Investigation on the force and deformation of tunnel lining structure under the different local high water pressures

The water-filled caves are extremely detrimental to the stability of tunnel lining structure under the action of local high water pressures. In this paper, numerous tunnel models subjected to water pressures with different action conditions were established based on FLAC3D software. The influences of the magnitude, range, and action location of local water pressures on the internal force and deformation properties, and stability of tunnel lining structure were obtained by analyzing the bending moment and axial force, horizontal and vertical displacements, and safety factor. The results show that the bending moment and axial force, and displacement of tunnel lining structure are overall symmetrically distributed when water pressures act on tunnel vault. The maximum internal force and displacement basically occur on tunnel vault and increase significantly with the increase of water pressure and its action range; while the internal force and displacement values in other locations increase slightly with different amplitudes. The tunnel vault is the most unfavorable location of lining structure. When water pressures act on left arch waist, left wall, and left arch foot, the internal forces and displacements are generally in a biased state, with a distribution pattern of larger on left side and smaller on right side. The responses of internal force and displacement at action locations of water pressure are the most rapid and maximum, and the influence degree of water pressure gradually decreases with increasing distance. Overall, the farther away from the action locations of water pressure, the greater the safety factor of tunnel structure.