Abstract: Earthquakes are prone to trigger large collapses during the construction of highway tunnels in fault zones. To avoid casualties and economic losses, the effects of the Wenchuan earthquake on the Yangjiashan Tunnel of the Guanggan highway were examined by using the section at K22 + 624 as an example. A combination of geological field description analysis, geological radar detection techniques and program forward modeling were used in this study. The results showed that the overall properties of the surrounding rock mutated and a strong reflected wave signal formed in the radar waveform pattern within the scope affected by the fault zone after the earthquake. After optimization and post-processing, the establishment of a clear anomaly waveform map was possible; this map was then used to form a conjecture regarding the collapse that may occur in front of the working face. Finally, the forward modeling of this work was undertaken; this can be used effectively to guide the entire tunnel construction process and to obtain better economic returns.