黄土隧道环向局部湿陷的围岩力学特性研究

发布时间：2018-06-16 23:00

本文选题：黄土隧道工程 + 围岩力学特性　；参考：《西南交通大学》2017年硕士论文

【摘要】：近百年,随着我国基础建设的发展,高速及专用铁路、公路、城市轨道交通建设项目日益增多,黄土地区也修建了大量的铁路、公路等隧道工程,积累了丰富工程经验的同时,也面临着一系列亟待解决的问题。黄土作为一种极具特色的特殊土,它的湿陷性是困扰工程建设的一个难题,并且随着黄土含水率的增大,具有一定的突发性。在隧道建设中出现围岩局部湿陷的情况会引起湿陷部位衬砌结构的应力集中,并附带产生偏压的现象,造成衬砌开裂、起皮、掉块、大变形等不利影响。因此,论文以蒙华铁路的隧道建设为研究对象,通过现场调研、土工试验、模型试验以及数值模拟等手段,对以上问题展开了相关研究,得到成果如下:(1)通过现场调研得知不良的地形地质条件,如:发育的冲沟、土石分界等,在地下水和春冬冻融水的作用下都可能引发黄土隧道环向围岩的局部湿陷,致使黄土强度降低,衬砌结构承受荷载增加,引起隧道大变形、开裂等现象;(2)通过黄土的物理性质和力学性能的测试,可知该地区新黄土的颗粒比重大,主要成分为粉砂粒,内聚力较低,在水的作用下容易变成流塑状,结构受到破坏,导致力学性能降低;(3)通过数值模拟的手段,分析了黄土隧道围岩局部湿陷引起的地层沉降变化规律,从中得知,隧道上覆土层的沉降与湿陷区域的大小和厚度成正比;(4)从模型试验和计算结果中可以看出,拱顶局部区域黄土含水率增大湿陷过程中,影响最大的为拱顶和拱肩,其他位置受到的影响微弱,可忽略不计;右侧拱肩湿陷的情况,由模型试验和数值计算结果可知,影响最大的为右拱肩和右拱腰,但是其余位置也受到了一定的影响;右拱腰湿陷的情况下,影响最大的为右拱腰和右拱脚,右拱肩也受到了较大的影响,其余部位影响较小;(5)综合拱顶湿陷、拱肩湿陷、拱腰湿陷三种工况的模型试验和数值分析可知,拱肩湿陷的影响范围最大,对围岩环向局部湿陷较为敏感的部位为衬砌结构位于湿陷侧的拱肩和拱腰,拱顶和拱脚次之。
[Abstract]:In the last hundred years, with the development of our country's infrastructure, the construction projects of high-speed and special railways, highways and urban rail transit are increasing day by day, and a large number of tunnel projects, such as railways and highways, have also been built in the loess region, which have accumulated rich engineering experience at the same time. Also facing a series of problems to be solved. Loess is a special soil with special characteristics, its collapsibility is a difficult problem that puzzles engineering construction, and with the increase of loess moisture content, it has a certain degree of paroxysmal. The local collapse of surrounding rock in tunnel construction will lead to the stress concentration of lining structure in the collapsing position and the phenomenon of bias pressure, which will lead to the adverse effects of lining cracking, peeling, block dropping, large deformation and so on. Therefore, the paper takes the tunnel construction of the Monghua Railway as the research object, through the field investigation, the geotechnical test, the model test and the numerical simulation and so on, has carried on the related research to the above question. The results are as follows: 1) through on-the-spot investigation, we know that poor topographic and geological conditions, such as developed gullies, earth-rock boundaries, and so on, may lead to local collapses of surrounding rock around loess tunnels under the action of groundwater and spring and winter freezing and thawing water. By testing the physical properties and mechanical properties of loess, it can be seen that the grain density of new loess in this area is large and the main component is silt sand. Under the action of water, the cohesive force is relatively low, the structure is easily changed into fluid-plastic shape, and the structure is destroyed, which results in the reduction of mechanical properties. (3) by means of numerical simulation, the regularity of ground subsidence caused by local collapsing of surrounding rock of loess tunnel is analyzed, and it is known from the results. The settlement of the overlying soil layer of the tunnel is proportional to the size and thickness of the collapsing area. From the model test and calculation results, it can be seen that in the process of increasing the moisture content of loess in the local area of the arch roof, the greatest influence is on the arch roof and the arch shoulder. The influence of other positions is weak and negligible, and the results of model test and numerical calculation show that the right arch shoulder and the right arch waist have the greatest influence, but the other positions are also affected to some extent. The right arch waist and the right arch foot have the greatest influence when the right arch waist collapses, and the right arch shoulder is also greatly affected. The model test and numerical analysis show that the influence range of arch shoulder collapse is the largest, and the most sensitive part to the circumferential local collapse of surrounding rock is the arch shoulder and arch waist of lining structure located on the side of the collapse, followed by the arch top and arch foot.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451.2

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