Numerical Analysis of Grouting of Water-Enriched Karst Highway Tunnel Based on Critical Water-Enriched Height

The occurrence state of groundwater in a karst area has a significant impact on the tunnel lining structure. The impact on the groundwater is more significant during construction. This paper used numerical simulation to study the grouting reinforcement range of the Liaoshan Tunnel. This was based on the critical water rich height. Under Grade IV and Grade V surrounding rock, the critical points of grouting reinforcement were 230 m and 240 m deep, respectively. The vertical and horizontal stress and seepage flow of the tunnel arch crown and invert decreased as the circumferential grouting reinforcement range increased. In the case of no grouting reinforcement, 1/4 circumferential grouting reinforcement, 1/2 circumferential grouting reinforcement, and all circumferential grouting reinforcement, the seepage flow was 7 m(3)/dm, 4 m(3)/dm, 3 m(3)/dm, and 0 m(3)/dm, respectively. With Grade V surrounding rock, when the groundwater level was 260-270 m away from the tunnel arch crown, two schemes could be adopted: 1 m radial grouting reinforcement and 1/2 circumferential grouting reinforcement. The results have guiding significance for developing a construction scheme of a karst water rich tunnel.