| In tunnel engineering, lining and surrounding rock are interactive whole. However, there is a common phenomenon that quite a proportion of linings exist cavity behind them. The cavity poses threats to the stability of tunnel under earthquake. Because of the difficulties in discovering, analyzing and disposing of cavity, it carries both academic value and practical significance to study the dynamic stability of tunnel with cavity behind lining.The research methods of this thesis combine with theoretical analysis, numerical simulation and project example analysis. The dynamic response of tunnel with cavity and the influence of cavity’s location, size and so on on lining and surrounding rock were studied. The failure mechanism of tunnel in earthquake was also researched, and a simplified calculation method of underground engineering seismic response was put forward. The main conclusions in this thesis are as followings.(1) The cavity causes the lining deforms to the surrounding rock outwards. The safety factors of lining decline and the area of rock’s plastic zone increases. The greater size and initial stress are, these tendencies are more obvious.(2) The shear seismic response is maximum and the vertical seismic is minimum under earthquake in different direction. Underground structure such as tunnel has little effect on the stratum response. The differential deformation in surrounding rock results in an additional internal force to the structure.(3) The stress of the lining nearby the cavity increases under earthquake and can cause the structure damage when it exceeds the strength of materials. Also the pressure of surrounding rock will grow as the accumulation of rock’s plastic strain. It indicates that the tunnel will be severely damaged when earthquake intensity greater than eight.(4) The cavity located on haunch is more effective than arch. The effect of cavity is more heavily when initial stress is greater, The influence of cavity’s longitudinal length and angle in circumferential direction is obviously greater than depth. The end effect is quite obvious in longitudinal direction.(5) The simplified calculation method is convenient and feasible, the exist of cavity will enlarge the damage of tunnel under earthquake. It shows that when the angle more than 30° and the length of axial direction equal or more than ring’s length, the tunnel will suffer more destruction.This thesis contains 132 figures, 35 tables and 118 references. |
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