發(fā)布時(shí)間：2019-03-22 06:34

【摘要】：隨著我國(guó)鐵路的快速發(fā)展，穿越黃土地層的隧道越來(lái)越多。隧道穿越黃土地區(qū)，由于黃土的特殊力學(xué)性質(zhì)，基底的承載力通常較難滿足結(jié)構(gòu)的受力性能。黃土隧道基底區(qū)域靜動(dòng)力特性，直接關(guān)系到隧道基底承載力是否能滿足結(jié)構(gòu)穩(wěn)定及運(yùn)營(yíng)安全的要求。同時(shí)，隧道底部基巖是整個(gè)隧道結(jié)構(gòu)的基礎(chǔ)，其在列車荷載長(zhǎng)期循環(huán)加、卸載作用下的性狀對(duì)隧道底部乃至整個(gè)隧道結(jié)構(gòu)受力都有顯著影響。隨著列車運(yùn)行速度的提高，對(duì)基底圍巖的變形也提出了更高的要求，因此研究在列車長(zhǎng)期荷載作用下的基底累計(jì)沉降變形顯得尤為重要。本文主要研究?jī)?nèi)容和成果如下： (1)在靜力分析方面對(duì)幾種確定圍巖壓力的傳統(tǒng)經(jīng)驗(yàn)理論方法進(jìn)行了對(duì)比分析，，分析得出全土柱法算出的基底圍巖壓力最大，卡柯公式最小。 (2)在靜力分析方面利用數(shù)值模擬的方法對(duì)隧道不同施工方法、隧道不同埋深、黃土本身力學(xué)參數(shù)(黏聚力、內(nèi)摩擦角)等方面對(duì)黃土隧道基底圍巖應(yīng)力進(jìn)行研究，得出不同施工方法對(duì)隧道基底圍巖豎向應(yīng)力的影響比較大；隨著隧道埋深的增大，隧道基底圍巖豎向應(yīng)力也增大；黃土本身力學(xué)參數(shù)(黏聚力、內(nèi)摩擦角)影響比較小可以忽略不計(jì)等規(guī)律。 (3)對(duì)隧道底部基巖動(dòng)力響應(yīng)特性進(jìn)行了系統(tǒng)的分析。用一個(gè)激勵(lì)函數(shù)的形式來(lái)模擬列車荷載，對(duì)四種不同時(shí)速(200km/h、250km/h、300km/h、350km/h)列車荷載進(jìn)行了數(shù)值模擬，分析了豎向位移加速度和豎向應(yīng)力隨四種不同列車時(shí)速荷載總用下的分布規(guī)律。數(shù)值模擬結(jié)果表明：隨著列車時(shí)速的增大，加速度峰值和基底總豎向應(yīng)力峰值都增大。 (4)對(duì)隧道基底圍巖在列車循環(huán)荷載作用下累計(jì)沉降進(jìn)行了分析，采用DingQing Li模型對(duì)累計(jì)塑性應(yīng)變進(jìn)行分析。對(duì)四種不同列車時(shí)速荷載作用下累計(jì)沉降值進(jìn)行了計(jì)算，得出運(yùn)營(yíng)初期累計(jì)沉降發(fā)展非常快，隨后累計(jì)沉降發(fā)展非常緩慢，最后趨于穩(wěn)定狀態(tài)，隧道基底累計(jì)沉降值隨著列車時(shí)速的提高而增大。
[Abstract]:With the rapid development of railway in China, more and more tunnels pass through loess stratum. Because of the special mechanical properties of loess, the bearing capacity of the foundation is usually difficult to meet the mechanical performance of the structure. The static and dynamic characteristics of loess tunnel basement region are directly related to whether the bearing capacity of tunnel basement can meet the requirements of structural stability and operation safety. At the same time, the bedrock at the bottom of the tunnel is the foundation of the whole tunnel structure. Under the long-term cyclic loading and unloading of the train load, the behavior of the foundation rock has a significant effect on the stress of the tunnel bottom and even the whole tunnel structure. With the increase of train running speed, the deformation of basement rock is required more and more. Therefore, it is very important to study the accumulative settlement deformation of basement under long-term load. The main contents and achievements of this paper are as follows: (1) in the aspect of static analysis, several traditional empirical methods for determining the pressure of surrounding rock are compared and analyzed, and the maximum pressure of the base rock calculated by the whole soil column method is obtained. The Carke formula is the smallest. (2) in the aspect of static analysis, numerical simulation is used to study the stress of surrounding rock of loess tunnel in different construction methods, different buried depth of tunnel, mechanical parameters of loess itself (cohesion force, internal friction angle) and so on. It is concluded that the influence of different construction methods on the vertical stress of surrounding rock of tunnel basement is relatively large. With the increase of tunnel depth, the vertical stress of surrounding rock of tunnel basement increases, and the influence of loess mechanical parameters (cohesion, internal friction angle) is negligible. (3) the dynamic response characteristics of bedrock at the bottom of tunnel are analyzed systematically. In the form of an excitation function, the train loads of four different speeds (200 km / h, 250 km / h, 300 km / h, 350 km / h) are numerically simulated. The distribution law of vertical displacement acceleration and vertical stress with the total speed load of four kinds of trains is analyzed. The numerical simulation results show that the peak acceleration and the peak value of the total vertical stress increase with the increase of train speed. (4) the accumulative settlement of surrounding rock of tunnel foundation under train cyclic load is analyzed, and the accumulative plastic strain is analyzed by DingQing Li model. The accumulative settlement values under four different train speed loads are calculated, and the results show that the accumulative settlement develops very quickly in the initial stage of operation, and then develops very slowly, and finally tends to a stable state. The cumulative settlement of tunnel substrate increases with the increase of train speed.
【學(xué)位授予單位】：石家莊鐵道大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U452.1

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