Investigation of 3D Printing Sand Core Technology on the Mechanical Behaviors of Soft–Hard Interbedded Rock Masses

Abstract

Three-dimensional (3D) printing has been increasingly applied to experimental research in geotechnical engineering. In this paper, standard cylinder specimens with high and low strength were prepared using 3D-printing sand core technology. The elastic–plastic and rheological mechanical behaviors were experimentally studied. In addition, the similarity and limitations were verified through comparison with natural sandstone, slate, sand–gypsum, claystone, etc. On this basis, a new way to prepare soft–hard interbedded layered rock in geotechnical mechanics was developed. Considering the features of layered rock and the principle of 3D printing, cylindrical and cubic specimens of soft–hard interlayered rock mass with different inclination angles were prepared by controlling the binder content layer by layer. The deformation and strain differences between the soft and hard phases were verified through digital image correlation. In this case, the anisotropic failure evolution mode of soft–hard interbedded rock mass was revealed by the images captured. The structural anisotropy behaviors of 3D-printed soft–hard interbedded rock was also studied. The results agree well with the published experimental and theoretical results. This study introduces a broad prospect of 3D printing sand core technology for future experimental mechanical research on a soft–hard interbedded layered rock mass in geotechnical engineering. This study developed a new method for preparing soft–hard interbedded rock masses based on 3D printing sand core technology. The elastic–plastic and rheological characteristics of 3D-printed soft rock, hard rock, and soft–hard interbedded rock were investigated and compared with a natural layered rock mass. Moreover, the deformation and strain differences between the soft and hard phases were verified from a mesoscopic perspective. The structural anisotropy behaviors and anisotropic failure mode of soft–hard interbedded rock mass were revealed. The results agreed well with the published experimental and theoretical results. Thus, specimens with complex structures, such as soft–hard interbedded rock mass, could be prepared with 3D printing sand core technology. As a result, the mechanical parameters of 3D-printed specimens were close to those of sandy mudstone and claystone rock masses, while the trends of the stress–strain curves of 3D-printed specimens were consistent with natural sandstone rock masses. This study brings a broad prospect for future investigation of the soft–hard interbedded layered rock mass in actual geotechnical engineering.