The invention discloses a harmful deformation prevention and control method for a hydraulic soft
rock tunnel, and the method comprises the steps: carrying out the preliminary classification of the surrounding rock of the tunnel according to the
geological survey result of the tunnel, and dividing a
deformation control target into four grades; supporting measures which are based on harmful deformation classification and conform to the deformation characteristics of the red-
bed soft
rock tunnel are provided by considering the characteristics of water
physical property, rheological property and the like of the red-
bed soft rock; in the construction stage, a soft
rock tunnel harmful deformation
analysis method under the seepage-rheological
coupling effect is adopted for determining the reserved deformation amount, and according to an improved constraint-convergence method, the supporting opportunity is calculated and determined based on a surrounding rock characteristic curve and a
safety coefficient; and finally, according to geological conditions exposed by excavation and necessary supplementary survey results, calculating and analyzing the harmful deformation index again, and dynamically adjusting the harmful deformation grade and the support measure of the specific hole section. According to the method, through a scientific supporting mode and
dynamic management, tunnel deformation can be effectively controlled, and the adaptability and long-acting stability of red layer soft rock tunnel supporting are improved.