恒定法向刚度条件下吸能锚杆锚固节理岩体剪切特性试验研究

Experimental study on shear characteristics of energy-absorbing bolt anchored jointed rock mass under constant normal stiffness condition

为研究深部岩体工程即恒定法向刚度(CNS)边界条件下吸能锚杆的锚固效果及锚固节理抗剪性能,开展CNS边界条件下吸能锚杆锚固类岩石节理的剪切试验,探究节理面粗糙度(JRC)及锚固深度(h)对类岩石节理剪切应力(τ)、法向位移(δ_(n))、法向应力(σ_(n))、节理面破坏特征、锚杆变形特征的影响规律。结果表明:吸能锚杆可有效提高深部岩体锚固节理的屈服强度及剪切强度,且其提高幅度随着JRC的增大呈现出逐渐增加的趋势,其剪切应力在弹性阶段后产生应力硬化现象。而节理面剪切磨损面积占比随JRC的增加逐渐增大,锚杆的施加使其上涨了20.88%~109.21%。随着锚固深度的增加,节理面的剪切应力、法向位移、法向应力和剪切磨损面积占比均呈现出先增大后减小的趋势,当锚固深度为80 mm时各项指标参数最优,此时锚杆塑性变形段的锚固作用可充分发挥。研究成果为深部节理岩体支护作业的减能增效提供了重要理论支撑。

To explore the shear characteristic of energy-absorbing-bolt anchored rock joints and corresponding bolt performance under constant normal stiffness(CNS)boundary conditions(the condition is associated with deep buried rock mass engineering).We conducted direct shear tests on energy-absorbing bolted rock-like joints.In particular,the tests were performed under diverse joint roughness coefficient(JRC)and anchorage depth(h)to investigate their influence on the deformation characteristics of anchor bolt and mechanical properties of rock joints,such as shear stress(τ),normal displacement(δ_(n)),normal stress(σ_(n))and failure characteristics of joint surfaces.The test results revealed that energy-absorbing bolt effectively enhance the yield strength and shear strength of deep rock joints.The improvement degree progressively increases with a higher JRC value,in which the shear stress first undergoes the elastic period,followed by the stress hardening period.Besides,the shear-induced damage area on the joint surface grows with increased JRC,and it grows by 20.88%–109.21%under energy-absorbing bolt anchored conditions.Moreover,an increase in anchorage depth initially leads to an increase in shear stress,normal displacement,normal stress,and the shear-induced damage area of the joint surface,followed by a subsequent decrease.The optimal values for these properties were observed at an anchorage depth of 80 mm,allowing for the full utilization of the anchorage effect during the plastic deformation stage of the anchor bolt.These findings provide significant theoretical support for reducing cost and improving efficiency in the support of deep rock joints.