Comprehensive Geophysical Investigation and Analysis of Lining Leakage for Water-Rich Rock Tunnels: A Case Study of Kaiyuan Tunnel, Jinan, China

Leakage of lining structure is one of the main geological disasters of the tunnel, which brings heavy economic losses and casualties. Aiming at the problem of lining leakage of the Kaiyuan Tunnel in Jinan, this research has carried out a geological survey, conducted statistics, and classification of the leakage situation of the Kaiyuan Tunnel. The causes and main control factors of various types of seepage are analyzed. To locate the leakage accurately, electrical resistivity tomography, transient electromagnetic method, and ground penetrating radar are used to carry out comprehensive geophysical exploration. Two catchment zones and fractured zones are determined based on the existing geological topographic maps, geological profile maps, and geological analysis results. Transient electromagnetic detection results coincide with the known fractured zones, which confirms the existence of fractured zones and defines the scope of fractured zones. Moreover, the detection results based on ground penetrating radar show that the main adverse geological conditions inlining and surrounding rock are water diversion area, hidden water diversion area and surrounding rock fragmentation area. Subsequently, three kinds of grouting material, ultra-fine cement, ordinary Portland cement, and polymer cement, were selected for seepage control of the 800–900 m and 1310–1330 m test sections for plugging treatment. The grouting effect was analyzed and evaluated based on ground penetrating radar detection and field working conditions. Especially, the grouting radar detection shows that the grouting effect of polymer cement slurry is ideal, the grout in the water conduction area is basically filled, and the lining cracking and damage have been significantly repaired and improved. This paper verifies the accuracy and good feasibility of the interpretation criteria of comprehensive geophysical detection for typical lining defects, which can be popularized and applied in relevant tunnels and underground projects.