单/多离层作用下锚杆受力特性分析

Force characteristic analysis of bolt under single and multiple bed separation

巷道围岩由于变形的不协调常常会产生单个或多个离层。根据岩层相对移动时拉拔载荷对锚杆的作用机制,对单个离层产生的锚杆附加应力建立弹塑性力学模型,讨论了弹性状态下离层对锚固体荷载的影响,随着离层进一步扩展,锚固体界面进入弹塑性阶段,基于剪切滑移模型,确定出离层左右两侧的滑移范围。总结出离层作用下锚杆受力全过程分为5个阶段:全弹性、单侧弹塑性、两侧弹塑性、一侧全滑移而另一侧滑移范围增大、全塑性直至锚杆承受极限拉拔荷载而破坏。采用模型试验数据对岩体离层-锚杆轴力曲线特性进行对比验证,结果表明,计算值与实测值吻合较好。根据应力叠加原理,推导出多离层情况下锚杆的应力求解公式,得出应力分布为多峰曲线。通过实例对离层值、离层位置做了参数分析,离层对锚杆的荷载影响应在今后的锚固设计中予以考虑。

The roadway surrounding rock often produces single or multiple bed separation due to deformation incoordination. Based on the mechanism of bolt pullout force during the relative movement to the strata, an elastic-plastic mechanics model of additional stress occurred by bed separation was established. The influence of bolt loading caused by bed separation in elastic state was firstly discussed. The interface of anchorage body will enter elastic-plastic stage under further expansion of bed separation. The sliding ranges on both sides of the bed separation were determined through the two-stage linear function shear slide model. Loading process of the anchorage body under the bed separation function was divided into four general stages, which included elastic stage, one side elastic-plastic stage, two sides elastic-plastic stage, one side sliding further with one side sliding all stage, and both sides sliding all stage. The axial force distribution during bed separation was verified by experimental results. The results show that calculated value has good agreement with the measured value. The bolt stress distribution caused by the multiple bed separation was summarized according to the superposition principle. The multiple peak curves of stress distribution were proved. Finally, the parameter analysis of bed separation value location was made through an example. The influence of bed separation on bolt loading should be considered in future anchorage design.