Study On Seismic Dynamic Response Of Tunnel In The Fault-Rupture Zone

It is inevitable to be encountered with tunnels constructed across (or close to ) faults in the design of tunnels. How to reduce the fault effect to t stability and security of tunnel structures is of importance in the design and construction of tunnels.With the extensive construction projects of highway engineering on high-intensity earthquake zone in the western area of China, the problem of tunnels across fault has ever become a key technical issue and it is meaningful to study dynamic response of tunnels across fault broken zone for the design and construction of tunnels. In this paper, the response history analysis (RHA) method is applied and the dynamic response of the tunnel across fault broken zone is system analyzed. The main contents of the paper are as follows:1) The numerical issues of dynamic history such as boundary conditions, damping model, the calculation of regional, discrete units are discussed, and the the baseline drift problem of seismic waves that exist in the random signal are solved by the use of least-squares fitting algorithm.2) The force characteristics of the horizontal section of the tunnel across fault broken zone are studied. The effects of different rock parameters, such as angle as well as the width of fault broken zones, comparative analysis of the impact factors on the dynamic response of the tunnel is performed.3) The general rules of vertical response of tunnels across fault broken zone are studied. The Comparative analysis are performed based on the dip and width of fault, internal forces, the displacement response of the tunnel lining as well as the plastic area of surrounding rock.4) The effect of deformation joint on longitudinal dynamic response of tunnels is analyzed. The results show that the joint can obviously decrease deformation, internal force and energy of lining and surrounding rock, in particular, to be effective in reducing the tunnel axial force, and thus can be used a measure for tunnels across fault broken zones.5)In the collection and analysis of statistical information about earthquake damage including the damage data on mountain tunnels across fault broken zones in the 5.12 Wenchuan earthquake, the types and characteristics of damage to tunnels are analyzed and it is concluded that the crow of tunnels is a weak point in the design of tunnels and the fortification should contain the faulted zones.