The Section Form Research Of Loess Tunnel Under Coupling Action Of Earthquake,Seepage And Train

Loess tunnel is an important part of China’s western area infrastructure. Western loess area is in high intensity area and the undesirable properties of loess bring the construction and normal operation of loess tunnel difficulty. Therefore, carrying out a comprehensive and systemic of dynamic response research of loess tunnel structure is of great significance.Currently, studies on the dynamic response of loess tunnels with different kinds of sections are mainly focused on earthquake, however, studies on the dynamic response to loess tunnels with different section forms under the action of multi-fields interactions are less. In this paper, four kinds of loess tunnel are studied as the research objects, with the aid of the finite element software ADINA,models of dynamic response to four kinds of loess tunnel structures in the form of circular, curved wall, rectangle and straight wall under the action of three kinds of multi field coupling factors are built.The major job can be listed as followed.(1) For the coupling effect of earthquake and seepage, El-Centro seismic wave is used into this model, and whose seepage flow is 100 mm rainfall, then dynamic response to loess tunnel in the form of four cross sections are analyzed. The results show that coupling effect on dynamic response to loess tunnels with different cross sections is of difference, the influence of cross section form on the acceleration, displacement and pore water pressure of tunnel structure is small, but the stress influence is great, stress distribution of circular and curved wall are uniform and the numerical value is small, the stress concentration of the arch of the rectangle and the straight wall is concentrated, and the numerical value is larger.(2) For the coupling effect of earthquake and train, the theory of vehicle track coupling is used, the coupling effect between train excitation load and earthquake in the same time is realized, then dynamic response to loess tunnel in the form of four cross sections are analyzed. The results show that under the coupling effect of earthquake and train the trend of acceleration time history curves and the displacement time history curves of the fou r cross sections are basically same under coupling action. The acceleration and displacement of each section of the tunnel is not obvious, the stress differ with each other otherwise, the stress response to the circular section is the smallest, and the rectangle is the biggest.(3) For the coupling effect of earthquake,seepage and train load, A structural model for the joint action of earthquake and train loads is established, which is coupled with fluid model of rain water afterwards. Dynamic response to four kinds of loess tunnel structures are analyzed. The results show that under the coupling effect of earthquake,seepage and train load the acceleration and displacement response to the loess tunnel with four cross sections are similar to the coupling action of earthquake and train load, however, it is different from the coupling action of earthquake and seepage. There make difference between the stress response of the three kinds of coupling, The stress response to earthquake- seepage- train load coupling is maximum,which is followed by coupling effect of earthquake and train load, earthquake seepage coupling is the least.