Study On The Dynamic Response Of The Shield Tunnel And Surrounding Peat Soil

The development of the underground traffic has brought great convenience to people's daily life,at the same time a lot of new problems such as environmental vibrations and uneven settlement of foundation have appeared which becomes the hot topic of research object.In view of this,considering the background of the long term operating performance of the Kunming peat soil which subjected to subway traffic loading,this thesis attempts to do some work actively about the vibration response of tunnel surrounding soils induced by the subway traffic loading.Theoretical analysis and numerical simulation are taken as the main technological measures to perform the investigation.The original work is presented in detail as follows.Firstly,based on the predecessors' experience and the existing theoretical results,this thesis simulated subway traffic loading with the variation of speed and carrying capacity by using artificial excitation function.The study found that: the variation of speed has a great influence on the peak value,load amplitude and the load frequency of the subway traffic loading.With the increase of subway speed,the peak value and load amplitude increase gradually,the load frequency increase obviously.The carrying capacity has nothing to do with the load amplitude and load frequency but play an important role on the peak value of the subway traffic loading.With the increase of carrying capacity,the peak value increase gradually,the load frequency and load amplitude remains as usual.After that,a three dimensional finite element model on the vibration response of tunnel surrounding soils is established,obtained subway traffic loadings are then imposed on the three-dimensional model so that the vibration response of the shield of tunnel and surrounding peat soils is performed through intersection experiment design principle.It is found that the vertical vibration acceleration of the surface soil is the largest,the portrait one is the second,the horizontal one is the smallest,and the vibration acceleration is enlarged in the distance.The vertical dynamic stress of the tunnel foundation is the largest,the portrait one is the second,the horizontal one is the smallest.The closer the soil is to the position of the load,the greater the dynamic stress value and the faster the attenuation.Finally,this thesis simulates the influence of dynamic response induced by the variation of speed and carrying capacity.It is found that the peak value of vibration increases with the increase of the speed,but the magnification of the vibration acceleration during the propagation remains as usual.The change of the subway velocity has little effect on the dynamic stress peak and the attenuation effect.With the increase of the carrying capacity of the subway,the peak value of the vibration acceleration and the dynamic stress increases.