软弱围岩与预筑拱支护相互作用机理研究

发布时间：2018-05-24 16:04

本文选题：软弱围岩 + 新意法　；参考：《北京交通大学》2014年硕士论文

【摘要】：摘要：软弱围岩地质条件下的隧道施工,是隧道工程界面临的重要难题之一。软弱围岩具有变形大、变形速度快、变形难以控制等特点,由于隧道施工中对软弱围岩隧道的变形机理、发展演化规律等认识不足,采取的控制技术与方法缺乏针对性,软弱围岩的隧道开挖面临诸多困难。岩土控制变形分析法为解决软弱围岩隧道施工中的变形控制提供了新的思路,本文根据岩土变形分析法(即新意法)的指导思想,在国家自然科学基金项目“含水弱胶结砂岩隧道预筑拱荷载特性及开挖面稳定性研究(NO.51178026)”的支持下,对机械预切槽技术施作形成的预筑拱支护特性进行了详细深入的研究,通过ANSYS有限元计算、FLAC3D数值模拟、理论解析等手段,研究了预筑拱的合理支护参数、预筑拱控制软弱围岩变形的机理及特性、预筑拱与软弱围岩的相互作用关系及支护特性,主要工作及结论如下： 1、针对预筑拱的合理支护参数,本文根据荷载—结构模型,基于安全系数法,分析研究了不同预筑拱厚度、不同钢拱架支撑间隔距离以及不同混凝土强度条件下预筑拱安全系数的变化情况,为预筑拱支护参数的合理选取提供了支持； 2、基于对拱效应的数值计算,通过FLAC3D三维数值分析,采用地层结构法,根据地层变形曲线、拱顶上方地层压力-深度曲线、拱顶上方压力拱发展及分布形式,分析了预筑拱控制预收敛变形、围岩收敛变形、应力释放等的特点,计算出预筑拱作用下隧道开挖过程中拱顶上方坍落拱发展过程及分布情况,得到了预筑拱控制软弱围岩的变形机理； 3、针对预筑拱控制软弱围岩的变形特性,通过FLAC3D进行大量的数值分析,得出了不同埋深、不同围岩条件、不同预筑拱厚度、不同隧道直径、不同预筑拱支护长度等条件下,预筑拱对于围岩变形、应力释放及重分布过程、拱顶上方坍落拱的发展过程等的控制效果；通过引入拱顶上方地层压力归一化比值λ,得到了隧道开挖过程中拱顶上方地层压力的释放及重分布情况；最终得出了预筑拱控制围岩变形的特性； 4、根据收敛-约束法,基于弹塑性力学有关知识,得出了弹性及弹塑性条件下围岩收敛曲线(围岩特征曲线),在此基础上求出了预筑拱支护下的围岩收敛曲线；在考虑隧道开挖过程中掌子面附近三维空间效应的基础上,引入围岩应力释放系数,得出了掌子面掘进过程中预筑拱与围岩的相互作用关系,求出了预筑拱与围岩相互作用荷载,并基于安全性得出了预筑拱混凝土强度与适用埋深的关系,预筑拱适用埋深随围岩参数的变化规律,为预筑拱支护设计理论的建立奠定基础。
[Abstract]:Abstract : The tunnel construction under the geological condition of weak surrounding rock is one of the most important problems in tunnel engineering .

1 . According to the reasonable supporting parameters of pre - built arch , this paper analyzes the changes of pre - built arch safety coefficient under different pre - built arch thickness , different steel arch support spacing distance and different concrete strength under the load - structure model , and provides support for the reasonable selection of pre - built arch support parameters ;

2 . Based on the numerical calculation of arch effect , through FLAC3D numerical analysis , the characteristics of pre - convergence deformation , convergence deformation of surrounding rock , stress release and so on are analyzed according to the formation deformation curve , the formation pressure - depth curve above the arch top , the pressure arch above the dome roof and the distribution form , and the deformation mechanism of the pre - arch control weak surrounding rock is obtained .

3 . According to the deformation characteristics of the weak surrounding rock controlled by the pre - built arch , a lot of numerical analysis is carried out through FLAC3D , and the control effect of the pre - built arch on the deformation of surrounding rock , the stress release and the redistribution process , the development process of the collapse arch above the arch top are obtained under the condition of different burial depth , different surrounding rock conditions , different pre - built arch thickness , different tunnel diameter and different pre - arch support length .
By introducing the normalized ratio 位 of the formation pressure above the dome roof , the release and redistribution of the formation pressure above the arch top during tunnel excavation are obtained .
Finally , the characteristics of the deformation of the surrounding rock of the pre - built arch are obtained .

4 . According to the convergence - constraint method , based on the relevant knowledge of elastic - plastic mechanics , the convergence curve of surrounding rock under elastic and elastic - plastic conditions is obtained ( the characteristic curve of surrounding rock ) , and the convergence curve of surrounding rock under pre - arch support is obtained .
Based on the three - dimensional space effect in the tunnel excavation process , the stress release coefficient of surrounding rock is introduced , the interaction between the pre - built arch and the surrounding rock is obtained through the interaction between the pre - built arch and the surrounding rock , and the relationship between the pre - built arch and the surrounding rock is obtained . Based on the safety , the relationship between the pre - built arch concrete strength and the applicable burial depth is obtained .
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2;U455.49

【参考文献】