超大断面新黄土隧道结构稳定性与基底湿陷性处理方法研究

发布时间：2018-01-06 01:06

本文关键词：超大断面新黄土隧道结构稳定性与基底湿陷性处理方法研究　出处：《兰州交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：在我国西部大规模的隧道施工建设中,大断面黄土隧道能够有效的缓解高密度的交通流量,势必将成为未来隧道结构形式的主流。黄土隧道在设计施工中,黄土作为一种特殊的土质,关键在于隧道开挖过程中如何确保围岩和衬砌结构的的稳定性,特别是当隧道处于湿陷性黄土地层中时如何对隧道地基进行加固,消除黄土湿陷性,保证隧道地基承载力满足设计要求。本文依托兰州榆定路大营黄土隧道为研究对象,基于通用有限元软件建模,结合特大断面黄土浅埋隧道的工程实例,分析了黄土隧道结构和围岩在开挖过程中的受力特点,研究了在黄土隧道中隧道地基采用无振动地基挤密加固新技术的应用,本文主要研究内容及研究结论如下:(1)通过对隧道CRD法施工的开挖模拟,分析了特大断面黄土隧道在开挖过程中的变形量和变形速率特点,结果表明已施做的初期支护和临时支撑能够很好的控制变形,当临时支撑拆除后,变形量和变形速率有增大的趋势,应及时施做二次衬砌。(2)大营村隧道二次衬砌结构稳定性分析表明,在地震和非地震两种情况下,拱脚部位均出现较大的应力集中现象,需要对隧道基地进行加固处理,以保证隧道结构安全和满足工后沉降要求。(3)通过对无振动黄土挤密加固技术的试验数据分析,提出了在进行黄土地基加固时的合理桩间距。试验表明,当桩间距不大于0.7m时,桩间土的湿陷系数、自重湿陷系数均小于0.015,消除了黄土的湿陷性,但桩间距与地基挤密系数之间并非呈正比关系。当桩间距为0.9m时,平均挤密系数与最小挤密系数才能同时满足《湿陷性黄土地区建筑规范》(GB50025—2004)规定的大于0.93、0.88的要求。(4)通过对工程试验中量测数据的分析,发现无振动黄土挤密加固技术在地基土体挤密处理范围内最底部1~1.5m处,有效挤密成桩直径小于设计桩径(仅为设计桩径的68.8%),桩底各桩间土平均挤密系数与最小挤密系数均小于《湿陷性黄土地区建筑规范》(GB50025—2004)规范规定的0.93、0.88的要求。
[Abstract]:In the large-scale tunnel construction in western China, large section loess tunnel can effectively alleviate the high density of traffic flow, which is bound to become the mainstream of tunnel structure in the future. The loess tunnel in the design and construction. Loess as a special soil quality, the key lies in how to ensure the stability of surrounding rock and lining structure during tunnel excavation, especially how to strengthen the tunnel foundation when the tunnel is in the collapsible loess stratum. To eliminate the collapsibility of loess and ensure that the bearing capacity of the tunnel foundation meets the design requirements. This paper relies on the Lanzhou Yudinglu Daying Loess Tunnel as the research object, based on the general finite element software modeling. Combined with the engineering example of loess shallow buried tunnel with large section, the stress characteristics of loess tunnel structure and surrounding rock during excavation are analyzed. This paper studies the application of the new technology of compaction and reinforcement of the tunnel foundation without vibration in the loess tunnel. The main contents and conclusions of this paper are as follows: 1) the excavation simulation of the tunnel CRD method is carried out. The characteristics of deformation and deformation rate of loess tunnel with large section during excavation are analyzed. The results show that the initial support and temporary bracing can control the deformation well when the temporary bracing is removed. The stability analysis of the secondary lining of Daying Village Tunnel shows that the stability analysis of the secondary lining structure of Daying Village Tunnel shows that under both earthquake and non-earthquake conditions, the deformation amount and deformation rate are increasing. There is a large stress concentration phenomenon in the arch foot, so it is necessary to reinforce the tunnel base. In order to ensure the safety of tunnel structure and meet the requirement of post-construction settlement. Based on the analysis of test data of non-vibratory loess compaction reinforcement technology, the reasonable pile spacing in loess foundation reinforcement is put forward. When the pile spacing is less than 0.7 m, the coefficient of collapsibility of soil between piles is less than 0.015, which eliminates the collapsibility of loess. But the pile spacing is not proportional to the compaction coefficient of the foundation, when the pile spacing is 0.9m. The average compaction coefficient and the minimum compaction coefficient can meet the requirements of < Building Code for collapsible Loess areas > GB50025-2004 > > 0.93 at the same time. Based on the analysis of the measured data in the engineering test, it is found that the vibration-free loess compaction reinforcement technology is at the bottom of 1 ~ 1.5 m in the compaction treatment range of foundation soil. The diameter of the effective compaction pile is smaller than that of the designed pile diameter (only 68.8% of the designed pile diameter). The average compaction coefficient and the minimum compaction coefficient of soil at the pile bottom are less than the requirements of 0.93 ~ 0.88 stipulated in < Building Code for collapsible Loess areas > GB50025-2004).
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451;U455.4

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