单轴压缩下加锚裂隙类岩石试块裂纹扩展试验及PFC^(3D)模拟  

Experimental study and PFC^(3D) simulation on crack propagation of fractured rock-like specimens with bolts under uniaxial compression

作　　者：武东阳 蔚立元[1] 苏海健[1] 吴疆宇 刘日成[1] 周键 WU Dong-yang;YU Li-yuan;SU Hai-jian;WU Jiang-yu;LIU Ri-cheng;ZHOU Jian(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221116

出　　处：《岩土力学》2021年第6期1681-1692,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51704279,No.51979272,No.51579239)。

摘　　要：为探究锚杆对裂隙岩体的锚固效应及其对裂纹扩展的影响,分别制作裂隙倾角为15°、30°、45°、60°、75°以及90°的无锚和加锚类岩石试块,利用MTS816岩石伺服试验机进行单轴压缩试验,并采用声发射和数字照相技术对裂纹扩展过程进行同步监测和记录。此外,使用颗粒流软件PFC^(3D)进一步研究不同锚固角对裂纹扩展的影响。结果表明:锚固体的峰值强度、弹性模量以及起裂应力较无锚试块均有提高。锚杆的存在降低了拉伸裂纹萌生和扩展时的应力强度因子,能够有效限制拉伸裂纹的萌生和扩展,并且抑制剪切裂纹的出现。拉伸裂纹的萌生和扩展过程可分为初始阶段和加速阶段,加锚试块预制裂隙两端特征点的位移明显小于无锚试块。根据PFC^(3D)模拟结果,锚固角β=45°时,锚杆锚固作用最明显,随着锚固角度b的增加,拉伸翼裂纹发育程度先增高后降低,预制裂隙试块破坏模式由剪切破坏转为拉剪复合破坏,再转变为剪切破坏。该研究结果可为分析岩体工程的稳定性提供一定的参考。In order to investigate the anchoring effects of the bolts on the jointed rock mass and its influences on crack propagation, the unanchored and anchored rock-like specimens with joint angles of 15o, 30°, 45°, 60°, 75° and 90° were made. The MTS816 was used for uniaxial compression test, and the acoustic emission(AE) and digital image correlation technology(DIC) were used to monitor the crack growth. In addition, the particle flow code software PFC^(3D) was used to study effects of different anchoring angles on crack propagation. The results show that the peak strength, peak strain and cracking stress of the anchorage unit are improved compared with the unanchored specimens. The existence of bolt reduces the stress intensity factor during the crack initiation and propagation of the tensile wings, which can limit the initiation and propagation of tensile cracks effectively. Moreover, the occurrence of shear cracks can be inhibited. The process of the tensile crack propagation can be divided into initial stage and acceleration stage. The displacement of the characteristic points of the specimens with bolts is smaller than specimens without bolts. According to the PFC^(3D)simulation results, the anchoring effect is the most obvious when the anchoring angle β is 45°. With the increase of the anchoring angle β, the development degree of the tensile wing crack first increases and then decreases. The failure mode of the prefabricated fracture specimen changes from shear failure to tensile-shear compound failure, and then to shear failure. The results can provide a reference value for analyzing the stability of rock engineering.

关 键 词：岩石力学 类岩石试块 锚固作用 裂纹扩展 PFC^(3D) 

分 类 号：TU45[建筑科学—岩土工程]