地铁暗挖车站STS管幕支护结构的力学性能研究

发布时间：2018-02-12 02:36

本文关键词： 超浅埋暗挖车站 STS管幕结构力学性能破坏特征计算方法　出处：《东北大学》2015年博士论文　论文类型：学位论文

【摘要】：传统管幕结构在钢管问仅用锁口进行连接,因此在施工过程中钢管受到的横向约束作用较弱,主要依靠管幕中钢管混凝土结构的纵向强度以及临时支护结构形成“棚架”支护体系。为此,管幕结构在开挖期间必须辅以密集的型钢支撑体系,且严格控制开挖步距,以确保管幕的承载能力和变形满足要求。繁琐的临时支护结构和复杂的力学体系转换对施工过程带来诸多不便。STS管幕结构在传统管幕的基础上利用高强度螺栓和翼缘板将相邻钢管连成整体,显著提高了其横向承载能力,施工过程中能减少繁杂的临时支撑。论文依托超浅埋STS管幕工法地铁暗挖车站为工程背景,以STS管幕结构为研究对象,采用模型试验、数值模拟以及理论分析的方法研究了施工过程中STS管幕结构的作用机制以及STS管幕构件的破坏模式和力学性能。主要研究和成果如下：通过对称集中荷载作用下STS管幕构件的力学性能试验,研究了STS管幕构件的工作机理及破坏模式,探讨了钢管间距、翼缘板厚度、横向连接方式、混凝土强度等级、螺栓间距、均布荷载等关键参数对其STS管幕构件承载力的影响。结果表明,下翼缘板焊接对STS管幕承载力的影响最为显著,而钢管间距、翼缘板厚度对STS管幕构件的承载力具有一定影响,上翼缘板焊接、混凝土强度等级以及通长螺栓等因素对STS管幕构件力学性能的影响较小。通过单点集中荷载作用下STS管幕构件的力学性能试验,研究了STS管幕构件在集中荷载作用下的破坏模式和工作机理,并探讨了不同横向连接方式、翼缘板厚度、混凝土强度等级等参数对STS管幕构件极限承载力和刚度的影响。结果表明,在集中荷载下STS管幕构件发生弯曲破坏,而下翼缘板焊接对其承载力影响最为显著,通长螺栓、混凝土强度、上翼缘板焊接等参数STS管幕构件承载力的影响较小,但是混凝土强度降低时构件延性得到改善,而上翼缘板焊接时构件的刚度提高较为明显。根据STS管幕构件的受力特点和破坏模式,确定了STS管幕构件在不同横向连接方式下的极限承载力计算公式,理论公式计算结果与试验结果吻合良好。根据STS管幕构件的受力和破坏特点,利用ABAQUS有限元程序建立了STS管幕构件的计算模型,研究其工作机理,并对翼缘板厚度、钢管壁厚、管间混凝土含量等参数对STS管幕构件的影响进行了分析。通过对不同翼缘板厚度和钢管壁厚的STS管幕构件进行计算,发现翼缘板厚度和钢管壁厚之比过大或过小均会影响STS管幕试件的破坏形式,得出二者比值在1.0-1.3之间较为合理,钢管和翼缘板能够同时发生屈服,不仅充分发挥了二者的材料性能,还能改善STS管幕构件的延性。二者比值小于1.0时,只有翼缘板达到屈服强度；而值大于1.3时,只有钢管达到屈服强度。
[Abstract]:The traditional pipe curtain structure is only connected with the steel pipe by locking, so the transverse constraint of the pipe is weak in the construction process. It mainly depends on the longitudinal strength of concrete-filled steel tube structure in pipe curtain and the temporary support structure to form "scaffolding" support system. For this reason, the pipe curtain structure must be accompanied by a dense steel supporting system during excavation, and strictly control the step of excavation. In order to ensure that the bearing capacity and deformation of the pipe curtain meet the requirements. Tedious temporary support structure and complex mechanical system transformation will bring a lot of inconvenience to the construction process. STS pipe curtain structure on the basis of the traditional pipe curtain use of high strength bolts and. The flange plate connects the adjacent steel tubes as a whole, The lateral bearing capacity is improved significantly, and the complicated temporary support can be reduced in the construction process. Based on the engineering background of ultra-shallow buried STS tube screen underground excavating station, taking the STS pipe curtain structure as the research object, the model test is adopted. Numerical simulation and theoretical analysis are used to study the mechanism of STS pipe curtain structure during construction and the failure mode and mechanical properties of STS pipe curtain members. The main results are as follows: under the action of symmetrical concentrated load. Mechanical performance Test of STS Tube Curtain member, The working mechanism and failure mode of STS pipe curtain members are studied. The steel pipe spacing, flange plate thickness, transverse connection mode, concrete strength grade and bolt spacing are discussed. The influence of the key parameters such as uniform load on the bearing capacity of the STS tube curtain member shows that the lower flange plate welding has the most significant influence on the STS pipe curtain bearing capacity, while the steel tube spacing and the thickness of the flange plate have a certain influence on the bearing capacity of the STS tube curtain member. The effects of welding of upper flange plate, strength grade of concrete and bolt length on mechanical properties of STS tube curtain members are small. The mechanical properties of STS tube curtain members under single point concentrated load are tested. The failure mode and working mechanism of STS tube curtain members under concentrated load are studied, and the thickness of flange plate in different transverse connection modes is discussed. The influence of concrete strength grade on the ultimate bearing capacity and stiffness of STS tube curtain member. The results show that the bending failure of STS tube curtain member occurs under concentrated load, and the welding of lower flange plate has the most significant effect on its bearing capacity. The strength of concrete and welding of upper flange plate have little effect on the bearing capacity of STS tube curtain, but the ductility of the member is improved when the strength of concrete decreases. According to the stress characteristics and failure mode of STS tube curtain members, the calculation formula of ultimate bearing capacity of STS tube curtain members under different transverse connection modes is determined. The calculated results of the theoretical formula agree well with the experimental results. According to the stress and failure characteristics of the STS tube curtain members, the calculation model of the STS tube curtain members is established by using the ABAQUS finite element program, the working mechanism is studied, and the thickness of the flange plate and the wall thickness of the steel tube are studied. The influence of concrete content between pipes on STS tube curtain members is analyzed. The STS tube curtain members with different flange plate thickness and steel tube wall thickness are calculated. It is found that the ratio of flange plate thickness to steel tube wall thickness is too large or too small to affect the failure form of STS tube curtain specimen. It is concluded that the ratio of the two factors is reasonable between 1.0-1.3, and the steel tube and flange plate can yield simultaneously. The ductility of STS tube curtain members can be improved by giving full play to their material properties. When the ratio of the two is less than 1.0, only flange plates can reach yield strength, while when the value is greater than 1.3, only the steel pipe reaches yield strength.
【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU93

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