加锚多组有序裂隙类岩体单轴破断试验分析

Fracture experiments on anchoring ordered multi-crack body in rock-like materials under uniaxial compression

为研究锚杆对多组有序裂隙岩体的作用机制,以水泥砂浆预制多组有序裂隙类岩体,采用玻璃纤维塑料筋材(GFRP)模拟锚杆,对预制的类岩体进行全长锚固,制作多组不同锚固条件下的试件。将预制试件在RMT-150伺服试验机进行单轴压缩破断试验。根据试验结果提出了主控裂纹的概念,认为主控裂纹的贯通导致了试件强度的弱化。分别从细观上研究了锚杆对多组有序裂隙类岩体主控裂纹的起裂、扩展和贯通影响机制;从宏观上研究锚杆对多组有序裂隙岩体峰值强度、残余强度以及抗变形能力的影响。研究发现:锚杆锚固后多组有序裂隙类岩体主控裂纹由纵向—倾斜—横向贯通为主的扩展、贯通模式转变为横向—纵向—倾斜的模式,主控裂纹路径更长且贯通过程受到锚杆锚固限制,具体表现为锚杆锚固改变了裂纹尖端的应力强度因子使得类岩体试件抗变形能力更大、试件的峰值强度和残余强度更高。但并非加锚密度越大,类岩体强度越高,适当的加锚密度才能获得更好的支护效果。

In order to study the anchoring mechanism of bolts on the ordered multi-crack body, the full-thread glass fiber reinforced plastic （GFRP） is taken as anchor bolts to fully grout the multi-crack body made from cement mortar to prefabricate test pieces under different anchor conditions. The fracture uniaxial compression tests on these pieces are performed using the RMT-150 servo testing machine. According to the results, the concept of the master crack is proposed, and it is recognized that the strength weakening of the ordered multi-crack body is caused by the perforation of master crack. The work mechanisms of the anchor bolts on the crack generation, expansion and perforation of multi-ordered crack rock-like body are studied from the microscopic aspect, and their effects on the peak strength, residual strength and deformation resistance are investigated from the macroscopic aspect. The result shows that the perforation pattern of the ordered multi-crack rock-like body is changed by the anchor bolts from the longitudinal-incline-horizontal pattern to the horizontal-longitudinal-incline one. The master cracks have longer perforation path and are limited by the anchor bolts. It is specifically indicated that the stress intensity factor of the pieces is changed, and the resistance to deformation, peak strength and residual strength are enhanced after anchored by bolts. However, it is not the situation that the more anchor bolts, the more strength of the ordered multi-crack rock-like body, that is, an appropriate density of anchor bolts will get a better support effect.