In China, active faults are widely developed. For tunnels crossing active faults, the permanent deformation caused by fault dislocation usually leads to tensile, torsional-shear, and bending damage, and in severe cases can even cause large-scale offset or overall collapse. For example, in the January 8, 2022, Menyuan M6.9 earthquake in Qinghai, fault dislocation caused severe displacement of the Daliang Tunnel. Therefore, it is necessary to study the tunnel response under fault dislocation in order to guide the anti-dislocation design of tunnels.

The main methods for studying tunnel response under fault dislocation include post-earthquake investigation, theoretical analysis, numerical calculation, and model testing, among which the latter two are the most widely used. In terms of numerical calculation, many scholars have studied the influence of factors such as fault dislocation amount, width, dip angle, and dislocation form on the mechanical response of tunnels, but research on the contact characteristics of the dislocation surface and the dislocation position has rarely been reported. In response to this situation, the Construction Process Mechanics Group of the Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, based on the section of the Tianshan Shengli Tunnel of the Urumqi-Yuli Expressway in Xinjiang that crosses the Bo-A fault, studied the mechanical response characteristics of the tunnel under dislocation of the Bo-A fault through numerical calculation methods, and revealed the influence of the friction coefficient of the dislocation surface and the dislocation position, thereby improving this research field. In terms of model testing, tunnel lining concrete is often simulated using gypsum or its mixtures. When testing its mechanical properties, standard cylindrical specimens (100 mm high, 50 mm in diameter) are generally used, but according to the relevant Chinese concrete specifications, cube and prism specimens should be used to measure mechanical parameters. The mechanical parameters of specimens of different sizes are different. Based on this, the Construction Process Mechanics Group developed a lining similar material with a wide range of physical and mechanical parameters and a compression-tension ratio consistent with prototype concrete through orthogonal experiments, studied the relationship between the mechanical parameters of cylindrical specimens and cube/prism specimens, and prepared corresponding lining similar materials for the Tianshan Shengli Tunnel, which can provide guidance for the preparation of lining similar materials in model tests.

The above research was funded by the National Natural Science Foundation of China (51991393, 52079134), and the results were published in journals such as Environmental Earth Sciences and Engineering Failure Analysis.

Paper link 1: https://doi.org/10.1007/s12665-023-10975-3

Paper link 2: https://doi.org/10.1016/j.engfailanal.2023.107456

Figure 1 Three-dimensional numerical calculation model

Figure 2 Failure diagram of cube/prism specimens

Figure 3 Failure diagram of cylindrical specimens