Ground-tunnel geological prospecting and treatment methods of small-diameter TBM crossing shallow buried water-rich tunnel: A case study

Water inrush disasters occurred many times when the small-diameter TBM of Yinchaojiliao Project passed through the shallow water-rich section. The effective detection and timely treatment of the water structures ahead of the tunnel face of small diameter TBM is very important to ensure the safe tunneling of TBM. In order to avoid the recurrence of water inrush disaster, the ground-tunnel geological prospecting and treatment methods is put forward. The ground-tunnel prospecting methods include the ground ERT and the tunnel resistivity are established. The ground electrical resistivity tomography (ERT) is used to detect the shallow water-rich tunnel section of small-diameter TBM in advance, and the resistivity range ahead of the tunnel face is obtained, which provides an initial model for the data inversion of tunnel resistivity method. Through the detection results of tunnel resistivity and ground ERT methods, the position of water-bearing structures ahead of the tunnel face is comprehensively judged on the basis of geological analysis, which provides the scope and depth of treatment for small-diameter TBM crossing shallow water-rich tunnel. The ground grouting is used to grout and plug the water-bearing structures range and depth delineated by the advanced detection. At the same time, the chemical grouting is used to plug the water outlet point in the tunnel. Through the above measures, the small-diameter TBM successfully passed through the shallow buried water-rich tunnel section. This paper provides a valuable reference for similar projects through the case study of small-diameter shallow-buried water-rich tunnels in Inner Mongolia, China.