| With plenty of constructions of large scaled underground powerhouse group,earthquake damage cases appear constantly. The engineering safety is being paidmore and more attention to. Especially in recent years, such constructions in Chinaare springing up with complicated structures and unprecedented construction scale, sothe earthquake security is becoming a big challenge Seismic action is the mainexternal factor threatening the long-term operation safety of these constuctions. Oncethe earthquake happens, the underground engineering could be damaged. Then thesecondary disaster follows. Therefore researches on the behavior of suchconstructions under seismic action are very important.On the basis above, this article is aiming at the key scientific problem of disasteranalysis of these structures under seismic action, using the advanced theory andtechnology of interdiscipline to carry out catastrophe simulation, such as3Dgeological modeling and numerical methods. The main work and research results ofthis article are shown below:1. Based on the3D geological model, the modeling theory and analysis methodfor catastrophe simulation of underground powerhouse group under seismic action ispresented. Some complex geological factors are considered comprehensively, such asspace surface faults, fluctuation formations, joint fissures and local block surroundedby those surfaces. A3D refined geological model is built up. The stochasticprobability model is applied to analyze the generation probability of surface blockwith different fault joint combination. Based on the above, the finite element modelfor catastrophe simulation is established coupling with geological model, undergroundpowerhouse structure and seismic loads. The establishment of the model provides atheoretical basis for revealing the inherent law of the earthquake catastrophe.2. The selection and adjusting principle of seismic wave is researched. Based onthe transient earthquake response analysis theory of stratification geotechnical mass inthe frequency domain by Liao Zhen-peng, the seismic record is reversed from theground to the bedrock using MATLAB. The mean square acceleration method is used for baseline correction of the seismic wave. The Butterworth filter is applied toeliminate the high frequency component. The method above effectively improves thevalidity and rationality of the numerical simulation. The finite element model isestablished coupling with the infinite element as static and dynamic boundary in theseismic analysis. In addition, the selection of dynamic damping and element size arediscussed in this article.3. This article puts forward a method combining whole and partial model indynamic simulation of underground powerhouse group. With the finite element modelcombining global cavern analysis with local curved block analysis, a numericalmethod for simulating seismic response and catastrophe is built up. Considering thefailure process of the joint fissures between the surrounding rock and block frombonding state to slipping state, this article develops a new nonlinear dynamic contactconstitutive model which could reflect the bonded effect of block joint planes andsimulates the failure process of local curved block under the seismic action.4. Based on actual construction in the water resources and hydropower field, thisarticle puts forward a seismic analysis and evaluation method. The improvedNewmark method-Hilber-Hughes-Tayor method is used to analyze the seismicresponse of underground global cavern and local curved blocks. Through the analysisof acceleration and stress-time history curves of global cavern and curved blocks, thecaverns’cataclysm development situation is studied.At the same time, this article hascertain guiding significance in reflecting the development process and instabilitymechanism of plastic zone of curved block near underground cravens. |
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