单轴压缩下含层理加锚岩石力学特性研究

Mechanical behaviors of anchored bedding rock under uniaxial compression

为分析锚固方式和层理对加锚岩石力学特性影响规律,采用相似材料预制含层理岩石,室内钻取0°和90°层理标准试件,以45号钢加工而成的螺杆模拟锚杆,分别对试件进行端部锚固和全长锚固,从而得到不加锚杆、端部锚固、全长锚固3种试件,而后在MTS815岩石力学试验系统上对试件进行单轴压缩试验分析其变形、强度特征。结果表明:锚杆可提高岩石的强度,且层理方向和锚固方式影响其对强度的提高幅度。层理相同的加锚试件,全长锚固下岩石的抗压强度提高幅度大于端部锚固岩石;同一锚固方式下,90°层理加锚试件的单轴抗压强度提高幅度大于0°层理加锚试件。锚固方式不同,加锚试件的破坏形式亦有所差别。根据锚固方式不同,可将破坏形式分为剪切拉伸和剪切错断2种。锚固方式对加锚试件锚杆失效模式无影响,二者均表现为岩体与灌浆界面滑脱,但全长锚固与端部锚固所不同的是,全长锚固锚杆与岩石粘结长度更大,粘结强度更高,失效时可带出更多、更厚的岩石碎屑。

The aim of this study is to investigate the effects of anchoring mode and bedding on mechanical properties of anchored rock. Similar materials were used to precast bedding rocks and standard specimens with 0° and 90° bedding were made in the laboratory. Anchor bolts made of #45 steel were applied to perform end anchoring and full-length anchoring, and thus, three kinds of specimens were obtained by end-anchoring, full-length anchoring and non-anchoring, respectively. The uniaxial compressive strength （UCS） and deformation of specimens were obtained by using MTS815 rock mechanical experiment system. The results show that the UCS of rock was enhanced by the anchor. Specifically, the UCS increment was influenced by the bedding direction and anchoring mode. For anchored specimens with the same bedding, the UCS increment of full-length anchored rock was greater than that of the end-anchored rock. For the specimens with the same anchoring method, the increase amplitude of UCS of anchored specimen with 90° bedding was higher than that of the anchored specimen with 0~ bedding. It is found that failure modes of anchored specimens are affected by anchoring types and they are further divided into shearing extension and shearing offset. Failure modes of anchor in anchored specimens are not affected by anchoring methods, and both of anchoring methods slipped between rock mass and grouting interface. However, the differences between the end anchorage and the full-length anchorage are that the latter has longer bond length between the anchor and rock, the higher bond strength was, and the more and thicker rock debris were after failure.