基于3D打印试件的裂隙岩体断裂特性及裂纹扩展特征研究

Study on Fracture Characteristics and Crack Propagation Features of Fissured Rock Mass based on 3D Printed Samples

为探究不同倾角裂隙对岩石断裂特性的影响,本研究基于3D打印技术制备直切槽半圆盘弯曲(NSCB)试件,开展含裂隙岩体Ⅰ型静态断裂特性的试验研究。为探究不同的预制裂隙角度对于岩石断裂特性的影响,本研究基于3D打印技术制备含裂隙倾角的直切槽半圆盘弯曲试件(NSCB),打印好的试件经过固化,烘烤处理后,将其放置在干冰中,待其表面温度达到-30℃时进行准静态三点弯曲试验,该试验揭示了预制裂隙倾角对于断裂韧度、起裂角、断裂能的影响规律。结果表明:含裂隙NSCB试件平均断裂韧度均小于标准NSCB试件,且试件断裂韧度与裂隙倾角成正相关;对于含裂隙的NSCB试件,在β介于0°~90°之间时,起裂角随着裂隙倾角的增大而增大,裂纹拓展路径则表现出明显的“偏折”现象;从断裂破坏的能量角度分析,断裂能随着裂隙倾角的增大而增大。

To study the influence of rock fracture characteristics with different inclination angles,the notched semi-disk bending(NSCB)specimens were prepared based on the 3D printing technology for experiments on typeI static fracture characteristics of rock mass.Specifically,the straight-cut groove half-disc bending specimens(NSCB)with crack angles were prepared by 3D printing technology to investigate the influence of different pre-fabricated crack angles on rock fracture characteristics.Furthermore,the printed specimens were placed in dry ice and subjected to quasi-static three-point bending tests when their surface temperature reached-30℃after the solidification and baking treatments.The experiment revealed the influence of pre-fabricated crack angles on fracture toughness,initiation angle,and fracture energy.The results show that the average fracture toughness of NSCB specimens containing fissures is smaller than that of standard NSCB specimens.The fracture toughness of specimens is positively correlated with the fissure inclination angle.For NSCB specimens containing fissures,the initiation angle increases with the increase of the fissure inclination angle whenβis between 0°and 90°,and the crack propagation path shows a distinct‘deflection’phenomenon.The fissure inclination angle significantly impacts the complexity of the NSCB specimen propagation path.The crack propagation path becomes more complex when the fissure inclination angle and fractal dimension increase.From the perspective of fracture energy,the fracture energy increases with the increase of the fissure inclination angle.