列车动荷载作用下海域段盾构隧道衬砌结构耐久性研究

Study on structure durability of submarine shield tunnel lining under train dynamic load

为研究运营海域盾构隧道衬砌受海水侵蚀与列车动荷载双重作用下的结构耐久性问题,本文以厦门地铁6号线马銮中心站至集美岛站海域段隧道工程为基础,通过室内三轴试验确定盾构隧道管片混凝土腐蚀前后力学性能,并使用MIDAS GTS有限元软件分析盾构隧道衬砌受Cl^(-)侵蚀后承载能力变化及隧道衬砌在列车动载下的响应情况。结果表明:随着Cl^(-)的侵蚀,管片混凝土强度明显降低,平均弹性模量下降了46.13%;单次列车荷载与海水侵蚀双重作用下衬砌结构横向位移不大,纵向位移由56.9 mm增大至57.8 mm,最大拉应力增加6.42%,最大压应力增加14.16%;单次列车荷载持续作用下,管片最大可产生7.43 mm纵向位移,衬砌左右两侧产生的应力较大,最大约5.5 MPa,应力随时间均匀变化。延长海域盾构隧道运营时间衬砌结构劣化明显。

To solve the durability problem of submarine shield tunnel lining under the dual roles of seawater erosion and train dynamic load,the mechanics of shield tunnel tube sheet concrete before and after corrosion were determined by indoor triaxial test,and the changes of bearing capacity of shield tunnel lining subjected to Cl^(-)erosion and the response of tunnel lining under dynamic train load were analyzed based on the subway tunnel projects between Xiamen metro line 6 Maluan central station and Jimei island station.The results of test showed that:With the deepening of Cl^(-)erosion,the strength of shield tunnel slice concrete decreased obviously,and its mean elasticity modulus decreased by 46.13%;Under the double action of single train load and seawater erosion,the lateral displacement of the lining was small,the longitudinal displacement of the lining increased from 56.9 mm to 57.8 mm,the maximum tensile stress and the maximum compressive stress increased by 6.42%and 14.16%,respectively;Under the continuous action of single train load,the maximum longitudinal displacement of the tube segment was 7.43 mm,the stress on the left and right sides of the lining was relatively large,the biggest value was 5.5 MPa,and the stress varied uniformly with time.It could be seen that with the increase of operation time,the durability of the lining structure of ocean shield tunnel decreased,obviously.