| With the rapid development of tourist traffic undertakings in China’s western,the advantages of tunnel have become increasingly prominent.Due to the high dangerous of the western mountains,and complex road conditions,the traffic accidents occurred frequently.In order to pass the mountains which are dangerous and difficult,the construction of the tunnel project is increasing.It is particularly important to prevent the construction accident emergency and to ensure the safety of construction operations.The study of surrounding rock deformation and stability in complex tunnel is still important research subject at present,because of the various factors affecting the deformation of surrounding rock.The deformation,forecast and stability were analyzed and studied by the theories such as artificial neural network,genetic algorithm and numerical analysis under the background of Xueshanliang tunnel in Chuanhuang road.The research content and the main conclusions are as follows:Combined with specific engineering situation of Xueshanliang tunnel,the various specific factors and their interaction were analyzed in detail,which are the influence of Xueshanliang tunnel surrounding rock deformation.Research result shows that Xueshanliang tunnel’s stability is affected prominently by mechanical properties,structure characteristic and integrity of rock mass,.high ground stress,and groundwater.The mode was used to train and predict the deformation of surrounding rock with the same geological conditions by genetic algorithm optimized BP neural network.And the prediction results were compared and analyzed with that of the traditional BP neural network.The analysis result indicates that genetic algorithm optimized BP neural network is of higher precision and practical value,when it is used to analysis the monitoring data.It can reflect accurately the nonlinear evolution discipline of surrounding rock,and reveal timely stable tendency of surrounding rock and support structure.This more efficient and predominant method is provided to optimization design and the feedback of monitoring in underground engineering.The dynamic construction process of Xueshanliang tunnel was simulated by numerical software.It is concluded that the change rule between surrounding rock deformation and each excavation step in the process of construction by analyzing the deformation characteristics of different grade surrounding rock under the condition of different excavation methods and supporting.The study found that the horizontal displacement of arch shoulder,side wall and arch foot had different degrees springback in the process of deformation;digging the downsteps has few effect on the stress redistribution and subsidence of vault;the displacements of class Ⅴ of surrounding rock at the tunnel entrance and class Ⅳ,Ⅲ of surrounding rock in the mid of the tunnel longitudinal were affected most seriously by excavation of surrounding rock in the 12 m,18m and 12 m range respectively;secondary disturbance can be avoided by full-face method in excavation of class Ⅴ of surrounding rock.It is beneficial to surrounding rock stable that rapid coherent stress redistribution and deformation.In this paper,the research results with application and reference value benefits the deformation prediction of surrounding rock and stability analysis of the similar tunnel excavation. |
