Research On Seismic Response And Seismatic Design Of Tunnel Crossing Fault

As we all know, the physical property of the soil around the tunnel determines seismic wave’s propagation and attenuation characteristics, and tunnel structure’s has the same seismic behavior with the surrounding rock, so the seismic response of tunnel is greatly affected by the surrounding rock conditions. Practice has proved that:with good rock surrounding, the underground structure (such as tunnel, underground factories, etc.) has a good aseismic ability, which is significantly better than the ground structure’s, and tunnel’s earthquakedamage is generally occurs at the zoon with poor rock conditions or great change in geological conditions and somewhere with poor geological conditions. Fault zone is the site with poor quality rock surrounding, significant stress concentration, and its transitional segment hasa transformation from poor geological conditions to better geological conditions or from a better to the poor. Fault zone is usually accompanied with apparent creep, and other dynamic features like this, this is the zone where the tunnel damage concentrated, so research on this engineering fracture zone’s seismic responsecharacteristics has important practical significance. This dissertation relies on Sichuan Science and Technology Support Program’high intensity earthquake zone tunnel seismic damping key technologies research’ and the Ministry of Railways key technology projects’railway tunnel seismic design criteria and methodology research’ and has consulted a lot research on seismic damping technology of large tunnel through active fault, the main work and research results are as follows:1. Collating and analyzing existing damage data of the tunnel through fault fracture zoneAfter analysing the damage of the tunnel crossing fault zones happened the big earthquake domestic and foreign(like 1995 southern Hyogo earthquake,1999 Taiwan Chi-Chi earthquake and the 2008 Wenchuan earthquake), this dissertation analyzed and summarized the tunnel damage model, damage mechanisms and the corresponding damagetypes found in fault fracture zone.2. Revealing the tunnels’seismic response characteristics via shaking table model test and numeric calculationIn this study, a shaking table test is conducted which simulated the seismic response of a tunnelthrough a large fault zone, by changing the seismic parameters, etc. the ground and lining structure’s seismic response characteristics and laws has been systematically studied.3. Exploring the aseismic measures for tunnel through fault fracture zoneCombing the shaking table test result with the numerical simulation result, this paper analyzed the damping effect of different seismic measures, and obtained the optimal combination of these measures. In the case of GaoligongshanZhen’an fault, this study discussed tunnel’s seismic response considering the effect of different transverse sectionshapes, and evaluated the effect of aseismic structure measures which are achieved mainly by enlarging excavation and applying flexible hinge. Besides, this paper has also discussed the optimal length of the seismic measure applied to both sides of this fault.Viacollating and analyzing information, theoretical analysis, numerical simulation, shaking table model test, this dissertation combined the problems with the needs of railway tunnel construction in high seismic intensity zone, revealing the tunnel lining’s dynamic response characteristics and distribution at different venues and seismic conditions; these results is of great significance to the understanding of seismic response characteristics of tunnel crossing fault zone, and provide a valuable basis data for the later tunnel design and construction.