## 3 Analysis of Deformation and Failure Characteristics of Deep Gob-Side Entry  
The reasons for the deformation of deep roadway are diverse, involving geological conditions, local structures, the design and construction of the tunnel itself, etc. The on-site investigation of the deformation of the roadway along goal in deep soft coal seam in Zhujidong Coal Mine and the roadway in Dongtan Mine under similar conditions found that, due to the large depth of the working face and the low strength of the raw coal, the roof and side of the roadway have deformed to different degrees, and the phenomena of steel strip collapse and anchor bolt failure have appeared in some sections of the roadway. As shown in Figure 2.  
According to the on-site investigation of the roadway along the goal in Zhujidong Coal Mine, the following reasons are the main causes. 1. The roadway section is large, the roof strength is low, and it is difficult to set up top coal support. The excavation cross-sectional area of the roadway along the goal is close to 20 square meters, the roadway span is large, the roof is prone to flexural deformation, and the probability of roof rock separation, sinking, and collapse increases. The overall strength of the direct roof is low, mainly due to the complex rock properties of the direct roof and the development of cracks, thus greatly reducing the stability of the roadway surrounding rock, and part of the roof has netted phenomenon, which is difficult to support. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Construction** & **Trend (\({}^{\circ}\))** & **Tendency (\({}^{\circ}\))** & **Dip Angle (\({}^{\circ}\))** & **Falling Head (\({}^{\circ}\))** \\
**Name** & **Trend (\({}^{\circ}\))** & **Tendency (\({}^{\circ}\))** & **Dip Angle (\({}^{\circ}\))** & **Falling Head (\({}^{\circ}\))** \\ \hline DF326-4 & 43 & 313 & 44–64 & 1.2 \\ DF326 & 13–37 & 283–307 & 30–60 & 2.2 \\ DF326-1 & 11–25 & 101–115 & 57–65 & 2–3.5 \\ DF326-2 & 20 & 110 & 42 & 0.7 \\ DF327-1 & 19–42 & 109–132 & 37–65 & 1.1–6.0 \\ DF327 & 24–47 & 114–137 & 45 & 5.0 \\ DF327-4 & 41–72 & 131–162 & 43–63 & 1.0–3.0 \\ DF319-1 & 40 & 310 & 65 & 1.3 \\ DF319-2 & 46 & 136 & 59–70 & 1.3 \\ DF319-5 & 11 & 101 & 57 & 1.0 \\ DF319 & 1–25 & 271–295 & 45 & 2–2.5 \\ DF322-1 & 15 & 105 & 45–80 & 1.7 \\ DF326-3 & 80 & 170 & 75 & 1.2 \\ DF327-3 & 15 & 105 & 80 & 1.5 \\ DF327-5 & 42 & 132 & 47–59 & 2.0 \\ DF322-1-1 & 162 & 252 & 41 & 1.6 \\ DF322-2 & 19 & 109 & 40 & 3.0 \\ DF322-2 & 85 & 175 & 80 & 2.0 \\ DF322-3 & 18 & 108 & 75 & 1.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Fault parameters of 1321 (1) working face. The size of the coal pillar is small, the coal quality is relatively soft, and it contains interlayers. The size of the coal pillar left is small, with a width of 7 m, and the coal quality is weak, soft and broken. The asymmetric deformation of the two sides is obvious, especially the side squeezing of the small coal pillar is serious. The coal seam contains interlayers, and the roadway excavation causes the interlayers to be exposed, and the weak surface is easily disturbed. The depth of the working face is large, the geo-stress is high, the existing support control effect is poor, and the deformation of the roadway is large. The average buried depth of the roadway is 950 m. The long-term rheology of the roadway under high stress will increase the deformation rate of the roadway and affect the stability of the roadway surrounding rock. Under the existing support scheme, the support components have collapsed and failed, losing the surface protection ability, and the investment and loss of support materials are serious. Deep rock formations usually have high ground stress, and the rock strength and integrity are relatively poor, which is easy to deform. For example, weak rock formations such as mudstone and shale have weak bearing capacity and are prone to large deformation under the influence of mining. In summary, this type of roadway deformation is serious, and roof control is difficult.