# Investigation into the Construction Response of Tunnels through Fault: Model Test
## 1 Introduction  
The construction of extralong tunnels, whether mountain tunnels, undersea tunnels, or shield tunnels, will inevitably encounter many fault structures. Table 1 summarizes the cases of construction failures in fault tunnels. These failures often result in a series of tunnel issues, such as large deformation and collapse, in the surrounding rock and supporting structure at the fault area, as shown in Figure 1. These issues can cause immeasurable harm to the tunnel construction process. The shear force generated by the sliding of the upper and lower walls of the fault greatly affects the stability of the surrounding rock of the tunnel. This force can also change the physico-mechanical properties of the rock mass and reduce the overall strength of the surrounding rock. Consequently, the instability of the surrounding rock leads to large deformation when the tunnel passes through the fault. Therefore, it is crucial to understand the deformation response of the surrounding rock and supporting structure to ensure construction safety. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Number** & **Tunnel Name** & **Geographical Location** & **Geological Features** & **Construction Problem** & **References** \\ \hline
1 & Da Liang & & Fractures cut both the north and south sides of the tunnel, causing the structure to be extremely incomplete. The surrounding rock is weak and broken & The surrounding rock underwent significant deformation & [1] \\ \hline
2 & Dayaogou & & The surrounding rock undergoes frequent changes, with three to four different types of rocks found on the same tunnel face & The surrounding rock appeared to have collapsed & [2] \\ \hline
3 & Daxiangling & & The tunnel passes through 19 faults or structural fracture zones, and the rock mass is highly fragmented & The surrounding rock underwent significant deformation, and there were numerous landslides & [3] \\ \hline
4 & Xuefengshan & & The tunnel actually passes through 18 fault fracture zones. & The surrounding rock was extremely fractured and collapsed during construction & [4] \\ \hline
5 & Changliangshan & & The tunnel passes through numerous faults, where the rock mass is fractured and contains a high mud content & The surrounding rock was extremely fractured and collapsed during construction & [5] \\ \hline
6 & Zhangjiawan & & The tunnel is affected by three major fault fracture zones & There was significant settlement of the vault, and the surrounding rock collapsed & [6] \\ \hline
7 & Xianglushan & & The tunnel passes through over four wide fault zones, with the tectonic rocks in these zones being weak and poorly cemented & The middle section of the side wall exhibited significant deformation, and its destructive behavior was prominent. & [7] \\ \hline
8 & Yonglian & & The tunnel passes through over five fault-fractured zones, where the rock masses in these zones are weathered and consist of numerous types & There are many large-scale collapses occurred in the tunnel & [8] \\ \hline
9 & Dongtianshan & & The tunnel passes through a fault & The uneven settlement of the tunnel foundation caused significant deformation of the initial support, ultimately leading to a serious collapse accident & [9] \\ \hline
10 & Yesanguan & & The tunnel passed through multiple fault fracture zones and the surrounding rock was weak & The vault experienced significant settlement deformation, resulting in garious deformation and damage to the primary support structure & [10] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistical table of tunnel fault fracture zone issues. Several factors can affect the mechanical response of a fault tunnel. Scholars have identified that the relative movement of the hanging wall and footwall [11; 12; 13], fault dip [14; 15; 16; 17], fault lithology [18; 19], fault thickness [20], cover depth of the tunnel [21; 22], and relative position of the fault and tunnel [23; 24; 25] can all lead to different tunnel deformation mechanisms that affect construction safety.