The Floor Heave Seismic Damage Of The Tunnel And Its Prevent Measures

Our country is a country that has serious earthquake disasters. From the newChina founded, several big earthquakes that happened in our country has broughtconsiderable economic losses and casualties, and the ground buildings, bridges androads has been damaged seriously, even the tunnel and underground structureconsidered suffering earthquake disasters hardly are subjected to different degreedamage, and part of them are subjected to floor heave disaster. However, there are nocomplete tunnel seismic design code in our country now, therefore, the preparationwork is imminent. Found in the tunnel seismic damage data, as the inverted arch formdifferent, the degree of tunnel floor heave disaster is different. So it is necessary tosearch for the curvature radius boundaries of tunnel inverted arch. Existing tunnelaseismic design using static analysis method, it is difficult to reflect the actualsituation of earthquake action, so the dynamic finite element method is adopted toresearch the problem of tunnel floor heave, it has certain theoretical significance andsocial significance.A lot of relevant information of floor heave problem are gathered in this paper,the status quo of researcheson on the floor heave problem at home and abroad areobtained. In this paper, it studies the seismic response of the tunnel by means of largefinite element software ANSYS numerical simulation. Firstly, determining thecalculation model and selecting appropriate material parameter, and then severalpossible influencing factors about displacement and stress of tunnel lining are studiedby using the EL Centro earthquake waves, the recommended value range of invertedarch curvature radius is gained and the floor heave disaster could be reduced. Throughanalysis, the main achievements following are obtained in this paper.Firstly, under vertical earthquake load, El Centro earthquake waves, tunnelstructure’s displacement and stress are changed with the change of tunnel invertedarch curvature radius. According to the study, the inflection point in the curve of thedisplacement, the first principal stress and the third main stress is not changed withthe model’s change, and the inflection point appears in the position of the invertedarch curvature radius at7.64m, therefore, this inflection point is viewed as theboundary of the tunnel inverted arch curvature radius.Secondly, when the surrounding rock conditions and seismic wave directionchanged, the inverted arch curvature radius boundary of the tunnel under seismic action does not change, it still keeps in the vicinity of7.64m.Thirdly, in seismic design of tunnel structure, to avoid the appearance of tunnelfloor heave, the most appropriate inverted arch curvature radius of the tunnel in soilsurrounding rock is from7m to8m, but inverted arch curvature radius of the tunnelin rocky surrounding rock should try to avoid designing within7m to8m.The forth, deformation of the tunnel lining structure increased with thedecreasing of surrounding rock level, and the maximum main stress reduced with thedecreasing of surrounding rock level. In soil surrounding rock, the tunnel structure isaffected greatest by the earthquake when the seismic load is added in the verticaldirection. In rocky surrounding rock, the tunnel structure is affected greatest by theearthquake when the seismic load is added in the horizontal and vertical direction.