回填影响下某公路隧道明洞衬砌开裂行为研究

Research on the Cracking Behavior of Lining in an Open Section of a Highway Tunnel Considering Backfill Influence

公路隧道工程结构的安全和稳定对交通运输系统的可靠性至关重要,隧道衬砌开裂问题直接影响结构的强度和耐久性,从而产生严重安全隐患。根据福建某公路隧道明洞衬砌开裂情况现场调研结果,利用扩展有限元XFEM计算方法,明确考虑回填影响下典型断面的开裂机制,确定主要截面安全系数。对比不同加固方式的应用效果,给出优选治理建议和措施。研究结果表明:1)该隧道进口端明洞裂缝主要分为衬砌纵向裂缝及仰拱填充层裂缝2类,裂缝主要由基底不均匀沉降及邻近隧道施工扰动引起;2)裂缝病害导致典型断面各部位安全系数相较规范值总体偏小,差值最高达56.25%;3)对比锁脚钢管桩加固、仰拱隧底地基加固、钢带加固、纤维布加固处治方法后,指出仰拱隧底地基加固为优选方案,可使断面安全系数提高至5倍以上;4)该研究可为类似隧道工程开裂病害的成因分析及治理提供借鉴。

The safety and stability of highway tunnel engineering structures are crucial to the reliability of transportation systems.The cracking problem of tunnel lining directly affects the strength and durability of the structure,resulting in serious safety hazards.Based on the on-site investigation of the cracking situation of the lining of a highway tunnel in Fujian,the extended finite element XFEM calculation method was used to clarify the cracking mechanism of typical sections under the influence of backfilling,and to determine the safety factor of the main sections.Compare the application effects of different reinforcement methods and provide optimal treatment suggestions and measures.The results show that:1)The cracks of the tunnel entrance are mainly divided into two types:longitudinal cracks in the lining and cracks in the arch filling layer.The cracks are mainly caused by uneven settlement of the foundation and adjacent tunnel construction disturbances;2)The crack disease causes the overall safety factor of various parts of the typical section to be lower than the standard value,with a difference of up to 56.25%;3)After comparing the treatment methods of locking foot steel pipe pile reinforcement,inverted arch tunnel bottom foundation reinforcement,steel strip reinforcement,and fiber cloth reinforcement,it is pointed out that the inverted arch tunnel bottom foundation reinforcement is the preferred solution,which can increase the section safety factor by more than 5 times.This study can provide reference for the analysis and treatment of cracking diseases in similar tunnel engineering.