| With the development of economic construction and needs of water resource, the constructions of earth-rock-fill dam in meizoseismal area is more and more.After the "5.12" Wenchuan earthquake, the security problem of high dams in meizoseismal area has attracted much attention.Therefore, the seismic research work of earth-rock-fill dam is of urgency and importance.Based on the damage data of Zipingpu CFRD,through model test and numerical calculation,the in-depth study of the dam’s dynamic response characteristics, the seismic failure mode and seismic mitigation technique have important significance in improving our earth-rock-fill dam seismic design level and ensuring engineering seismic safety.In recent years, the IWHR have developed large-scale shaking table model test technique and carried out a plurality of earth-rock-fill dam shaking table model tests, in the same time the experimental prototypes have good representation and have accumulated rich model test data.Therefore,based on the results of large-scale shaking table tests and combined with numerical analysis, this paper has mainly studied earth-rock-fill dam’s seismic acceleration response characteristics and earthquake resistant measures, in order to further reveal earth-rock-fill dam’s earthquake acceleration reaction rules and seismic damages and verify the effectiveness of earthquake resistant measures,improving the level of seismic design of earth-rock-fill dam.The main research contents and results are as follows:(1)On the basis of summarized large-scale shaking table test technique, combined with a plurality of earth-rock-fill dam large-scale shaking table tests carried out by the IWHR, this chapter focuses on the model design of large-scale shaking table model test and the process of implementation. It mainly includes the similarity law of model test, making of section model and the overall model, the layout and laying of acceleration sensor, test plan and so on. By doing these, the key process of the model test is summarized and the experimental data are carded, which lays the foundation for the further study of the acceleration response distribution law of the earth-rock-fill dam.(2)Through the comparison of the results of the model test, this chapter mainly studied the the acceleration response characteristics of core rockfill dam. It has summarized the distribution of acceleration response of two core-wall rock-fill dam along the direction of the dam height and the direction of the upstream and downstream and compared the acceleration response with or without water.The results show that:The seismic acceleration of core-wall rock-fill dam has obvious amplification effect along the direction of the dam height, being the strongest in the dam top 1/4 area, and the "whiplash effect" is quite obvious; The amplification effect of the slope of the core-wall rock-fill dam is obvious, and the acceleration response of the downstream dam slope is greater than that of the central line and the upstream dam slope; The acceleration magnification of the core-wall rock-fill dam decreases with the increase of the peak acceleration of the input seismic wave; The acceleration response of core-wall rock-fill dam has decreased in water condition, indicating the impoundment has changed the dynamic characteristics of the core-wall, reducing its acceleration response, the upper part of the dam decreases more obviously than the lower.(3)By comparing the results of large-scale shaking table model test, this chapter mainly studys the acceleration response characteristics of CFRD and compare the different characteristics of the core-wall rock-fill dam and concrete faced rockfill dam in the acceleration response.It has summarized the distribution of acceleration response of several concrete faced rock-fill dams along the direction of the dam height and the direction of the upstream and downstream and compared the acceleration response with or without water. The results show that:The seismic acceleration of concrete faced rock-fill dam has obvious amplification effect along the direction of the dam height, being the strongest in the dam top 1/4 area, and the "whiplash effect" is quite obvious; The amplification effect of the slope of the concrete faced rock-fill dam is obvious, and the acceleration response of the downstream dam slope is greater than that of the central line and the upstream dam slope; The acceleration magnification of the concrete faced rock-fill dam decreases with the increase of the peak acceleration of the input seismic wave; The acceleration response of concrete faced rock-fill dam has decreased in water condition, and the upper part of the dam decreases more obviously than the lower. The acceleration response of the concrete faced rock-fill dam and core-wall rock-fill dam along the direction of the dam height and the direction of the upstream and downstream is basically the same, just being different in the shape of the distribution of acceleration response and the rising trend, and the main reason leading to this difference is the different layout of the seepage control system of two types of dams. Acceleration response of concrete faced rock-fill dam and core-wall rock-fill dam in water condition will reduce, but the degree and mechanism is different. The main reason leading to the reduction of acceleration response of the core-wall rock-fill dam is that the impoundment has changed the dynamic characteristics of the core-wall, and the main reason leading to the reduction of acceleration response of the concrete faced rock-fill dam is the inhibition of concrete panel. Overall, the crest and upper slope is the largest region in acceleration response and is also the most prone to damage, so it’s important to strength the the seismic design of this region.(4)Based on the results of large-scale shaking table model tests, this chapter mainly studied the influence of valley shape on acceleration response and compared the acceleration response of main section and sub section of a concrete faced rock-fill dam located in a super wide valley, in the same time analyzing the effects of dam height on acceleration response. The results show that:The valley shape has a significant impact on the distribution of acceleration response. The acceleration response of the concrete faced rock-fill dam located in V-shaped valley is constrained obviously and the acceleration response distribution along the dam axis showed a significant inverse V shape. The acceleration response distribution along the dam axis of the dam located in wide valley exists a platform of maximum acceleration response in the middle of the valley, and the dam located in wider valley has a longer platform; The acceleration response of main section is larger than that of sub section and the main section’s "whiplash effect" is more obvious; The current results indicate that the higher the concrete faced rock-fill dam is, the more obvious the "whiplash effect" will be. Overall, the acceleration response of the dam in the central part of the river is the strongest, and is the key area of earthquake protection.(5)By using the combination of model test and numerical analysis, this chapter studied the acceleration response of earth-rock-fill dam under different input seismic waves and analyzed the ground motion input’s influence on acceleration response of earth-rock-fill dam. It studied the acceleration response of earth-rock-fill dam under different input seismic waves from the perspective of model tests. It studied acceleration response, dynamic shear stress, seismic residual deformation, dynamic stability and dam slope seismic safety of high earth-rock-fill dam under site wave, specification wave and measured wave from the numerical analysis perspective. The results show that:From the perspective of model tests, the acceleration response of site wave is obviously higher than that of the specification wave. From the perspective of numerical analysis, the acceleration response of site wave is larger than that of the specification wave and the measured wave, which is related to the spectrum characteristics of the three waves. Overall, the calculation results of the site wave are relatively conservative, and meeting the results of the specification wave is the minimum requirement, and there are limitations in the selection of measured waves. The relevant laws and conclusions can provide technical basis for engineering seismic design.(6) By actual damage analysis and model test, this chapter studied and summarized the characteristics of earthquake damage and seismic failure mode and and put forward the corresponding measures in the earthquake, and through the model test verifys the protective effects of seismic measures of dam slope. The results show that:The main form of earthquake damage of concrete faced rock-fill dam is loose particles and the rolling stones, gradually developed into a local shallow sliding, and then expanded into a large area of surface sliding, with the slide depth increasing and the crest collapsed, the concrete panel damaged. The process mainly developed from local landslide to large area’s surface slide until dam failure; The results of shaking table model test show that concrete stone masonry and concrete stone masonry plus frame beams have a better seismic effect than the stone revetment. |
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