基于3D打印的类节理岩体模型及力学特性

Investigation of preparation of jointed models and the experimental evaluation of mechanical behavior based on 3D printing

  • 摘要: 节理裂隙构造分布对岩体变形与破坏特性具有关键控制作用,厘清节理构造及岩体力学特性对于指导工程稳定性具有重要意义。3D打印技术在岩石力学方面的应用为节理岩体力学特性研究提供了有效手段。基于3D打印技术提出一种节理岩体制备方法,开展单轴压缩测试分别分析了实心试样、RDFN模型和DFN试样的变形特性及破裂模式,讨论了透明硬水晶与PLA材料在预制节理岩体力学特性分析的适用性,对比了冷冻处理下透明硬水晶材料的力学变化。研究发现:基于PLA树脂的3D打印材料在单轴压缩条件下发生了膨胀扩容,并呈现显著的塑性变形特征,与岩石的力学性质有较大差异;硬水晶材料的破坏模式为明显的"X"共轭剪切变形破坏特征,峰前应力-应变曲线特征与岩石接近,含裂隙试样的表现为沿近似45°斜面的压剪破坏;裂隙网络的存在会显著降低类岩体模型的抗压强度,粗糙RDFN的类节理岩体模型强度高于直线型DFN类节理岩体模型,试样发生斜截面剪切破坏时,节理模型增强了裂隙系统的锁固效应;类节理岩体表现出一定的尺寸效应,并受PLA材料高塑性特性影响;承压强度实心试件总体来说最强,RDFN模型次之,DFN模型最小,3类模型强度存在一定的尺寸效应特征。冷冻处理后,实心水晶模型试样的峰值强度降低约56.57%并呈现一定脆性特征,含节理模型的破坏模式为单斜面剪切破坏,开挖含孔洞裂隙体产生劈裂破坏,顶部及底部产生微裂纹,表现出与岩体相近的结构控制型破坏模式,表明开展冷冻条件下的类节理岩体模型处理可以用来开展节理岩体力学特性研究。

     

    Abstract: The existence and distribution of joint structures dominate the deformation and fracture characteristics. The research on the complex joint network of rocks is crucially significant for the stability analysis of rock engineering. The application of the 3D printing technology provides an efficient approach to the study of the mechanical behavior of jointed rock masses. A 3D printing-based fracture rock mass model preparation method was proposed to study the influence of the fracture network on the jointed rock mass. The deformation and failure modes of RDFN, DFN, and no-crack models of varied specimen sizes subjected to uniaxial compression were compared and analyzed. The feasibility of the crystal glue and PLA printed materials on the jointed rock specimen was discussed considering the frozen effect on the crystal specimens. According to the result, the PLA material expands under uniaxial compression pressure and extends plastically, which differs from the natural rock specimens. For solid specimens, the failure mode shows an obvious X-shape shear failure. The material of crystal glue shows plastic deformation, which can be used to simulate rock mass in the pre-peak stage. The specimen with cracks exhibited compression-shear failure along an inclined section of approximately 45°. The existence of joint networks decreased the compressive strength, and the compressive strength of the RDFN model was higher than that of the DFN model. An apparent lock segment effect on the compressive shear process of the jointed specimens was obtained. The Size effect of the jointed specimens under the influence of a 3D printed fractures network was examined. The high plasticity of PLA printed material in the post-peak stage limits the feasibility of the 3D printed models. The compressive strength of the solid specimen reaches the maximum value, followed by the rough RDFN specimen, and the straight DFN specimen reaches the minimum. Under the influence of low temperature, the intact model behaved ductile with the compressive strength of the frozen specimen was reduced to about 56.57%. The failure mode of the DFN model was a single-slope shear failure and the hole model was a split failure, which can simulate the fracture pattern of jointed rock masses under the freezing treatment.

     

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