Fire Damage Characteristics Of The Xinqidaoliang Tunnel Lining And The Safety Research Of The Structure

In recent years, with the development of national economy in our country, the trafficvolume is increasing, the risk of traffic accidents which happen in the tunnel thatcause fire also continues to increase. The fire accident that damage tunnel liningstructure (crack,drop out,water leakage) happens frequently, to the threat of people’slife and property.people began to focus on the characteristics of lining structure afterthe fire damage and safety evaluation, then carrys out a series of studies. This articlemainly according to actual damage situation of the Xinqidaoliang highway tunnelwhich causes by fire accident,then integrates the existing research results andcombines with model test and numerical simulation technology to study damagecharacteristics of tunnel lining structure after fire and safety evaluation.The mainresearch conetents are as follows:(1)According to the situation of fire damage in the site of tunnel,we build a tunnelmodel in the scale of1:2.7.After the fire test,we get the temperature distributionregulation of the internal tunnel lining.(2) On the basis of the temperature field of lining section, combining model testwith different vertical and horizontal parts of the field sampling in the site of tunnel,we study the fire damage characteristics in detail of the tunnel under the conditions ofdifferent temperature and moisture content.(3)By measuring the residual bearing capacity in different cross-section of liningstructure after fire test. We make a summarize of deteriorating regulation of thephysical and mechanical properties of concrete in different temperature zones anddifferent lining depth which refers to the results of site investigation. At last weanalyze the safety of the lining structure.(4)By finite element analysis software ANSYS, we evaluate nine kinds ofworking condition about the stress of the lining, the deformation and safety withdifferent lateral pressure coefficients of tunnel lining after fire. Under the different stress fields, the most significant influence of the fire damage to the fire side lining ison arch, spandrel, hance is impacted secondly, minimum influence is on arch feet.With the increase of the lateral pressure coefficient, the stress on the inverted archincreases significantly, and the degree of fire damage also increases obviously. Withineach stress field, when the tunnel vault is of less than34cm, or the thickness ofconcrete dropping is of over16cm, stress of lining increases much greater than theprevious working conditions. The stress of tunnel lining structure increases greatly,while the overall safety of lining structure reduces consequently.Test results of this paper and the related conclusions aimed at to providereference to identify the damage degree of tunnel lining structure and evaluate thesafety of tunnel lining structures after fire hazard.