【摘要】：隨著地下軌道交通的快速發(fā)展,地鐵列車荷載引發(fā)的土體振動(dòng)和變形成為影響地鐵運(yùn)營安全的重要因素。目前關(guān)于動(dòng)荷載作用下黃土動(dòng)力特性和變形研究多基于地震或震陷。與地震荷載相比,地鐵列車荷載具有小幅值、長持續(xù)時(shí)間等特點(diǎn),而對于地鐵列車荷載長期作用下黃土的動(dòng)力特性和變形研究相對較少。基于以上原因,本文以西安地鐵四號(hào)線為工程背景進(jìn)行了以下研究:1)通過振動(dòng)三軸試驗(yàn),研究非飽和黃土的動(dòng)應(yīng)力—?jiǎng)討?yīng)變和動(dòng)應(yīng)力—?dú)堄鄳?yīng)變關(guān)系,得到:在同一動(dòng)應(yīng)變之下圍壓、固結(jié)應(yīng)力比越高,動(dòng)應(yīng)力幅值越大。2)通過循環(huán)三軸試驗(yàn),得到隨著動(dòng)應(yīng)力幅值的增加,非飽和黃土殘余應(yīng)變也隨之增加。3)ABAQUS數(shù)值分析結(jié)果表明:豎直方向振動(dòng)響應(yīng)大于水平方向振動(dòng)響應(yīng);地層的振動(dòng)響應(yīng)大于地表振動(dòng)響應(yīng);地表振動(dòng)響應(yīng)在距隧道軸線一定水平距離會(huì)出現(xiàn)“局部放大”現(xiàn)象;地層振動(dòng)響應(yīng)在地表附近和隧道鄰近區(qū)域出現(xiàn)了“局部放大”現(xiàn)象;荷載頻率越低,地表的振動(dòng)響應(yīng)越大;在隧道鄰近區(qū)域之外的土體,頻率越低振動(dòng)響應(yīng)越大;隧道鄰近區(qū)域的土體,振動(dòng)響應(yīng)規(guī)律各不相同,高頻荷載的加速響應(yīng)較大,低頻荷載的速度響應(yīng)較大,中間頻率荷載的位移響應(yīng)較大;速度為某一特定值時(shí),振動(dòng)響應(yīng)最大。4)使用Chai-Miura模型結(jié)合分層總和法研究了塑性沉降的累積效應(yīng),得出:隧道鄰近區(qū)域土體的靜動(dòng)偏應(yīng)力分布會(huì)發(fā)生突變;在地鐵行車荷載作用初期,地表沉降增長很快,增長速度隨著地鐵行車荷載循環(huán)作用次數(shù)的增加而逐漸變緩,沉降穩(wěn)定時(shí),地面的沉降最大值為18.0mm,隧道下方的沉降為1.07mm;塑性變形主要發(fā)生在隧道鄰近區(qū)域之中。
[Abstract]:With the rapid development of underground rail transit, the vibration and deformation of soil caused by train load have become an important factor affecting the safety of subway operation. At present, the dynamic characteristics and deformation of loess under dynamic load are mostly based on earthquake or earthquake subsidence. Compared with the seismic load, the subway train load has the characteristics of small value, long duration and so on. However, the dynamic characteristics and deformation of loess under the long term load of subway train are less studied. Based on the above reasons, this paper takes Xi'an Metro Line 4 as the engineering background to carry out the following research: 1) through the vibration triaxial test, the dynamic stress-dynamic strain and the dynamic stress-residual strain relationship of unsaturated loess are studied. It is obtained that the higher the consolidation stress ratio, the larger the amplitude of dynamic stress under the same dynamic strain. 2) through cyclic triaxial test, it is obtained that the amplitude of dynamic stress increases with the increase of dynamic stress amplitude. The residual strain of unsaturated loess also increases with it. 3) the results of ABAQUS numerical analysis show that the vertical vibration response is larger than the horizontal vibration response; The ground vibration response is larger than the surface vibration response, the ground vibration response will appear the "local amplification" phenomenon at a certain horizontal distance from the tunnel axis, the formation vibration response will appear the "local amplification" phenomenon near the ground surface and the tunnel adjacent area. The lower the load frequency, the greater the vibration response of the surface, and the larger the vibration response of soil outside the adjacent region of tunnel. In the adjacent region of tunnel, the vibration response of soil is different, the acceleration response of high frequency load is larger, the velocity response of low frequency load is larger, and the displacement response of intermediate frequency load is larger. When the velocity is a certain value, the vibration response is maximum. 4) the cumulative effect of plastic settlement is studied by using Chai-Miura model and stratified summation method. At the initial stage of the train load, the surface subsidence increases rapidly, and the growth rate is gradually slowed down with the increase of the number of times of the subway train load cycle. When the settlement is stable, the maximum settlement of the ground is 18.0mm. The settlement under the tunnel is 1.07mm; Plastic deformation mainly occurs in the adjacent region of the tunnel.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U451

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本文編號(hào)：2326220