本文選題：地震動力響應特征　切入點：加速度放大系數(shù)　出處：《西南交通大學》2013年碩士論文　論文類型：學位論文

【摘要】：我國是一個多山的國家,地震活動頻繁,近幾年各大地震所誘發(fā)的邊坡失穩(wěn)破壞如崩塌、泥石流、滑坡等地質災害是山區(qū)常見的失穩(wěn)破壞模式。目前對邊坡失穩(wěn)破壞的研究大多是從定性的角度來對滑動機理進行分析的,還需在數(shù)值模擬、理論計算等方面進行進一步研究,以評價邊坡的地震動力響應穩(wěn)定性。故積極開展邊坡地震動力響應特征研究分析,對提高地震高發(fā)區(qū)及高烈度區(qū)的邊坡治理質量與安全運行具有非常重要的理論意義和工程價值。 本文以青海玉樹機場路一不穩(wěn)定邊坡為例,并將其作為數(shù)值分析原型。通過FLAC3D有限差分軟件,采用時程分析法,分別計算邊坡在地震峰值加速度、持時、波譜特性,巖體粘聚力及彈性模量等參數(shù)不同取值下的加速度動力響應特征,進而得到其在坡體內分布規(guī)律的擬合公式。再進行擬靜力法改進,即在現(xiàn)有擬靜力法中考慮到加速度隨邊坡高度變化的非線性動力特征,從而計算出安全系數(shù),評價邊坡地震穩(wěn)定性。最后分析同時考慮水平和豎向地震加速度作用條件下的邊坡動力響應特征,為進一步分析地震穩(wěn)定性奠定良好的基礎。本文取得的主要研究成果有： (1)在水平地震波單獨作用下,邊坡對輸入地震波存在顯著的垂直放大效應和水平放大效應。地震峰值加速度放大系數(shù)隨高程增加逐漸增大,一般在坡頂處達到最大值；同一高程處,由坡內至坡面,加速度放大系數(shù)呈增大趨勢,在坡面處存在顯著的臨空面放大效應；并對加速度放大系數(shù)在邊坡高程方向上的變化規(guī)律進行了公式擬合； (2)在加速度動力響應分析的基礎上,對擬靜力法進行了改進,改進的思想為在評價邊坡地震穩(wěn)定性時,考慮到邊坡對地震加速度的非線性放大效應,采用擬合公式進行地震影響系數(shù)的計算,最后通過實例驗證得出,改進擬靜力法所計算的安全系數(shù)小于現(xiàn)有擬靜力法,說明改進擬靜力法更安全； (3)在水平和豎向地震波共同作用下,邊坡對輸入地震波存在顯著的垂直放大效應和臨空面放大效應。地震峰值加速度隨高程增加逐漸增大,邊坡底部放大效應不顯著,增幅較小,邊坡頂部會達到一個相對較顯著的放大效應；同一高程處,由坡內至坡面,加速度放大系數(shù)呈增大趨勢,在坡面處達到最大值。且通過加速度放大系數(shù)在坡體內的分布規(guī)律可知：在水平和豎向加速度共同作用下,邊坡對地震加速度的水平放大效應較垂直向放大效應顯著。
[Abstract]:China is a mountainous country with frequent seismic activities. In recent years, slope instability caused by major earthquakes, such as collapse and debris flow, Landslide and other geological hazards are common failure modes in mountain areas. At present, most of the researches on slope instability and failure are based on qualitative analysis of sliding mechanism, and need to be further studied in numerical simulation, theoretical calculation and so on. In order to evaluate the stability of the seismic dynamic response of the slope, the research and analysis of the characteristics of the seismic dynamic response of the slope are carried out actively. It is of great theoretical significance and engineering value to improve the slope treatment quality and safe operation in the areas with high earthquake incidence and high intensity. This paper takes the unstable slope of Yushu Chishang Road in Qinghai as an example and takes it as the prototype of numerical analysis. By using FLAC3D finite difference software and time history analysis method, the peak acceleration, duration and spectrum characteristics of the slope are calculated respectively. The acceleration dynamic response characteristics of rock mass under different parameters, such as cohesive force and elastic modulus, are obtained, and the fitting formula of the distribution law of rock mass in slope is obtained, and then the pseudostatic method is improved. That is to say, the nonlinear dynamic characteristics of acceleration varying with slope height are taken into account in the existing pseudostatic method, and the safety factor is calculated. Finally, the dynamic response characteristics of slope under horizontal and vertical seismic acceleration are taken into account, which lays a good foundation for further analysis of seismic stability. The main research results obtained in this paper are as follows:. 1) under the action of horizontal seismic wave alone, the slope has significant vertical amplification effect and horizontal amplification effect on the input seismic wave. The peak acceleration magnification coefficient increases gradually with the elevation increasing, and generally reaches the maximum at the top of the slope; At the same elevation, from the slope to the slope, the acceleration magnification coefficient tends to increase, and there is a significant magnification effect on the slope surface, and the law of the variation of the acceleration magnification factor in the direction of the slope elevation is fitted. 2) based on the analysis of the acceleration dynamic response, the pseudostatic method is improved. The improved idea is to take into account the nonlinear amplification effect of the slope seismic acceleration when evaluating the seismic stability of the slope. The fitting formula is used to calculate the seismic influence coefficient. Finally, the safety factor calculated by the improved pseudo-static method is less than that of the existing pseudo-static method, which shows that the improved pseudo-static method is safer. 3) under the joint action of horizontal and vertical seismic waves, the slope has significant vertical amplification effect and near-empty surface amplification effect on the input seismic wave. The peak acceleration of the earthquake increases gradually with the increase of height, but the amplification effect at the bottom of the slope is not significant. At the same elevation, the acceleration magnification coefficient increases from the slope to the slope. Through the distribution of acceleration magnification coefficient in the slope, it can be seen that the horizontal amplification effect of the slope on seismic acceleration is more significant than that of vertical acceleration under the combined action of horizontal and vertical acceleration.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU435

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