加筋锈蚀对氯离子侵蚀海底隧道锚固支护结构影响分析

Influence Analysis on Sub-sea Tunnel's Anchorage Support Structure Under Chloride Environment Caused by Reinforcement Corrosion

由于长期氯离子侵蚀及干湿交替环境作用,海底隧道锚固支护结构易于加筋锈蚀,造成支护结构强度的降低.结合某海底隧道Ⅲ级和Ⅳ级围岩锚固支护结构设计,基于前人研究理论及试验成果,采用数值分析软件FLAC3D及有限元强度折减思想,探讨加筋锈蚀对锚固支护结构体系承载作用的劣化影响.研究表明,(1)锚杆锈蚀削弱了锚固支护结构的支护强度;随着加筋锈蚀的增加,隧道加锚围岩的变形逐渐增大;锈蚀对隧道加锚围岩起拱线处的收敛变形影响最明显,Ⅲ级围岩位移锈蚀影响度最大可达56.7%,Ⅳ级围岩位移锈蚀影响度最大可达62.98%.(2)锚杆锈蚀降低了锚固支护结构的锚固作用,锈蚀对锚固注浆体的黏结作用的损失影响比对锚杆应力作用的损失影响大;Ⅲ级围岩锚杆最大应力锈蚀影响度最大为11.6%,锚固注浆体最大剪应力锈蚀影响度最大达18.6%;Ⅳ级围岩锚杆最大应力锈蚀影响度最大为12.3%,锚固注浆体最大剪应力锈蚀影响度最大达20.1%;说明锈蚀对Ⅳ级围岩锚固支护结构影响比Ⅲ级围岩略大.研究结果可为海底隧道锚固支护结构运营风险评估提供一定的数据依据.

Due to the long-term chloride penetration and alternating wet and dry environmental effect,tunnel anchorage support structure is easy to rust and its strength is reduced. According to anchor retaining structure design of surrounding rock with grade Ⅲ＆Ⅳ and previous research theory and test results,deterioration of anchorage support structure system is investigated due to corrosion by means of FLAC3 D and finite element strength reduction ideas. The results are as follows：（ 1） Rust weakened the strength of anchor retaining structure; with the increase of reinforcement corrosion,deformation of surrounding rock anchored increases. the convergence deformation at springing line of tunnel＇s surrounding rock anchored is the most obvious because of corrosion,and the maximum displacement influence degree of corrosion of surrounding rock with grade Ⅲ can reach 56. 7% and that of surrounding rock with grade Ⅳ can reach 62. 98%.（ 2） Anchorage effect of anchorage support structure is reduced due to corrosion. The loss effect of bond force of anchorage body is great than that of anchor bar stress; For rock with grade Ⅲ,the maximum stress influence degree of anchor can reach 11. 6% and the maximum shear stress influence degree of anchorage body can reach 18. 6%; For rock with grade Ⅳ,the maximum stress influence degree of anchor can reach 12. 3% and the maximum shear stress influence degree of anchorage body can reach 20. 1%; These results show that deterioration effect of anchorage support structure of rock with grade Ⅳ caused by corrosion is a little bigger than that of rock with grade Ⅲ. The research results can provide some data basis for operation risk evaluation of sub-sea tunnel＇s anchorage support structure.