In-situ X-CT scanning and numerical modeling on the mechanical behavior of the 3D printing rock

A better understanding of the heterogeneous mechanical properties of the three-dimensional printing (3DP) sample is vital to advance its utilization in the physical model experiments on engineering applications involving rocks. Three types of 3DP samples were manufactured by adopting binder jetting (BJ) and selective laser curing (SLC) technology with silica sand (SS), the gypsum powder (GP), and coated silica beads (CSB). The mechanical properties and the fracture propagation mechanism in the uniaxial compression test were investigated using the in-situ micro X-ray computerized tomography (X-CT) scanning with a loading system. In addition, corresponding numerical simulation was conducted to investigate the heterogeneous mechanical properties caused by the 3DP process. The results indicated that: 1) Since the strength of the 3DP samples was much weaker than that of the natural rock, the propagation patterns of the cracks after failure was characterized by the regional fracture bands. 2) The failure of the 3DP sample started from the weak cementing, and the 3DP samples also showed heterogeneity in mechanical properties caused by the heterogeneous cementing conditions. 3) The fitted Young's modulus of the 3DP SS, GP, and CSB were 0.4GPa, 0.25GPa, and 0.53GPa, which showed a bit lower than that of the experimental data. 4) The calculated peak strength of SS, GP, and CSB were 6.21 MPa, 9.14 MPa, and 8.15 MPa. The cohesive force of the weak cementing part was about half of the normal cementing part and the re-sidual cohesive force was about 0.2 times of that before failure.