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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。
The roof rock of coal seam is used as anchoring base, the steel wire is used to simulate the steel bar and the thin strip is used to simulate the steel strip, and the three-point bending test of the anchoring body is carried out. The comparison is made with the conventional test piece. The results show that the tensile strain of the lower surface increases faster than that of the upper surface due to the difference of compressive strength and tensile strength of rock, and the crack first develops on the lower surface and gradually increases. Anchoring test pieces improve the mechanical properties of the rock in the anchoring area because of the anchor rod, and the strip and the anchor rod share a certain tensile stress, and the bending resistance of the anchored test piece is enhanced. The cross-section stress state of the specimen can be divided into three stages in combination with the failure process. The first stage is the elastic stage. The second stage is the crack initiation and propagation stage. The bearing capacity of the rock gradually deteriorates. The tensile stress gradually transfers to the steel belt. The bending strength of the specimen has greatly improved; the third stage is the failure stage, the anchor is out of stick, the deflection continues to increase, and the bearing capacity of the specimen tends to be stable.