特长水下公路盾构隧道结构防火保护策略及关键参数研究  

Study on structure fire protection strategy and key parameters of extra-long underwater highway shield tunnel

作　　者：谢宝超[1] 阳旖 郭晨阳 戴伟强 赵蓓 陈珊娜 Xie Baochao;Yang Yi;Guo Chenyang;Dai Weiqiang;Zhao Bei;Chen Shanna(Central South University,Changsha 410083,China)

机构地区：[1]中南大学,湖南长沙410083

出　　处：《土木工程学报》2024年第4期92-101,共10页China Civil Engineering Journal

基　　金：国家重点研发计划(2017YFB1201204)。

摘　　要：特长水下公路盾构隧道普遍设置独立排烟道进行顶部集中排烟。现有隧道工程防火技术“护顶不护墙”,顶部设有排烟道时,顶部防火保护施加在烟道板上,而烟道层拱顶管片及车道层两侧管片不施加防火保护,存在安全隐患。根据隧道结构实际可能受到的火灾高温作用,结合管片、烟道板结构相对重要性,提出了新的车道层侧墙管片、烟道层拱顶管片、烟道板结构防火保护策略,即车道层所有结构表面采用RABT火灾升温曲线,烟道层所有结构表面采用基于CFD模拟的火灾升温曲线,耐火极限均不小于2.0h,管片耐火极限由管片混凝土表面及距表面25mm处温度判定,烟道板耐火极限由烟道板的极限弯曲变形量和极限弯曲变形速率判定。基于所提出的防火保护策略,开展数值模拟及耐火试验研究,确定了防火保护技术参数。结果表明:车道层侧墙管片防火保护层等效热阻应不小于0.10℃·m~2/W;烟道层拱顶管片防火保护层等效热阻在排烟口处不小于0.10℃·m~2/W,且随距排烟口距离的增大逐渐减小,距离排烟口16m处减小为零;隧道侧墙常用装饰材料搪瓷钢板在火灾过程中易发生变形而脱落;无防火保护烟道板耐火极限大于2.0h,掺加PP纤维、钢纤维可提升烟道板的耐火性能。The extra-long underwater highway shield tunnel is generally equipped with a flue at the top for centralized smoke exhaust.The existing fire protection technology of tunnel engineering"protects the top without protecting the wall".When the top of the tunnel is equipped with flue,fire protection is applied to the flue plate,but the vault segment of the flue layer and the side wall segment of the driveway layer do not apply fire protection,which leads to safety risks.According to the effect of fire and high temperature on tunnel structure and the relative importance of segment and flue plate structure,a new fire protection strategy is proposed for the structure of the side wall segment of the driveway layer,the vault segment of the flue layer and the flue plate.RABT fire curve is adopted for all the structural surfaces of the driveway layer,and the fire temperature based on CFD simulation is adopted for all the structural surfaces of the flue layer,and the fire resistance limit of all structures is not less than 2.Oh.The fire resistance limit of the shield segment is determined by the temperature of the segment surface and 25mm away from the surface,and the fire resistance limit of the flue plate is determined by the limit bending deformation and the limit bending deformation rate of the flue plate.Based on the proposed fire protection strategy,numerical simulation and fire tests are carried out to determine the technical parameters of fire protection.The results show that the equivalent thermal resistance of the fire protection layer of the side wall of the driveway layer should not be less than 0.1℃·m^(2)/W.The equivalent thermal resistance of the fire protection layer at the smoke vent should not be less than 0.1℃·m^(2)/W,and gradually decreases with the increase of the distance from the smoke vent,and decreases to zero at 16m from the smoke vent.The enamel steel plate commonly used as the decorative material of tunnel side wall is easy to be deformed and fall off during fire.Without fire protection,the fi

关 键 词：特长隧道 盾构管片 烟道板 防火保护策略 等效热阻 

分 类 号：U452.2[建筑科学—桥梁与隧道工程]