發(fā)布時間：2018-05-03 13:24

  本文選題：軟弱層 + 土層特性��； 參考：《湖南工業(yè)大學(xué)》2017年碩士論文

【摘要】：含有軟弱層的場地是我國沿海地區(qū)常見的一種場地類型,其作為一種特殊場地一直是地震工程學(xué)領(lǐng)域研究的重點,已有的地震災(zāi)害調(diào)查及場地分析均表明土體結(jié)構(gòu)中軟弱層的存在對場地地震效應(yīng)有著不可忽略的影響,所以對含軟弱層的場地進行地震效應(yīng)分析,無疑對結(jié)構(gòu)抗震設(shè)計具有重要意義。本文采用尚守平等提出的基于阻尼的滯回模型,應(yīng)用一維真非線性場地反應(yīng)分析方法,對含有軟弱層的場地展開分析,主要研究了軟弱層的埋深、厚度、剪切波速、阻尼比和動剪模量比這5種因素變化對場地峰值加速度和場地反應(yīng)譜的影響規(guī)律。研究結(jié)果表明:1、軟弱層的存在使得場地加速度峰值發(fā)生突變,隨著軟弱層埋深、厚度、剪切波速、阻尼比和動剪模量比的不同,這種突變可能使得地面峰值加速度增大或減小。對于給定的軟弱層埋深、厚度、剪切波速、阻尼比和動剪模量比,隨輸入地震動幅值的增大,地面峰值加速度增大,加速度效應(yīng)系數(shù)沒有明顯規(guī)律;對于給定的地震動,地面峰值加速度隨軟弱層埋深、厚度的增大而減小,隨剪切波速的增大而增大,隨阻尼比和動剪模量比的依次變化在增大,由此表明深厚的軟弱層對場地具有顯著的減震作用,其埋深越深,厚度越大,剪切波速越小,減震效果越明顯。2、軟弱層的存在使得場地反應(yīng)譜特征周期延長,長周期段曲線升高并出現(xiàn)多峰值現(xiàn)象,有無軟弱層的場地反應(yīng)譜差值比遠大于工程可接受的誤差范圍20%,且在本文算例中,最大反應(yīng)譜差值比已達到18.0倍;軟弱層所引起的場地反應(yīng)譜差值比曲線隨結(jié)構(gòu)周期的增大先升高后降低,存在一個對應(yīng)著最大反應(yīng)譜差值比的特征周期;軟弱層的埋深、厚度、剪切波速、阻尼比和動剪模量比是決定軟弱層對場地反應(yīng)譜強烈程度的主要因素,而輸入的地震波特性與地震動幅值對含軟弱層場地的反應(yīng)譜的影響規(guī)律則不明顯。
[Abstract]:The site containing weak layer is a common site type in coastal areas of China. As a special site, it has always been the focus of research in the field of seismic engineering. The existing seismic disaster investigation and site analysis show that the existence of weak layer in soil structure has an important influence on site seismic effect, so the seismic effect of site with weak layer is analyzed. Undoubtedly, it is of great significance to the seismic design of structures. In this paper, the hysteretic model based on damping proposed by Shang Shouping and the method of one-dimensional true nonlinear site response analysis are used to analyze the site with weak layer. The buried depth, thickness and shear wave velocity of weak layer are studied. The effects of damping ratio and dynamic shear modulus ratio on the peak acceleration and site response spectrum are investigated. The results show that the existence of weak layer makes the ground acceleration peak change. With the difference of buried depth, thickness, shear wave velocity, damping ratio and dynamic shear modulus ratio, this sudden change may increase or decrease the peak acceleration of the ground. For a given depth, thickness, shear wave velocity, damping ratio and dynamic shear modulus ratio, the peak acceleration of the ground increases with the increase of the amplitude of the input ground motion, and the acceleration effect coefficient is not obvious. The peak acceleration decreases with the depth and thickness of the soft layer, increases with the increase of shear wave velocity, and increases with the change of damping ratio and dynamic shear modulus ratio. The deeper the depth, the greater the thickness, the smaller the velocity of shear wave, the more obvious the seismic absorption effect is. The existence of weak layer makes the characteristic period of site response spectrum longer, the curve of long period increases and the phenomenon of multi-peak value appears. The difference ratio of site response spectrum with or without weak layer is much larger than that of engineering acceptable error range of 20, and the maximum response spectrum difference ratio has reached 18.0 times in the example in this paper. The difference ratio curve of site response spectrum caused by weak layer increases first and then decreases with the increase of structural period, and there exists a characteristic period corresponding to the maximum difference ratio of response spectrum, the buried depth, thickness, shear wave velocity of weak layer, The damping ratio and the dynamic shear modulus ratio are the main factors that determine the strong degree of the response spectrum of the weak layer to the site, but the influence of the input seismic wave characteristics and the amplitude of the ground motion on the response spectrum of the site containing the weak layer is not obvious.
【學(xué)位授予單位】：湖南工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU435

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本文編號：1838648