含水量对隧道衬砌混凝土耐火性能影响试验研究

Experimental research on influence for water content to the fire-resistant property of tunnel lining concrete

火灾对特长公路隧道衬砌混凝土产生不同程度的损伤,含水量对隧道衬砌混凝土的耐火性能影响较大。对3种不同含水量的混凝土标准试块分别在不同的温度条件下(200,400,600,800,1 000℃)恒温加热5 h后静置冷却,测量其残余抗压强度和劈裂抗拉强度,并与常温下试块的强度进行比较。研究结果表明:高温下混凝土试块爆裂的频率和损伤程度随含水量的升高而加大,混凝土中水分加剧了混凝土耐火性能的劣化;C25混凝土发生爆裂的温度范围为500～600℃,爆裂的临界含水量为6%～8%。此结果可为火灾后隧道衬砌结构的鉴定、修复与补救提供参考。

Fire produces different degrees of damage to extra-long highway tunnel lining concrete,and the fire resistance performance of concrete is considerably effected by water content.Three groups of concrete standard test blocks with different water contents were heated for 5 hours at constant temperature respectively subjected to different temperature conditions（200,400,600,800,1 000 ℃） and put aside after being cooled.The residual compressive strength and splitting tensile strength was measured,compared with that of the test blocks at normal temperature.The results show that the blasting frequency and damage degree of concrete test blocks at high temperature increased with the rise of water content.The deterioration of fire resistance for concrete is exacerbated by the water in the concrete.The blasting temperature range and corresponding critical water content of C25 concrete is respectively 500～600 ℃ and 6%～8%.The research findings can provide reference for the identification,restoration and remediation of post-fire tunnel lining structure.