For the karst tunnel with pipeline cavity in the surrounding rock

it is very easy to accumulate high water pressure in the pipeline cavity due to the influences of heavy rainfall on the surface and groundwater

which will lead to lining cracking

water leakage and water gushing diseases. To explore the influence of high water pressure on the lining structure

a model test of pipeline karst tunnels under high water pressure was carried out

and the internal force characteristics of tunnel lining under the influence of cavity position and head height were studied. Based on this

the numerical calculation model of extended working conditions was established. The effects of cavity diameter

cavity position and water head height on the lining structure were further explored. The results show that the inner side of the lining in contact with the cavities bears larger positive bending moment

when there are karst cavities around the tunnel

which are the most unfavorable stress positions of the lining. The internal force of the lining increases greatly

with the increase of cavity diameter and water head height in the cavity. The location of the cavity affects the internal force distribution of the lining

and the anti-water pressure capacity of the lining is the smallest

when the cavity is located at the tunnel vault. The research results can provide reference for the structural design and safe construction of pipeline karst tunnels.