Study on Model Structure and Mechanical Anisotropy of Columnar Jointed Rock Mass Based on Three-Dimensional Printing Method

The natural structure of columnar jointed rock mass (CJRM) is complex because it was formed during the cooling process of volcanic rock. In CJRM, both the structures of columns and columnar joints are oriented, and the exact mechanical properties are difficult to obtain due to the lack of testing samples that correspond to natural rock masses. Therefore, this brings challenges for underground engineering construction related to CJRM. The reconstruction of CJRM is an effective method that can be used to resolve this problem. However, using an artificial method means that it is difficult to consider the detail of structures, such as irregular columns, columnar joints, and microcracks in columns. With the development of 3D printing (3DP) technology, a useful method for the accurate reconstruction of CJRM has been provided. In this paper, based on laboratory and in situ tests, the structural characteristics and mechanical properties of CJRM in Baihetan Hydropower Station will be investigated. Then, based on the accurate structural reconstruction of CJRMthat considers the similarity constant between in situ and laboratory tests, the mechanical anisotropy and failure modes of 3DP CJRM specimens will be investigated. The results show that 3DP is an effective method for reconstructing the structures of CJRMand that it is necessary to consider the detail of the structures, such as the irregularity of columns, columnar joints, and microcracks. In addition, the unfavorable loading angles between the axis of the column and loading direction were obtained. The 3DP results presented in this paper could provide a reference to help understand the structural characteristics of CJRM. (C) 2020 American Society of Civil Engineers.