\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Number** & **Rout Name** & **Tunnel Name** & **Length** & **Distress Location** & **Distress Condition** \\ \hline
1 & Shenmu- & Shekoumao & 5804 & Arch wall, tunnel & Cracks occurred on the arch wall; ponding in the tunnel bottom; cracking of tunnel bottom and bed & \\
2 & Shenmu- & Huojialiang & 4722 & Tunnel foundation, ballast bed & Mud pumping of foundation; subsidence of ballast bed \\
3 & G312 & Qijiadashan & 860 & Lining, pavement & Cracks occurred on the pavement and lining \\
4 & Baotou-Xi’an & Maotianshan & 14,915 & Ballast, ballast bed & Larger deformation occurred on the ballast bed; \\
5 & Baotou-Xi’an & Tongmushi & 8282 & Tunnel foundation & Water emitting caused by cushion cracks \\
6 & Baotou-Xi’an & Jiuyanshan & 9353 & Ballast bed & Mud pumping induced by cushion cracks \\
7 & Baotou-Xi’an & Sizehe & 7655 & Ballast bed & Mud pumping of foundation; subsidence of ballast bed \\
8 & Taiyuan- & Hengshan & 11,448 & Tunnel foundation & Cracks occurred on the cushion \\
9 & Taiyuan- & Xingwangmao & 11,055 & Tunnel foundation & Cracks occurred on the cushion; mud pumping & \\
10 & Xi’an-Yan’an & Lingjiachuan & 1137 & Tunnel foundation & Water emitting caused by cushion cracks \\ \hline \hline \end{tabular} Note: (Unit: m).  
\end{table} 
Table 1: Statistics of diseases at the bottom of some operating loess tunnels in China [5]. model, [PERSON] (2021) studied the stability of the tunnel face crossing the fault fracture zone with high water pressure. To reveal the influence of the difference in the permeability coefficients of the strata on the distribution of the seepage field near the working face, the tunnel was numerically simulated. A new limit equilibrium model consisting of a trapezoid and a prism is proposed by introducing the geological interface effect. By considering the influence of seepage force and geological interface, the distributed load exerted by the prism on the trapezoid is deduced [14]. When reinforcing the tunnel base, many construction schemes adopt the form of a composite foundation. The composite foundation reinforcement measures can reduce the uplift displacement of the tunnel bottom and the overall settlement caused by water immersion [15]. [PERSON] et al. (2018) studied the reinforcement effect of a high-pressure jet grouting pile on the foundation of deep-buried large-span collapsible loess tunnel through on-site displacement and stress monitoring of the Fujiayao loess tunnel [16]. [PERSON] et al. (2013) analyzed the mechanism of high-pressure chemical mixing pile strengthening loess tunnel base, gave the strength calculation formula of the composite foundation of high-pressure chemical mixing pile strengthening loess tunnel foundation, and established a finite element model for settlement calculation [17]. [PERSON] et al. (2019) carried out a numerical simulation of pile group foundation engineering of a shield tunnel in which the Nanjing Metro Airport Line traversed the Beijing-Shanghai high-speed railway and analyzed the characteristics of horizontal displacement of pile foundation along the bridge deck in the whole traversing process. On this basis, taking the horizontal displacement of a single pile as the evaluation index, the reinforcement effects of grouting reinforcement, longitudinal beam reinforcement and cross support reinforcement, and bored pile reinforcement are compared and analyzed [18]. [PERSON] et al. (2020) take the pile group foundation of the shield tunnel of Shenzhen Metro Line 10 passing through the Guangzhou Shenzhen Expressway Bridge as an example, analyzes the influence of shield tunnel construction on the pile stability by using numerical simulation, and discuss the stress transfer mechanism of the pile foundation during the support and tunneling stages of the shield tunnel [19].