The Evaluation of the Tunnel with Structural Defects in Lining and its Countermeasures


Toshihiro ASAKURA,
Dr.Eng. Chief Engineer, Tunnel Engineering Group,
Structure Technology Development Div.,
Technological Development Dept.

Yoshiyuki KOJIMA,
Senior Engineer, Tunnel Engineering Group,
Structure Technology Development Div.,
Technological Development Dept.

Yutaka SATO,
Engineer, Tunnel Engineering Group,
Structure Technology Development Div.,
Technological Development Dept.

Kazuhide YASHIRO,
Engineer, Tunnel Engineering Group,
Structure Technology Development Div.,
Technological Development Dept.

Toyohiro ANDO,
Vice-Manager, Railway Facilities Div.,
Facilities Dept, East Japan Railway Company



Most tunnels have structural defects, such as thin lining at the crown and presence of an opening behind the lining because of the construction technique applied. Model tests and frame analyses are carried out to learn the influence of defects on deforming behavior of the lining and the effect of countermeasures such as a back-fill grouting and an inner reinforcement with the following conclusions drawn: 1) The strength of the tunnel with defective lining is much smaller than that without defect. and 2) The strength of the tunnel recovers with execution of countermeasures.