硬岩树脂锚杆锚固体岩爆破裂演化试验研究

Experimental Study on Rock Burst Fracture Evolution of Resin Bolt Anchoring Body in Hard Rocks

针对岩爆巷(隧)道树脂锚杆锚固机制研究的不足,利用真三轴加卸载试验系统,开展了两种加载模式下的具有岩爆倾向性的树脂锚杆锚固硬岩试样在一侧约束情况下的双轴压缩试验。分析和探讨了树脂锚杆锚固体岩爆破裂演化及锚固控制。结果表明,在逐级连续加载模式下,锚固体试样产生了小幅度应力降,没有垫板约束的部分可见明显裂纹并呈现层裂现象,观察锚固体内部断面发现锚固体本身基本完好;在逐级断续加载模式下,试样发生整体成层爆裂,小直径锚杆发生断裂,随着锚杆直径的增大,锚固体在控制层爆方面的效果越明显,可用岩爆控制的锚杆组合梁理论来解释其锚固机理;锚固体呈现出比较小的应力松弛现象,是试样内部能量传递、吸收和耗散变化调整的结果,在加载后期一旦应力松弛过程存在非弹性变形极易诱发岩爆;两种加载模式下树脂锚杆锚固体破裂演化不同,原因在于锚杆锚固体内部能量传递和吸收的程度不同。

Aiming at the shortages of mechanism study for resin bolt anchoring body in the roadways（tunnels） with rock burst, based on the true triaxial loading and unloading test system, the hiaxial compression tests were carried out on the hard rock with the rock burst tendency and anchored by resin bolt anchoring under two loading modes and constraint of one side. The rock burst fracture evolution and anchoring control of resin bolt anchoring body were analyzed and discussed. The results were obtained as follows. Firstly, under the continuous loading step by step, the anchoring body sample produced a little stress drop, which presented obvious cracks and slabbing phenomenon in the place without the constraint of base plate. Through observing the internal fracture surface, it was found that the anchoring body was basically complete. Secondly, under the interrupted loading step by step, the anchoring body sample was spalling as a whole, and the bolts with small diameter were broken. With the increase of bolt diameter, the anchoring body had a more obvious effect on the layer blasting control, and its anchoring mechanism could be explained by the theory of bolt composite beam of rock burst control. Thirdly, the anchoring body presented small stress relaxation phenomenon, which resulted from the adjustments of internal energy transmission, absorption and dissipation. And once the stress relaxation process exists non-elastic deformation at the later loading stage, the rock burst would be very easily induced. Moreover, the fracture evolution of resin bolt anchoring body was different under the two loading modes, because the degrees of energy transmission and absorption in bolt anchoring body were different.