Study On The Simplified Analysis Methods Of Seismic Effects Of Underground Structures

With the rapid development of the construction of underground structures, the underground structural engineers faced numerous static design and seismic design problems at the same time. Currently, the existing studies are mostly concentrated on the using of the general commercial software for the underground structure dynamic time history analysis and the large-scale shaking table test or the centrifuge shaking table test, but their research production is difficult to apply to the actual seismic design of the underground structure. Meanwhile, the seismic design code in China is still in the research and development stage. Thus, it is very necessary to establish a system of simplified seismic design method that can be directly used for the seismic design of the underground structures. The topic research content includes: Firstly, from the underground structure quasi static solution aspects, the relationship between the free-field deformation and underground structures deformation was analysed. Then, using the numerical simulation methods, the dynamic response characteristics of free field and underground structures have been systematic studied, and the basic thinking of the underground structure simplified design methods was put forward. Based on the substructure method, the theoretical derivation and improvement of the response displacement method and the static finite element method(SFEM) were respectively conducted. Finally, this paper introduced the elastic-plastic analysis methods and the pseudo static test numerical simulation of the underground structures. In this paper, the main research work and research results are as follows:1. Study on the pseudo-static deformation relationship between the free field and underground structures based on the analytical solutions.Based on the theory of plane elastic complex variable function, the circular and rectangle underground structures were analysed. Meanwhile, the methods of the Wang, Penzien, Bobet, Park and Huo were analyzed through the two parameters(the relative stiffness of the soil and structure, the deformation coefficient).2. Study on the relationship between the free field and the soil-underground structure scattering fieldBy means of the numerical simulations, the dynamic response of the free field and the soil-underground structure scattering field are studied under the action of P wave and S wave. Comparative analysis of the dynamic characteristics(acceleration, stress and so on) of the max and the time when the relative displacement dynamic response of the soil and the structures. Through these dynamic characteristic analysis, we can find out the dynamic characteristics and the contact between the free field and the soil-underground structure scattering field.3. The theoretical derivation and improvement of the response displacement methodBased on the principles of the substructure method, the response displacement method was derived to solve the seismic response of underground structures. And on the basis of the theoretical derivation, proposed a variety of the spring coefficient solution methods and the seismic load(shear stress, the soil displacement differential equivalent load and inertia force) solving method was improved. the accuracy of the improved response displacement method was verified through the Specification response displacement method and the overall dynamic time history analysis method.4. The theoretical derivation and improvement of the static finite element method(SFEM)Based on the principles of the substructure method, the static finite element method(SFEM) was derived and the existing static finite element method(the Forced boundary displacement method, the reaction acceleration method, the reaction stress method) were introduced. Based on the theoretical analysis, a new static finite element model was proposed, and its computational accuracy was verified.5. The elastic-plastic simplified analysis method of the underground structureUsing foundation stiffness attenuation method, the specification response displacement method and the improved response displacement method were comparative analysed under different ground motion. Meanwhile, the static finite element method(SFEM) and the dynamic time-history method in elastoplastic soil conditions were compared. Finally, using the numerical simulation method, the pseudo static elastic-plastic response of the underground structures was simulated.