Research purposes: Based on Bashan tunnel project of Nanning-Yulin railway, a comprehensive advanced geological prediction system suitable for complex geological conditions is established to accurately judge the karst development of tunnel face. Considering the surrounding rock grade, karst type, filling condition and groundwater condition, the treatment measures of karst tunnel arch collapse are studied to ensure the safety of tunnel construction. Based on the comprehensive geological prediction results, targeted treatment of karst is carried out.
Research conclusions: (1) The DK32+713~DK32+723 section of the tunnel is a karst development area. Affected by the contact zone, bedrock fissure water mainly seeps and erodes along the contact zone, and then a fully filled karst cave was formed. (2) The comprehensive advanced geological prediction system suitable for the tunnel has been established, and the shape and scale of karst, the spatial position relationship with the tunnel and the development of groundwater have been proved. The detection results are basically consistent with the field findings. The comprehensive advanced geological prediction with advanced horizontal drilling as the main method and TSP, GPR and geological survey method has good detection effect and high accuracy. (3) Combined with the detection results, targeted measures are taken for karst collapse, and the tunnel passes through the karst development section safely. Through the monitoring and measurement of surrounding rock, the deformation tends to be stable after the tunnel passes through, and the effect is good. (4) For the tunnel in karst area, it is necessary to further strengthen the advance geological prediction, find out the anomalies in advance, and take pre reinforcement measures in time. Functions of advanced geological prediction are made best use of to avoid causing safety accidents. (5) The research result is of guiding significance to the construction of tunnel engineering in karst area.