| Due to the unique geographical location, the tectonic activity is relatively active and earthquakes are frequently occurred in China. After the earthquake, the transportation interruption caused by the damage of retaining structure on highway slope brings great distress to the earthquake relief work, increasing the difficulty of the rescue, causing the secondary damage. These lessons are a wake-up call for the research on seismic shock theory, warning us to improve the anti-seismic consciousness. Meanwhile, with the western development strategy in western China, more and more highway construction are built in the mountainous and high intensity seismic region in western China. The high and steep roads bring large numbers of the construction of retaining structure. Since the retaining wall is an important part of retaining structure, the study on the seismic design of retaining wall is particularly important. Only by fully realizing the dynamic response rules of retaining wall under earthquake can we understand its failure mechanism and direct the seismic design of retaining wall.The current researches on the dynamic response of retaining wall under earthquake are mainly divided into shaking table model test and numerical simulation method. Both two methods have their own advantages and disadvantages and many scholars have researched on their application. In order to analyze comparatively and verify mutually, this paper analyzes and researches the seismic dynamic response of retaining wall under earthquake by adopting the combined method of shaking table model test and numerical simulation. The paper mainly analyzes the influence of different seismic wave intensity (the corresponding earthquake intensity is 6,7,8,9)and different seismic wave types on retaining wall dynamic response by using model test and researches the distribution rules of horizontal seismic action’s amplification effect along the wall height. The reliability of the model test results is proved and the internal stress and strain of retaining wall are analyzed by the numerical simulation. And according to the test results, the distribution coefficients’computational formula of horizontal seismic action along wall height is summarized.The composition and the basic parameters of the earthquake simulation shaking table used in the test are briefly introduced in the paper. According to the test objective, the testing program is designed from the following aspects:similarity relation design, retaining wall model design, monitoring scheme design, model filling, selection of suitable earthquake wave, determination of wall filler and confirmation of loading system. According to the loading scheme, the dynamic response of the retaining wall under different working conditions is studied and the monitoring data is collected and analyzed. According to the statistical data, we find that the distribution of horizontal seismic action along retaining wall is not linear. The acceleration peak of filling behind retaining wall grows slowly from the end of the wall. The acceleration speed grows when the wall height is from 0.4H to 0.6H and it reaches the maximum to the top of the wall. The acceleration amplification coefficient distributes from 1.617 to 1.941. The amplification effect of horizontal earthquake is inversely proportional to the input acceleration peak value. The larger the input acceleration peak value is, the smaller the amplification effect of horizontal earthquake is. Moreover, the variation of amplification coefficient is also influenced by the type of seismic wave. However, the influence is greatly random and the influence degree decreases with the increase of acceleration peak value.The nonlinear dynamic response analysis on same retaining wall is conducted by adopting the software FLAC3D based on finite difference method. Compared the increase of stress and strain in the filled soil induced by the earthquake. Besides, the plastic-zone analysis of retaining wall model is conducted and the reason why the seismic action amplification coefficient decreases with the increase of the input seismic acceleration peak value is explained. According to the monitoring data, the rule is analyzed that the acceleration peak of filling behind retaining wall grows slowly along wall at first and then rapidly increase at the height of 0.5H-0.7H and the amplification coefficients are distributed between 1.659 and 1.881. This result is broadly similar to the model test, only differing in the location where the acceleration obviously amplify. The data accuracy and feasibility of the two methods are verified by the comparative analysis. Studied the effects on the distribution of horizontal earthquake action by changing the retaining model height. The distribution of horizontal earthquake action of different retaining wall height is similar, the height of retaining wall greater, the amplification effect of earthquake stronger.Based on the test data of the shaking table model, the paper studies on the variation of horizontal seismic acceleration amplification coefficients and the variation curve of seismic acceleration amplification coefficients under different seismic intensity is generalized as the curve of maximum value and the curve of mean value. Taking certain risk factor and practicality into consideration, a curve between the maximum value and mean value is chosen as the distribution coefficient curve of the horizontal seismic action along the wall height. According to the curve form, the distribution coefficient curves of horizontal seismic action under four kinds of seismic wave intensities are divided into two groups:high intensity group and low intensity group. The two groups are different in value and distribution type. At the same height, the amplification coefficients corresponding to the high intensity group are smaller than the coefficients of the low intensity group. The curve of high intensity group increases rapidly at the 0.6H, while the low intensity group increases rapidly at the 0.4H.Choose appropriate curves from the two curve groups of high intensity and low intensity respectively as the representatives to conduct curve-fitting. Based on this, summarize the calculation formula of the distribution coefficient of the horizontal seismic action along the retaining wall height, and make a contrast between the formulas in new standard and old standard. The calculation formula of high intensity group is similar to that of new standard. Both are expressed by segmented function. In the section of 0-0.6H, the expressions are same; in the section of 0.6H-H, the value of high intensity group is slightly smaller than the value of new standard formula. The formula of low intensity group adopts polynomial form and its value is bigger than that of the new standard but smaller than that of the old standard. At the same height, the distribution coefficient value of horizontal seismic action of the four calculation formulas are listed from large value to small value as old standard, low intensity group, new standard and high intensity group. When we use the calculation method in this paper to conduct seismic design, we divide the intensity groups according to the intensity of highway construction in this region at first and then choose the corresponding calculation formula to calculate. Compared with the previous standards, this calculation formula rationally considers the influence of seismic wave intensity on horizontal amplification effect, so that its calculation results are more consistent with engineering practice. |
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