Abstract: To reveal the deformation and failure mechanism of anchored surrounding rock in tunnels in rich water stratum under blasting impact load, a mechanical model of anchored surrounding rock under static load considering pore water pressure had been established, and the radial and tangential stresses under static loading had been derived. Based on the principle of coordinated deformation between bolts and surrounding rock, an analytical expression for the deformation range of water-rich tunnel surrounding rock considering blasting disturbance had further been derived. The stress, plastic zone, and displacement distribution of anchored surrounding rock under two different working conditions had been simulated and analyzed. The results had shown that blasting impact load and pore water pressure had caused damage weakening to the mechanical strength of anchored surrounding rock, reducing the strength and stability of the rock mass and enlarging the range of plastic deformation and failure. The radii of the plastic zone and fractured zone of anchored surrounding rock had been found to be closely related to blasting impact load, damage degree, pore water pressure, and blast hole layout parameters. Compared with static loading conditions, under combined static and dynamic loading, the minimum principal stress of anchored surrounding rock had increased by 39.26%, the maximum principal stress by 52.61%, and the vertical displacement by 8.03%, while the plastic zone range had further expanded. Furthermore, based on theoretical calculations under blasting impact load considering pore water pressure, the plastic zone and fractured zone thicknesses of anchored surrounding rock in the K196.8–K319.7 section of the Shenwa Railway Tunnel were calculated to be 1.98 m and 1.25 m, respectively. Field borehole inspection had verified the rationality of the theoretical analysis.