Study On Earthquake Damage Mechanism Of Underground Structures

Along with the rapid increase of world population and also the number of vehicles, problems like traffic jam confront countries all over the world. So, to ease the traffic congestion and develop public transportation is the urgent work for countries all over the world. Massive construction of subway around the world is a try to achieve these. Consequently, massive scale of subway construction would make the seismic resistant ability of subway a leading topic of urban engineering seismic resistance and disaster prevention and mitigation research. Underground structures'seismic damage would be hard to repair and extremely costly. It would cause some impact on the structures around such underground structures, and in more severe cases, it would endanger the urban lifeline systems. What's more, many areas in our country have high occurrence of earthquake. It is necessary to research the underground structures'earthquake response and mechanism of damage, in order to direct seismic resistant design and evaluation of seismic resistant capacity for underground structures. Having summarized relevant underground structures'seismic resistant researches, this study then focuses on work as following to explore the mechanism of underground structures'seismic damage:1. To research earthquake response and mechanism of damage for underground structures with different types of cross-section, a series of shaking table test for designed underground structures of two-floor and three-span, three-floor and three-span were implemented. And in order to simulate motion of the semi-infinite soil, multifunctional laminar shear model box was designed and manufactured. In the experiment of three-floor and three-span underground structures in clay and sand layer, what have been proved is: this shear model box solved quite well the problem with boundary effect of model box to satisfy the requirement of reducing boundary effect of model box for experiment. This proved effective model box can provide soil box with high-performance for shaking table test of underground structures with different types of cross-section in the later research.2. Having introduced several key problems involving with establishing model of simulation for underground structures in this study. And this study modeled property of the semi-infinite medium with limited soil in software ABAQUS, explored the method of using viscous boundary in ABAQUS, and proved it with justification by wave source problem and scattering problem.3. Having comprehensively introduced shaking table test of subway station of two-floor and three-span in clay. And through the analysis of acceleration history, acceleration fourier amplitude spectrum, structural dynamic response, strain and damage of subway station with two-floor and three-span, earthquake response rules and reason of damage for such a subway station were summarized.4. Having comprehensively introduced shaking table test of subway station of three-floor and three-span in clay. And through the analysis of acceleration history, acceleration fourier amplitude spectrum, structural dynamic response, strain and damage of subway station with three-floor and three-span, damage mechanism of such a subway station was summarized.5. Having comprehensively introduced shaking table test of subway station of three-floor and three-span in sand. By analyzing the acceleration, acceleration fourier amplitude spectrum, pore water pressure, structural dynamic response and structural strain, scene of ground surface after earthquake, earthquake response rule of subway station with three-floor and three-span in sand was summarized.6. Having simulated shaking table test of subway station of three-floor and three-span, and justified the results of simulation with experiment of such a subway station.7. Having simulated and analyzed an original subway station of three-floor and three-span, and illustrated damage mechanism of underground structures. Method of underground structure design are provided after that.