薄层破碎硬质岩隧道（群）施工对上部关键结构的影响研究

发布时间：2018-04-04 09:57

本文选题：薄层破坏硬质岩　切入点：离散元法　出处：《西南交通大学》2015年硕士论文

【摘要】：本文主要研究内容依托于贵阳龙洞堡机场隧道项目,该隧道穿越薄层破碎硬质岩地层,围岩中发育有较多层理、节理等结构面,而围岩受扰动后很容易沿结构面发生位移或破坏。本文采用3DEC离散元法,主要研究了隧道开挖对地表沉降和上部建筑结构的影响。由本文研究内容,可以得出如下结论：(1)在薄层破碎硬质岩体中,隧道施工引起的地表沉降的分布规律除受施工因素的影响外,同时还受岩块性质、结构面力学性质和分布形式等环境的影响,其中结构面的影响主要有：由于结构面强度和稳定性要比岩石低很多,隧道开挖后容易沿薄弱结构面发生变形或破坏；地层层理的倾角不同,则沉降槽中心相对于隧道中心的位置也不同；节理通缝分布时,地表沉降会在洞周附近节理面对应地表处产生很大的突变,而节理错缝分布时,地表沉降变化规律整体上与连续介质中很相似,地表沉降横向分布曲线大致可以用正态曲线描述,符合Peck公式,地表沉降沿纵向大致分为三个区一一前期沉降区、快速沉降区以及沉降收敛区。(2)隧道开挖引起的地表位移,如地表均匀沉降、地表倾斜、地表曲率和地表水平位移等,都会导致结构的变形和应力重分布,影响结构的稳定性,严重的导致结构开裂,甚至破坏。建筑结构的破坏模式与建筑的结构类型、处于沉降槽的位置等有关。为了保证建筑结构正常使用和防止结构破坏,一些建筑相关规范给出了建筑结构的变形和应力的控制标准,而我国城市地铁项目中通常30mm的地表沉降作为控制标准,但是此标准是根据工程经验得出的,并且有一定的适用范围,针对具体工程我们可以通过计算确定地表沉降控制标准。(3)基于龙洞堡机场隧道项目,运用3DEC离散元软件研究了隧道开挖过程对高架桥和地下停车场的影响。一般来说,建筑基础距离沉降槽中心的位置越近受到的影响越大；相对CRD法,双侧壁导坑法对隧道上部结构影响更小；辅助工法能控制地层位移和减小对结构的影响。具体工程中一般应根据工程经验、数值模拟或模型实验等方法确定施工措施,并根据现场监测结果及时调整。(4)基于龙洞堡机场隧道工程,经计算将隧道开挖下穿高架桥的过程中地表沉降的控制标准定为25mm。结合数值模拟结果和现场实测数据分析,经验算当采用设计要求进行隧道施工时,地表沉降、结构变形和应力均可满足控制标准。
[Abstract]:The main research content of this paper is based on the Longdongbao Airport Tunnel Project in Guiyang, which passes through thin layer broken hard rock strata, and there are more bedding and joints in the surrounding rock.But the surrounding rock is easy to displace or destroy along the structure surface after disturbance.In this paper, 3DEC discrete element method is used to study the influence of tunnel excavation on surface settlement and superstructure.From the research contents of this paper, we can draw the following conclusion: (1) in thin layer broken hard rock mass, the distribution law of ground subsidence caused by tunnel construction is not only affected by construction factors, but also affected by the properties of rock block.The influence of mechanical properties and distribution form of structural plane is mainly as follows: because the strength and stability of structural plane are much lower than that of rock, the tunnel is prone to deformation or failure along the weak structural plane after excavation;If the dip angle of stratigraphic strata is different, the position of the center of the subsidence trough relative to the center of the tunnel will be different, and when the joint joint is distributed, the ground subsidence will produce a very big mutation in the joint face of the surface near the hole, and when the joint is staggered,The variation law of surface subsidence is similar to that in continuous medium, and the lateral distribution curve of surface subsidence can be described by normal curve, which accords with Peck formula.The surface displacement caused by the excavation of the tunnel, such as uniform settlement, slope, curvature and horizontal displacement, will lead to the deformation and stress redistribution of the structure, which will affect the stability of the structure.Serious structural cracking, or even damage.The failure mode of building structure is related to the type of structure and the position of settlement tank.In order to ensure the normal use of the building structure and prevent the structural damage, some building codes give the control standard of the deformation and stress of the building structure, and the ground subsidence of 30mm is usually used as the control standard in the urban subway projects in China.However, this standard is based on engineering experience and has a certain scope of application. For specific projects, we can determine the control standard of surface subsidence by calculation. 3) based on the Longdongbao Airport Tunnel Project.The influence of tunnel excavation on viaduct and underground parking lot is studied by 3DEC discrete element software.Generally speaking, the closer the position of building foundation to the center of settlement trough is, the greater the influence is; compared with the CRD method, the double-sidewall method has less influence on the superstructure of tunnel; the auxiliary method can control the displacement of the stratum and reduce the influence on the structure.Construction measures should be determined according to engineering experience, numerical simulation or model experiment, and adjusted timely according to site monitoring results.) based on Longdongbao Airport Tunnel Project,Through calculation, the control standard of ground subsidence in the course of tunnel excavation through viaduct is determined to be 25mm.Based on the analysis of the numerical simulation results and the field measured data, when the design requirements are adopted for tunnel construction, the ground subsidence, structural deformation and stress can meet the control standards.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U451;U455

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