性质的Hooke体和描述围岩流变力学性质的Kelvin-Hooke体的串联模型,以此来整体描述锚索与围岩之间的相互作用耦合关系.推导出了锚索拉力松弛方程,定量表达了锚索的长期拉力与锚孔间距、锚索弹性模量、围岩的流变参数、锚索直径及其初始拉力等重要因素之间的关系.室内试验和现场测试实例分析结果表明:所提出的计算模型与测试结果较为一致,锚索松弛拉力终值的最大计算误差约为7%,该串联分析模型更具有合理性;锚孔间距、锚索直径与围岩的流变参数对锚索拉力松弛有显著的非线性影响特征.

Based on the interaction mechanism between an anchor cable and rock mass,a series of models that one Hooke body of describing the anchor cable connects in series with one Kelvin-Hooke body of describing the rock mass was proposed to solve the relaxation problem of pulling force of prestressed anchor cables.In light of the model reflecting coupling relation between the anchor cable and rock mass,a formula corresponding to the relaxation effect of the pulling force was derived.It reveals quantitatively the influences of the spacing between the adjacent two anchor holes,elastic modulus of the anchor cable,rheological parameters of rock mass,and diameter of the anchor cable,and initial pulling force on the long-term pulling force.Analysis results of one laboratory and in-situ test example show that the predicted pulling force using the proposed model is identical with the observed one.The maximum error of final pulling force of the prestressed cables between the calculation and observation value is 7%.The proposed model is reasonable.Spacing between the adjacent two anchor holes,diameter of the anchor cable,and rheological parameters of the rock mass have obviously nonlinear influences on the relaxation effect of the cable.