Research On Dynamic Response Of Tunnel Under The Action Of P Wave Based On Strain Gradient Nonlocal Biot Theory

With the rapid development of urban subway,the dynamic stress response and safety safety of underground tunnels under the action of seismic waves and explosion seismic waves generated by nearby drilling and blasting method have attracted widespread attention.In this paper,the relevant research on tunnel dynamic response at home and abroad is summarized,and in view of the shortcomings of existing research,the strain gradient nonlocal Biot theory is used to consider the effects of non-uniformity of saturated soil skeleton structure and soil pore size effect on tunnel dynamic stress under the action of P wave.In this paper,the dynamic response of infinitely long tunnel lining under P wave under saturated soil medium is taken as the research object,and according to the strain gradient nonlocal Biot theory,the wave function expansion method is used to derive and calculate the wavenumber in saturated soil and the stress expression of the soil skeleton,and the following research is carried out:Aiming at the dynamic stress response problem of deeply buried single layer cylindrical tunnel lining under the action of P wave in saturated soil medium,the wave function expansion method was used to solve the problem,and the influence of incident P wave frequency,scale factor and nonlocal parameters on the dynamic response of the lining was analyzed.The results show that nonlocal parameters and scale factors have an effect on the dynamic stress of the lining,and the higher the incident P wave frequency,the greater the influence.Aiming at the dynamic stress response of deep buried double layer composite cylindrical tunnel lining under the action of P wave in saturated soil medium,the wave function expansion method is used to solve the problem,and the influence of P wave input radio frequency rate,nonlocal parameters,scale factor,lining stiffness and lining thickness on the dynamic response of lining is analyzed.The results show that the dynamic stress concentration factor of lining is affected by nonlocal parameters and scale factors,and the greater the incident P wave frequency,the greater the influence.The influence of lining stiffness and thickness on the dynamic stress of lining changes with the frequency of the incident wave.Aiming at the dynamic stress response problem of shallow buried single layer cylindrical tunnel lining under the action of P wave in saturated soil medium,the wave function expansion method was used to solve the problem,the large circular arc hypothesis was used to simulate the surface interface,the Graf coordinate transformation was used to solve the pending coefficient of the potential function,and the influence of the incidence angle of the incident P wave,frequency,nonlocal parameters,scale factor and lining buried depth on the dynamic stress of the lining was analyzed.The results show that scale factors and nonlocal parameters have an influence on the dynamic response of the lining,and the greater the frequency of the incident P wave,the greater the influence.The incidence angle of the incident P wave has a great influence on the distribution of circumferential dynamic stress of the lining,and the buried depth of the lining has a great influence on the dynamic stress of the lining.Moreover,the influence of the incidence angle and lining depth on the dynamic stress is more complex,and there is no special law.The results show that the influence of scale factors and nonlocal parameters on the dynamic stress of tunnel lining under the action of P wave cannot be ignored.