Research On The Stress Characteristics And Reinforcement Measures Of The Expanded Loess Tunnel

The area of loess in China is more widely distributed,the disease of the loess tunnel is prominent,and the loess is weakened by the surrounding rock in the case of watering,which affects the stability of the tunnel.With the weakening in the loess tunnel surrounding rock,the deformation of the tunnel will appear too make the original design can't meet the requirements,but at the beginning of the structure of the main reinforcement is the main factor of the tunnel.Combined with the project of Yangshan tunnel,analysis the loess tunnel under normal stress state and weakening of surrounding rock of tunnel surrounding rock mechanical behavior analysis,proposed increasing at the beginning of the structure of the main reinforcement method to strengthen the supporting structure.Using FLAC3 D finite element software to analyze the different main rebar diameter replace the design of the main reinforcement diameter at the beginning of the overall displacement of surrounding rock,structural deformation,in addition to the stress and the distribution characteristics of surrounding rock mass structure,than to select the main bar diameter is suitable for the operating conditions,provides reference for the study of the mechanics behavior of loess tunnel,the main contents include:(1)The deformation law of Yangshan loess tunnel was analyzed by monitoring data from the field.(2)Using FLAC3 D finite element software simulation analyzed the Yangshan tunnel's different loading characteristics and overall displacement when the stress is normal and when surrounding rock's is weakened after loess encountered water.Moreover,analyzing the consolidated effects of initial branch main rods loess tunnel in expansion and reinforcement at the beginning of the film takes main ?22 at the time of the reinforcement effect was analyzed.(3)FLAC3D finite element software analysis was utilized to analyze the reinforcement effect of surrounding rock when Yangshan loess tunnel is in weakening condition.To study of replacement ?22 main reinforcement by ?25 ?28,?32,?36 main reinforcement respectively.Their mechanical behavior of surrounding rock are discussed after replancement.By our study,the optimal replacement main reinforcement diameter has been found.