3D打印技术在岩体物理模型力学试验研究中的应用研究与展望

传统的岩石取样方法以及模具浇筑常受到人工操作误差及取样内部结构复杂差异大的影响，导致岩石试件获取的周期时间长，精度低，造成试样的力学试验结果离散性大。3D打印技术具有精度高、周期短、打印材料多样化等优点，考虑到岩石力学研究受到试件各向异性、结构面复杂、随机性高及试件制备存在误差等因素影响，为寻求能够模拟天然煤岩的3D打印材料，选取了聚乳酸塑料(PLA)、光敏树脂材料SLA600及Vero White Plus，以及覆膜砂粉末材料4种材料制备标准力学试验试件进行单轴压缩试验，获取了4种材料的3D打印试样的力学参数及应力-应变曲线，并对比分析了它们与煤岩的表观破裂模式的相似性。结果表明：光敏树脂材料Vero White Plus与砂岩岩样的峰值强度、杨氏模量、泊松比及应力-应变曲线整体趋势相近；覆膜砂材料与所选煤样的峰值强度、杨氏模量及应力-应变曲线相近；表观破坏模式方面，PLA材料未发生与煤岩相似的脆性破坏；两种光敏树脂材料均发生了拉张与剪切破裂，其中SLA600材料表现出局部膨胀性，Vero White Plus材料与SLA600相比更适合模拟高强度的脆性硬岩；而覆膜砂3D打印试件的破裂特征及力学特性与低强度软岩相似，可作为低强度的脆性煤体的3D打印相似材料。

Shale gas revolution

Traditional rock sampling methods and mold casting are often affected by manual operation errors and complex internal structure differences. They can result in long cycle time and low accuracy of rock specimen acquisition, as well as large discrete mechanical test results of samples. 3D printing technology has the advantages of high precision, short period and diversified printing materials. The past rock mechanics research is affected by factors including anisotropy of specimen, complex structural plane, high randomness and specimen preparation error. We seek 3D printing materials that can simulate coal and rock with different hardness. We select the plastic poly(lactic acid)(PLA), photosensitive resin material SLA600 and Vero White Plus, four kinds of materials and coated sand powder materials. We prepared standard mechanical test specimens in uniaxial compression test, obtain the mechanical parameters of four kinds of materials and the stress strain curve, and analyze the four kinds of materials and fracture mode of the coal and rock. The results show the follows. At the peak strength, Young's modulus, Poisson's ratio and stress-strain curves of the photosensitive resin Vero White Plus are similar to those of the floor sandstone. The peak strength, Young's modulus and stress-strain curves of the coated sand are similar to those of the coal samples. In terms of apparent failure mode, PLA material has no similar brittle failure to coal rock. Tensile and shear fracture occurred in both photosensitive resins. SLA600 exhibits local expansibility. Vero White Plus is better suited to simulate brittle hard rock with high strength than SLA600. The fracture characteristics and mechanical properties of the coated sand 3D printing specimen are similar to those of low-strength soft rock, which can be used as 3D printing similar material of low-strength brittle coal.