Model Test Study on Water Pressure Distribution Characteristics of Lining Structure in Water-Rich Karst Tunnel

In order to solve lining diseases prone to occur during the operation in tunnels of water-rich karst areas, an optimized drainage scheme was designed based on the Gaojiaping Karst Tunnel of Zhengzhou-Wanzhou high-speed railway, and a model test study was carried out. On the basis of considering the influence caused by different head heights in karst homogeneous stratum conditions, three schemes of no drainage, conventional drainage, and optimized drainage revealed the characteristics of lining water pressure distribution along the longitudinal and cross-sectional directions in water-rich karst tunnels. The results show that the lining water pressures at each monitoring point with longitudinal drainage measures barely change under the two schemes of conventional and optimized drainage. The lining water pressures at the remaining monitoring points decrease as the distance from the circumferential drainpipe decreases. And the longitudinal lining water pressures at each monitoring point between the circumferential drainpipe present an inverted "V" shape distribution. When the conventional drainage scheme is adopted, the optimization effect of water pressure at the foot of the wall achieves the best performance. However, the lining water pressure at the center of the inverted arch is large and the reduction is not obvious. The reduction factor of water pressure is only 0.1-0.15. When the optimized drainage scheme is adopted, not only the lining water pressure at each measuring point is further reduced, but also the reduction at the center of the inverted arch is obvious. The reduction factor of water pressure is up to 0.9. The optimized drainage scheme has a better optimization effect on the lining water pressure and can be targeted at solving the problem of high water pressure at the inverted arch of the tunnel with the conventional drainage scheme. © 2022, Editorial Department of China Railway Science. All right reserved.