加锚岩石抗弯特性试验研究

采用煤层顶板岩石作为加锚基体，用钢丝模拟锚杆，薄钢片模拟钢带，对加锚体进行了三点弯试验，并与常规试件进行对比分析。结果表明，因岩石抗压与抗拉性能的差异，试件在弯曲过程中，下表面拉应变的增长速度大于上表面压应变的增长速度，裂纹最先在下表面产生并逐渐向上发展。加锚试件，因锚杆改善了锚固区域岩石的力学性能，且钢带与锚杆共同承担了一定的拉应力，锚固试件抗弯能力有所增强。试件截面应力状态可以结合破坏过程分为3个阶段，第1阶段为弹性阶段；第2阶段为裂纹产生与扩展阶段，岩石承载能力逐渐劣化，拉应力逐渐向钢带转移，岩石裂纹发展受限，试件抗弯能力有较大提升；第3阶段为破坏阶段，锚杆失黏，挠度持续增加而试件承载能力趋于稳定。

Experimental study of flexural behavior of anchored rock

With rock sample of coal seam roof as matrix and steel wire as bolt and steel sheet as steel strip, anchored rocks have been experimented by means of three-point-bend. Testing results show that: as the differential properties on compressive and tensile of rock，the speed of tensile strain growth is greater than that of compressive and cracks begin to extend on the lower surface of rock and gradually propagate upward in the bending process. The flexural behavior of bolt anchored specimen has been enhanced, while the mechanical properties of rock are improved in anchorage zone, and a certain amount of tensile stress is shared by steel belt and bolt. The cross section stress distribution of specimen could be divided into three stages in accordance with the failure process. The first is elastic stage. Crack generation and propagation is the second stage. The bearing capacity of rock start to deteriorate, and tensile stress gradually shifts to the steel belt, bearing capacity of anchored increases dramatically because crack propagation of rock is limited. The third is failure stage, bolt lost function, deflection increases while bearing capacity of the specimen tends to be stabled.