摘要
近年来公路隧道火灾发生频次逐年升高,由隧道失火诱发的非衬砌段隧道围岩稳定性及其安全问题需要重视。为研究开挖卸荷叠加火灾高温效应对隧道围岩物理力学特性的影响,开展了以卸荷损伤试样为对象的高温及三轴再加载试验,对比了高温后卸荷试样质量、波速及表观特征的差异性,分析了试样力学特性及其破坏特征随温度的变化规律。结论如下:(1)高温作用后卸荷损伤试样力学特性劣化明显,温度荷载越大,试样峰值强度降低越多;(2)三轴再加载过程中,峰后应变与卸荷围压和温度关系密切,温度越高,峰后加速应变越大;(3)卸荷效应为高温改变试样的物理力学特征提供了作用通道,不同高温后卸荷岩样颜色差别较大,600℃后波速降低显著,平均降低64.73%;(4)温度荷载加剧了卸荷损伤试样的裂隙演化、扩容及结构松弛,卸荷量级与温度改变了试样主破裂面的展布形式,低温条件下围压对试样变形破坏起主控作用,高温条件下温度荷载为主控因素。研究结果可为非衬砌段隧道围岩的工程设计提供理论参考。
Recently,the frequency of highway tunnel fire has been increasing annually,which necessitates attention toward the stability and safety of surrounding rocks in the unlined tunnels exposed to fires.To investigate the influence of the high temperature and excavation unloading on the physical and mechanical properties of unlined tunnel surrounding rock,high temperature and triaxial reloading tests were carried out on unloading-damaged specimens.The differences in their mass,wave velocity,and apparent characteristics under the influence of high temperatures were compared.The variation of mechanical properties and failure characteristics of unloading-damaged specimens with temperature was analyzed.The results are as follows:(1)The mechanical properties of the unloading-damaged specimens deteriorated obviously under high temperatures,and the greater the temperature,the higher is the reduction in the sample peak strength.(2)During triaxial reloading,the post-peak strain is closely related to the unloading confining pressure and temperature.The higher the temperature,the greater the post-peak accelerated strain.(3)The unloading effect provides a channel for the high temperature to change the physical and mechanical characteristics of the samples.The color of unloadingdamaged specimens varied greatly after different temperatures.,the wave velocity decreased significantly after 600℃,with an average decrease of 64.73%.(4)The thermal load intensifies the crack evolution,expansion,and structural relaxation of the unloading-damaged specimens,and the unloading magnitude and temperature change the distribution of the dominant fracture surface of the specimens.The confining pressure plays a dominant role in the deformation and failure of the specimens at low temperatures,while thermal load dominates at high temperatures.The research results can provide a theoretical reference for the engineering design of unlined tunnels with surrounding rocks.
作者
陈兴周
陈莉丽
马彬
张旭
杜威
Chen Xingzhou;Chen Lili;Ma Bing;Zhang Xu;Du Wei(School of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi'an 710054,China)
出处
《地下空间与工程学报》
CSCD
北大核心
2021年第6期1864-1874,共11页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金(U1965107,51979218)
陕西省自然科学基金(2018JM5118)
三峡库区地质灾害教育部重点实验室(三峡大学)开放基金(2017KDZ01)
中国博士后基金(2017M613167)。
关键词
公路隧道
非衬砌段围岩
开挖卸荷
高温作用
试验研究
highway tunnel
surrounding rock of non-lined section
excavation unloading
high temperature effect
experimental study
