| The damage to the tunnel structure caused by the earthquake will not only bring huge economic losses,but also bring huge safety risks to construction maintenance and subsequent operations.Structural damage identification technology can be used for non-destructive detection in tunnels.Identifying tunnels with damage can avoid the risks caused by hidden safety hazards.Therefore,it is very important to study the evolution law of tunnel lining damage under the action of earthquake,and to locate and evaluate the lining damage.In view of this,this paper takes Biyun Tunnel as the engineering support,and establishes the damage model of tunnel lining to study the damage evolution law of tunnel lining under different seismic intensity,surrounding rock grade,lining thickness and seismic wave type,and uses wavelet packet analysis theory to achieve Damage identification of tunnel lining.The research results have certain theoretical value and practical engineering significance.The main research contents and results are as follows:1.Analyze the response of acceleration and displacement of lining under various working conditions.The results show that the peak acceleration response has a certain lag compared with the original seismic wave,the tunnel has a certain amplification effect on the seismic wave,and the increase of the surrounding rock grade will weaken the lag of the seismic wave.The acceleration and displacement response of the lining structure are gradually reduced from the vault to the invert.2.Analyze the damage evolution law of the tunnel lining under various working conditions,and combine the safety factor and the damage parameters to determine the current state of the lining structure,and make corresponding warnings to the lining structure.The results show that the lining arch foot,arch shoulder and arch waist have damage successively,and the damage gradually expands to the surrounding,showing a trend of circumferential development.The compression damage of the tunnel lining is much smaller than the tensile damage.Increasing the surrounding rock grade and lining thickness will delay the occurrence of damage,slow the development speed and reduce the damage area.The nonlinear seismic damage response of tunnels has waveform sensitivity,and there are differences in the damage degree and the time of damage of tunnel lining under different seismic waves.The arch shoulder and arch foot are the weak position of the lining.Under the action of higher intensity seismic waves,the damage of the arch waist is more serious,and damage will also occur at the invert arch.It is recommended to focus on these weak locations in seismic design.3.Based on the theory of wavelet packet analysis,Matlab is used to decompose the acceleration response of the tunnel lining in both damaged and undamaged states using wavelet packet decomposition,and the damage index constructed by the wavelet packet band energy spectrum is used to identify the lining damage.The results show that the damage index can be used to identify the location of the lining damage,and the damage degree can be roughly judged according to the sudden change of the damage index value.The damage recognition result is less affected by the wavelet packet basis function,but as the number of decomposition layers increases,the damage recognition result becomes more obvious.The damage index identification results are compared with the damage distribution of the tunnel lining in the numerical simulation.The feasibility of wavelet packet analysis for detecting tunnel damage is verified,and the location and severity of the damage can be identified. |
