动载荷下双孔平行地铁隧道下穿高速公路稳定性研究

发布时间：2018-03-26 19:10

本文选题：双孔隧道　切入点：动载荷　出处：《重庆大学》2015年硕士论文

【摘要】：随着城市化快速发展,城市交通形式已变得复杂多样,城市地铁和城市高速公路在一线、二线城市迅速兴建,带来了两者重叠交错施工的难题。本文以重庆轨道环线工程区间下穿内环高速公路为研究背景,采用理论分析和Flac3D数值软件模拟相结合的方法的研究方法,对双孔水平地铁隧道下穿施加重车动载荷的高速公路的施工稳定性及影响因素进行了分析计算。文章重点分析了隧道埋深,双孔净距和双孔异步开挖间距三个因素对高速公路路面、围岩及隧道的稳定性进行了研究,在此基础上引入松动圈理论对开挖后的双孔平行地铁隧道的塑性区分布规律进行了分析,对相似工程的施工有一定的借鉴和指导意义。主要研究成果如下:①在高速路面施加动载荷情况下,下穿隧道的开挖对上覆高速路面的沉降影响并非是随着埋深的不断增加而增加或减小,而是存在一个阀值,这个阀值约为三倍隧道直径D,当埋深小于3D时动载荷下路面沉降随埋深的增大而增加,大于这个阀值,埋深越大对路面沉降的影响越小;此外埋深越大,动载荷对隧道结构的稳定性影响越小。②双孔下穿隧道的净距是影响开挖后围岩稳定性和路面沉降的一个重要因素。双孔隧道净距较小时,两隧道的影响范围相互叠加,加剧了路面、围岩的沉降,最大沉降点位于两洞中心处顶端,沉降槽呈“碗状”;当净距大于1.5D时,最大沉降值随净距的增加呈线性减小,隧道内最大主应力呈减小趋势,但路面沉降槽范围扩大;当双孔净距大到一定程度时,两洞几乎不存在叠加效应,路面最大沉降点也将位于两洞拱顶正上方的路面沉降点。③为缩短工期,提高施工效率,节约施工成本设计了双孔隧道异步开挖工序。双孔隧道的掌子面异步间距对上覆路面的沉降影响几乎为零,但对于洞内稳定性影响较大;先行开挖的隧道掌子面由于后行隧道的开挖受到二次扰动,其应力重新分布,沉降值略大于后行开挖的隧道;随着异步间距的增大,双洞的相互扰动逐渐减小,逐渐接近于单洞分别开挖的应力分布④通过层次分析法对埋深、净距、异步开挖间距三个因素对路面沉降和洞内拱顶沉降进行权重分析,结果证明埋深对路面沉降的影响权重最大,为0.6025;而净距对洞内沉降的影响权重最大,为0.8275;异步开挖掌子面间距对路面和洞内沉降的影响权重很小,几乎可以忽略。⑤引入松动圈理论,采用卡斯特奈(Kastner)公式,并将其耦合到FLAC3D数值模拟软件中计算得出双孔隧道松动圈半径在动载荷影响下随埋深呈现线性变化关系。
[Abstract]:With the rapid development of urbanization, the forms of urban transportation have become complex and diverse. This paper takes Chongqing Railway Link Project as the research background, adopts the method of combining theoretical analysis and Flac3D numerical simulation. This paper analyzes and calculates the construction stability and influencing factors of the expressway with double hole horizontal subway tunnel under which the vehicle dynamic load is aggravated. The stability of highway pavement, surrounding rock and tunnel is studied by three factors: double hole spacing and asynchronous excavation spacing. On the basis of this, the plastic zone distribution of the two-hole parallel subway tunnel after excavation is analyzed by introducing the loosening circle theory. The main research results are as follows: 1 under the condition of dynamic load on high speed pavement, The influence of the excavation of the underpass tunnel on the settlement of the overlying high speed pavement is not increased or decreased with the increasing of the buried depth, but there is a threshold value. The threshold value is about three times the diameter of the tunnel. When the buried depth is less than 3D, the pavement settlement increases with the increase of the buried depth, the larger the threshold, the smaller the influence of the buried depth on the pavement settlement, and the greater the buried depth, The smaller the influence of dynamic load on the stability of tunnel structure, the smaller the net distance of tunnel under double hole is, which is an important factor to influence the stability of surrounding rock and the settlement of pavement after excavation. When the net distance of tunnel is small, the influence range of the two tunnels is superimposed on each other. The maximum settlement point is located at the top of the center of the two holes, and the settlement trough is "bowl shaped". When the net distance is greater than 1.5 D, the maximum settlement value decreases linearly with the increase of the net distance, and the maximum principal stress in the tunnel tends to decrease. But the range of pavement settlement trough is enlarged, when the net distance between two holes is large to a certain extent, there is almost no superposition effect between the two holes, and the maximum settlement point of the road surface will also shorten the time limit and improve the construction efficiency by taking the pavement settlement point just above the arch roof of the two holes as the time limit. The asynchronous excavation procedure of double-hole tunnel is designed to save construction cost. The asynchronous distance between the face of the double-hole tunnel has almost zero effect on the settlement of the overlying pavement, but has a great effect on the stability of the tunnel. Due to the second disturbance in the excavation of the tunnel surface, the stress is redistributed and the settlement value is slightly larger than that of the tunnel excavated after the tunnel is excavated, and with the increase of the asynchronous distance, the mutual disturbance of the two holes decreases gradually. The stress distribution, which is gradually close to the single hole excavation, is analyzed by AHP to analyze the three factors of buried depth, net distance and asynchronous excavation spacing on the road surface settlement and the vault settlement in the tunnel. The results show that the influence weight of buried depth on pavement settlement is the largest (0.6025), while the influence weight of net distance on tunnel settlement is the largest (0.8275), and the influence weight of surface spacing of asynchronous excavation on pavement and tunnel settlement is very small. The loosening circle theory can be neglected and the Kastner formula is adopted and coupled to the FLAC3D numerical simulation software to calculate the linear relationship between the loosening ring radius of the two-hole tunnel and the buried depth under the influence of dynamic load.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U231;U451

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