管棚支护作用下隧道洞口段稳定性施工影响因素研究

发布时间：2019-05-20 09:14

【摘要】：隧道洞口段开挖作业是整个隧道施工过程中的咽喉工程,地位之重要不言而喻。然而洞口段围岩一般埋深较浅、风化严重,在开挖过程中经常会出现坍塌、冒顶等各种工程事故,所以隧道洞口段围岩的开挖稳定性研究一直是非常重要的课题之一。洞口段开挖稳定性影响因素有很多,即包括地质构造、围岩性质、地下水等非施工因素,也包括开挖方式、开挖进尺、预支护形式等施工因素。若洞口段施工时选择的开挖支护工法不合理,就会很容易造成工程事故,引发不必要的人员伤亡和财产损失。针对隧道工程中洞口段开挖稳定性等问题,本文重点研究在管棚支护作用下施工因素对其产生的影响。本文基于强度折减法基本原理,利用正交试验设计方法并结合有限元软件ABAQUS对管棚预支护作用下隧道洞口段的稳定性施工影响因素进行相关研究。在施工影响因素方面本文选择开挖方式、开挖进尺、初期支护厚度、管棚直径、管棚布置范围和管棚注浆半径等,并根据相关文献定出每种施工因素的取值范围,然后按照正交设计原理安排数值模拟方案。在此基础上应用有限元软件ABAQUS建立三维数值模型,分析各施工因素对隧道洞口段边仰坡稳定性和隧洞稳定性的影响。分析隧道洞口段边仰坡稳定性时,本文将选择稳定性安全系数作为分析指标,研究开挖方式等六种施工因素对稳定安全系数的影响程度,将其按数值的大小排列出来,以此得到影响边仰坡稳定性的关键施工因素;与此同时,分析每一因素的不同取值对稳定性安全系数的影响,得出稳定安全系数随各影响因素的不同取值而变化的趋势。分析隧洞稳定性时,本文选择拱顶处、拱底处、左拱腰处和右拱腰处四个位移测量点,然后以这些测量点的位移值作为分析指标,研究施工影响因素对各测点位移值的影响程度,将其按数值的大小排列出来,得到影响隧洞稳定性的关键施工因素;然后分析每一因素的不同取值对各测点位移的影响,得出各测点位移随影响因素不同取值而的变化趋势。
[Abstract]:The excavation operation of tunnel entrance section is the throat engineering in the whole tunnel construction process, and the importance of the position is self-evident. However, the surrounding rock of the entrance section is generally shallow and weathered seriously, and there are often various engineering accidents such as collapse and roof fall in the process of excavation, so the study on the excavation stability of the surrounding rock of the tunnel entrance section has always been one of the very important topics. There are many factors affecting the excavation stability of the entrance section, including geological structure, surrounding rock properties, groundwater and other non-construction factors, as well as excavation methods, excavation measures, pre-support forms and other construction factors. If the excavation and support method selected in the construction of the entrance section is unreasonable, it will easily cause engineering accidents and cause unnecessary casualties and property losses. In order to solve the problems of excavation stability in tunnel engineering, this paper focuses on the influence of construction factors on it under the action of pipe shed support. In this paper, based on the basic principle of strength reduction method, the influencing factors of tunnel entrance stability under the action of pipe shed pre-support are studied by using orthogonal experimental design method and finite element software ABAQUS. In the aspect of construction influencing factors, this paper selects excavation method, excavation scale, initial support thickness, pipe shed diameter, pipe shed layout range and pipe shed grouting radius, and determines the value range of each construction factor according to the relevant literature. Then the numerical simulation scheme is arranged according to the principle of orthogonal design. On this basis, the finite element software ABAQUS is used to establish a three-dimensional numerical model to analyze the influence of various construction factors on the stability of the side slope and the stability of the tunnel at the entrance of the tunnel. When analyzing the stability of the slope at the entrance of the tunnel, this paper selects the stability safety factor as the analysis index, studies the influence degree of six construction factors, such as excavation mode, on the stability safety factor, and arranges them according to the numerical value. The key construction factors affecting the stability of slope are obtained. At the same time, the influence of different values of each factor on the stability safety factor is analyzed, and the trend of the stability safety factor changing with the different values of each influencing factor is obtained. When analyzing the stability of the tunnel, this paper selects four displacement measuring points at the arch roof, the bottom of the arch, the left arch waist and the right arch waist, and then takes the displacement values of these measuring points as the analysis index. The influence degree of construction influencing factors on the displacement value of each measuring point is studied, and the key construction factors affecting the stability of the tunnel are obtained by arranging it according to the numerical value. Then the influence of the different values of each factor on the displacement of each measuring point is analyzed, and the changing trend of the displacement of each measuring point with the different values of the influencing factors is obtained.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455

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