# Multi-Means Comprehensive Forecasting Technology for Water Inrush in Long Tunnels
## 4 Analysis and Comparison of Comprehensive Geophysical Exploration Results
### Medium-Range Transient Electromagnetic Detection  
After the pumping was completed on 5 January 2024, transient electromagnetic detection was carried out on the front of the palm surface and on both sides of the left and right walls. A total of 11 measuring points were arranged from the left wall of the vertical palm \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Section** & **Forecast Conclusion** & **Recommended** & **Excavation Reveals the Situation** \\  & & & **Rock Class** & & \\ \hline \multirow{4}{*}{1} & & The P-wave velocity and density are & & The overall integrity of the surrounding \\  & & relatively stable. It is speculated that the & & rock is general, the local surrounding \\  & & integrity of the surrounding rock here is & & rock is broken, there is a local broken \\  & & general, the joint fracture is & & zone, and the groundwater is weak. \\  & & \(\sim\) & weak–developed, the rock is hard, & III–IV & \\  & & the local surrounding rock is & & \\  & & slightly–broken, the local may have & & \\  & & broken zone or weak interlayer, and the & & \\  & & groundwater is weak development. & & \\ \hline \multirow{4}{*}{2} & & S-wave speed suddenly decreased, Vp/Vs & & The overall integrity of the surrounding \\  & & and Poisson ratio increased, and it is & & rock is general, the partial surrounding \\  & & speculated that there is a development of & & rock is broken, there is a partial broken \\  & & \(\sim\) & strong reflection interface and fissure & \\  & & development. The rock mass is broken, & & zone, and the DK0+065 began to enrich \\  & & and bedrock fissure water development, & & the water. \\  & & construction should strengthen safety & & \\  & & protection measures. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Results of seismic elastic wave and seismic analysis. surface to the vertical right wall, and each measuring point completed the data collection of the vertical profile direction of the palm surface (Figure 10). The transient electromagnetic method interprets subsurface conditions by analyzing electrical property distribution patterns across geological strata. In primary formation states, vertical conductivity follows fixed variation trends while maintaining relative horizontal homogeneity. The development of structural features such as faults, fractures, or collapse columns disrupts these inherent electrical anisotropy patterns, regardless of water presence. Such disruptions manifest as conductivity anomalies: Non-aqueous structural zones: elevated resistivity due to reduced conductivity. Water-bearing structures: localized low-resistivity anomalies indicating aqueous phases. Figure 11 shows the pseudo-profile of the results of transient electromagnetic advance detection. In the figure, the horizontal coordinate is the coordinate of the measuring point, the vertical coordinate is the distance along the detection direction, the coordinate system takes the position of the middle point of the tunnel's workforce on that day as the coordinate origin, the right wall of the tunnel is the positive direction of the X axis, and the front of the tunnel is the positive direction of the Y axis. According to the results of YCS400 transient electromagnetic detection, combined with relevant geological and hydrological data, the transverse, horizontal, and vertical depth electrical changes can be determined. As the detection blind area is within 10 m in front of the transient electromagnetic, the effective range of this detection is DK0+055-DK0+000. The following results can be obtained through parallel scanning:  
(1) DK0+040-DK0+010 in front of the workforce in this tunnel prediction section have obvious low resistance areas, and there are suspected to be multiple water-bearing structures. During the construction process, pay close attention to the seepage channels formed by the development of joint cracks, and collect the water from some areas that seep out from the tension cracks in the workforce or side wall.