盾构隧道衬砌结构偏心破坏转化临界锈蚀率预测  

Prediction of critical corrosion rate of reinforcement for eccentric failure transformation of shield tunnel lining structure

作　　者：张志强[1,2] 张康健 刘新华[1,2] 刘征 封坤 唐旭[1,2] Zhang Zhiqiang;Zhang Kangjian;Liu Xinhua;Liu Zheng;Feng Kun;Tang Xu(Key Laboratory of Transportation Tunnel Engineering of the Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学交通隧道工程教育部重点实验室,四川成都610031 [2]西南交通大学土木工程学院,四川成都610031

出　　处：《土木工程学报》2024年第1期111-121,共11页China Civil Engineering Journal

基　　金：高铁联合基金(U1934213);国家自然科学基金(51878572)。

摘　　要：盾构隧道管片中的钢筋锈蚀会对结构的承载性能和破坏形态产生重要影响。一般盾构隧道结构多呈现小偏心受压状态,当钢筋锈蚀发展到一定程度时会出现小偏心向大偏心受力状态的转变,导致结构承载力下降、危及隧道运营安全。基于盾构隧道衬砌结构压弯受荷特点,设计小偏心加载的锈蚀试验柱,等效地模拟隧道衬砌的实际受力状态,分析不同锈蚀程度下试验柱跨中应变、极限承载力及裂缝的全过程演变。随锈蚀程度加重,试验柱承载力、混凝土应变、受压区高度下降速度逐渐加快,最大锈蚀率达到68.32%时,承载力最大降幅达到53.23%。试验发现高锈蚀程度(η≥46.25%)试验柱由小偏心破坏转化为大偏心破坏的现象。基于受弯构件正截面承载力理论分析,提出隧道衬砌结构由小偏心向大偏心破坏转化的临界锈蚀率理论计算方法,通过设计有限元计算流程验证了该方法的正确性。研究结果可为盾构隧道衬砌结构耐久性设计和安全评价提供理论支撑。The reinforcement corrosion in shield tunnel segments has an important impact on the bearing capacity and failure mode of the structure.Generally,the shield tunnel structure is in the state of small eccentric compression.When the reinforcement corrosion develops to a certain extent,the load state of the structure may transition from a small ec-centric load state to a large eccentric load state,leading to the decline of structural bearing capacity and the safety of tunnel operation.Based on the compressive bending load charac-teristics of the shield lining structure,corrosion test columns with small eccentric loading were designed to simulate the actual stress state of the tunnel lining equivalently.Mean-while,the entire evolution processes of the mid-span strain,ultimate bearing capacity,and cracks of test columns under different corrosion degrees were analyzed.With the increase of corrosion,the bearing capacity,concrete strain,and the depth of the compression zone of test columns decrease more and more rapidly,when the maximum corrosion rate reaches 68.32%,the maximum reduction of bearing capacity shall be 53.23%.It is found from the tests that the damage states of test columns with high corrosion degree(n>46.25%)may transform from small eccentric damage to large eccentric damage.Based on the theoretical analysis of the normal section bearing capacity of flexural members of reinforced concrete,the theoretical calculation method of critical corrosion rate for the transformation of the tunnel lining structure from a small eccentric state to a large eccentric failure was proposed.Furthermore,the correctness of the theoretical calculation method was verified by designing the flowchart of finite element computation.The research results may provide theoretical support for durability design and safety evaluation of the shield tunnel lining structure.

关 键 词：盾构隧道 钢筋锈蚀 破坏形态转变 临界锈蚀率 偏心受压构件 

分 类 号：U455.43[建筑科学—桥梁与隧道工程] U451.4[交通运输工程—道路与铁道工程]