Dynamic risk obtaining method for tunnel large deformation disasters

The invention belongs to the technical field of tunnel engineering, and discloses a dynamic risk acquisition method for tunnel large deformation disasters, which comprises the following steps: S1, identifying risk disaster-causing factors according to historical data of the tunnel large deformation disasters; S2, selecting a prediction index according to the risk disaster-causing factor, and establishing a probability prediction model according to the prediction index; S3, dynamically updating surrounding rock parameters by using a Bayesian method and a Markov random process method according to the prediction index and the exposed surrounding rock information of tunnel face excavation; S4, according to the surrounding rock parameters, the prediction indexes and the probability prediction model, carrying out posterior risk updating and acquiring a dynamic risk prediction result of the tunnel large deformation disaster. The method solves the problems that in the prior art, a set of quantitative risk evaluation model capable of reflecting a large deformation action mechanism cannot be established, effective feedback of surrounding rock and support information in the construction period cannot be effectively utilized, and a dynamic and informationized risk evaluation theory cannot be formed.