Nondestructive Testing and Safety Assessment for Supporting Structure of Highway Tunnel
|Keywords||Highway Tunnel Ground Penetrating Radar Supporting Structure Defect Numerical Simulation Safety Assessment|
At present, highway tunnel always use the new Austrian method to construction in our country. Supporting structure may appear quality problems. For example, cavity may exist behind the primary support, shotcrete may appear less thickness, the length and number of bolt may be inadequate, secondary lining may appear less dense or lack of thickness . This paper uses 11 tunnels in Xinzhou to Baode highway as the research background. On-site testing contents, numerical simulation analysis and theoretical analysis are used when cavity exsist behind the primary support and secondary lining appear thickness quality problems. The main research contents and results are as follows:①RAMAC ground-penetrating radar system is used for the quality of the tunnel support structure. On the basis of data collecton and processing, a typical initial support defects and secondary lining defect image are shown.②This paper summarize parts of on-site testing contents of 11 Short tunnel in Xinzhou to Baode highway,such as cavity behind the primary support and thickness quality problems in secondary lining. The regular pattern of position which is easy to cause emerge in primary support and secondary lining is given at last.③Finite element software ANSYS is used to the numerical simulation analysis when cavity exsist behind the primary support, This paper investigated different positions and different size cavity impacting on the displacement of surrounding rock and support structure, distribution of plastic zone of surrounding rock and internal force of primary support.④Finite element software ANSYS is used to the numerical simulation analysis when the secondary lining is as a whole less or the vault, arch back, side wall thickness of less. The safety factor is obtained in deep tunnel at IV-class, shallow tunnel at V-class and deep tunnel at V-class. In order to ensure the safety of the tunnel, the minimum safe thickness is given in all cases.