基于三维扫描与打印的岩体自然结构面试样制作方法与剪切试验验证

A method for preparing natural joints of rock mass based on 3D scanning and printing techniques and its experimental validation

无法大量制作表面形态完全一致的含自然结构面的剪切试样一直是困扰岩石结构面力学试验深入研究的难题之一。借助最新发展的3D打印和表面快速扫描技术,提出了岩石自然结构面试样制作新方法。该方法采用三维扫描仪获得岩石自然结构面表面形态的高精度点云数据,然后通过逆向工程软件重构自然结构面的表面形态和含自然结构面的虚拟剪切模型,进而通过3D打印技术制作含自然结构面的PLA(绿色环保材料聚乳酸)塑材模具,最后借助PLA结构面模具在制样盒内通过相似材料浇筑成型出剪切试样,从而实现批量制作结构面形貌完全一致的相似材料结构面剪切试样,满足多种组合试样方案下岩石自然结构面的深入分析。采用这一方法针对3种岩石自然结构面进行了批量制作和剪切试验测试表明:(1)浇筑制作成试样的结构面表面高程与原始结构面高程之间的误差分析显示,岩石自然结构面可以高精度地复制到剪切试样中;(2)相同剪切试验条件下多个剪切试样的剪切位移-剪切力曲线的重合度非常高,表明制作的结构面剪切样的一致性好且试验结果离散性小;(3)通过剪切结构面试样在剪切前后的表面形态扫描分析发现,相同试验条件下自然结构面的剪切破坏形态具有非均匀性。

Failure to prepare the rockmass sample with joints of the same surface morphology as those of natural joints has long been infesting the mechanical experiment on the structural surfaces of rock mass. With the latest development of the 3D printing technique and the rapid surface scanning technique, a new method is developed for producing the joint specimens containing the joint surfaces similar to those of natural rockmass. In the proposed method, a 3D scanner is first used to obtain the point cloud data related to the surface topography of joints of natural rockmass; then the virtual specimen model containing natural joints and related surface morphology information is reconstructed, and finally the PLA mould with the joint surfaces is produced using the 3D printing technique. The shear specimens are prepared by pouring the similar material into the PLA mould. Three types of rockmass joint surfaces are copied with the proposed procedure; and a series of measurements and shear tests are conducted on the made joint specimens. The results indicate that： （1） the proposed method can copy accurately the joint morphology from the originally natural joint; （2） among the three types of rockmass joint specimens, the displacement-force curves of the specimens are very close to each other, showing that the consistency of the made specimens containing joint surfaces is satisfied under the identical conditions; （3） by comparing the joint surface contour before shearing to that after shearing, it is found that the shear-induced failure occurs heterogeneously.