Research On Prototype Test Of Large Diameter Shield Ring Lining Structure Under Fire Conditions

With the popularity of shield construction method and, with the popularization and application of shield lining fire prevention has become the focus on important part of tunnel fire, with domestic and foreign subway tunnel fires occur frequently, the lining structure under different degree of damage, because the subway shield tunnel fire, high temperature can make the strength of the lining structure materials decreased significantly, which resulted in increased structural deformation, bearing capacity decline. In the present experiment, the fire research of lining structure research, especially large shield environment is particularly important。Based on the large diameter three-ring prototype lining segment level far ballast test, used in the large diameter shield is introduced of three-ring assembly test plan, by temperature load applied in the segment test, on the analysis of the structure of the segment lining deformation and the analysis of the loading force, and then to summarize segment changes of temperature and phenomenon is explained, it is concluded that the following results:(1) Segment lining system is obtained by the fire simulation experiment, distribution in high temperature under the action of temperature variation phenomenon; In the experiment 3 hours fire cases, up to about 100℃, which when the segment was broken, the highest temperature can reach 140℃ above;(2) In third fire damage law of lining structure under the condition of laboratory, segment joint with high temperature, affected by the fire duration longer, joint open, the greater the resistance to deformation and joint capability is weak. Resistance to deformation ability is abate, makes the segment under the effect of external force, the joint security increase;(3)3 piece of lining with loop system is obtained by experiment, the overall deformation. Through the deformation can be seen that the segment lining system overall deformation performance of smaller; Segment lining system damage, vault closed in tension, the lateral compression, hance instead, inner pressure, the lateral tension, from the open quantity of segment joints and ctoa is clearly visible. Measured at the same time segment open amount and ctoa, consistent with the segment ring deformation;(4) Through this level of large diameter three-ring prototype segment lining fire ballast test, under the action of high temperature, in 3 hours fire directly affected by the fire location segment has serious blowout phenomenon, not directly affected by the fire location segment local concrete cracking due to the influence of the smoke flow falls off phenomenon.By analyzing the rule of lining structure under fire, for evaluation of shield tunnel under the effect of fire provides the theory basis for safety assessment. Put forward to improve the performance of segment lining structure strength and fire protection, reasonable protection measures for the safety of the underground road operations provide strong guarantee.