【作者】 李宇杰；

【导师】 何平；

【作者基本信息】 北京交通大学 ， 地下工程， 2012， 博士

【摘要】 由于我国城市用地紧张以及城市立体化交通的要求,地下空间的开发与利用成为现代化城市的首要任务。同时,高度效率化和功能密集化的现代化城市对于工程施工精度的要求也越来越高。盾构法由于其对周围环境影响小、施工自动化程度高等优点,成为城市地下工程建设的主要施工方法。因此,开展盾构隧道设计方面的研究具有重要的学术价值和使用价值,可以为安全、合理、经济的管片设计工作提供指导。作为盾构隧道的永久支护结构,盾构衬砌为整个盾构隧道的关键部位与设计重点。目前,常用的盾构衬砌设计方法最大的区别在于管片接头的假设不同。由于接头形式不同,接头参数的选取对模型计算结果的影响很大。在盾构衬砌的常用设计方法中,均将钢筋混凝土管片假设为弹性体。然而混凝土材料在拉应力和压应力作用下会表现出迥异的强度与刚度特性,尤其是当混凝土材料所受拉应力超过其抗拉强度设计值时,混凝土在受拉应力区会出现微裂缝。因此盾构衬砌的设计模型中应考虑混凝土的材料特性。盾构隧道施工阶段中,受拼装过程、注浆压力、千斤顶推力以及隧道纵向差异沉降等众多施工因素的综合影响,管片结构表现出异常复杂的力学性能。如何合理有效地评价盾构隧道施工阶段对衬砌管片力学性能的影响仍然是衬砌设计和施工中所需要面临的难题之一。本文的主要研究如下：1、在分析盾构隧道衬砌常用设计方法的基础上,采用有限元软件建立了一种可以精确模拟螺栓与管片间相互作用关系的盾构隧道衬砌非连续接触计算模型,并详细介绍了非线性接触问题的计算原理。2、为了验证本文所建立的非连续接触模型的合理性,通过现场原位试验与数值模拟计算相结合的手段对盾构衬砌的受力与变形情况进行研究。详细介绍了原位实验的内容与测试结果,并依据内、外侧钢筋及受压区混凝土的应变协调关系,截面上力与力矩平衡关系,推导得出管片截面的内力计算公式。3、采用荷载。结构模型计算方法,研究了盾构管片在非连续接触模型方法、弹塑性损伤模型方法和惯用法模型方法中的受力与变形特性,得出了管片混凝土材料在拉应力和压应力作用下的强度与刚度特性,由于结构损伤产生的微裂缝特征和三种模型的异同点等。4、采用地层-结构模型计算方法,使用非连续接触计算模型研究了施工过程中螺栓及时拧紧度、衬砌背后注浆不均匀及管片纵缝错台等对盾构管片的影响。并将计算结果与现场实验结果进行了对比分析,归纳得出了各种不规则施工操作引起的盾构管片受力与变形规律。更多还原

【Abstract】 Because of the limitation of city land in our country and the requirement of the three-dimensional city traffic, the development and utilization of underground space has been the primary task in modern city. Meanwhile, high efficiency and dense function of modern city require more precision during engineering construction. Shield method has become the main construction method in urban underground engineering, which has little influence on the surrounding environment and high automation in construction. So the study for the design of shield lining is very valuable for academy and application, which has some guidance for designing shield segment in the aspects of security, rationality and economy.The permanent supporting structure in shield tunnel is shield lining, which is the key part and the focal design point in whole shield tunnel. Now, the biggest difference between common design methods of shield lining is different assumptions on segment joint. Because the joint has different forms, the selection of joint parameters has an enormous effect on calculation results. The common design methods of shield lining all assume the reinforced concrete segments as elastic body. But the concrete material has different strength and rigidity characters under the compressive and tensile stress. Especially, when the tensile stress of concrete is larger than the design value, there will be micro-cracks on the area of tensile stress. So the design model of shield lining must consider the concrete material characters. During the shield tunnel construction process, segment structure show exceptionally complex mechanical property, which influence by construction factors such as assembly process, grouting pressure, jack forces and tunnel longitudinal discrepancy settlement. How to reasonably and effectively assess the influence of mechanical properties of lining segment by shield tunnel construction process still is one of the difficult problems in lining design work and construction. The main research as follows:1. On the base of analysis on the common design methods of shield tunnel lining, a new discontinuous contact computational model of shield tunnel lining is built, which use by finite element software and can accurate simulate the interrelationships between bolts and segments. And it gives a detailed presentation of the calculation principle of nonlinear contact problem.2. In order to verify the rationality of the discontinuous contact computational model, using field test and numerical simulation calculation method to research the force and deformation of shield lining. It gives a detailed presentation of the contents and results of field test. And the calculation equation of internal force is derived, which based on the harmonious relation between the inner side rebar strain, the external side rebar strain and pressure area concrete strain, and equilibrium relation of force and bending moment on section.3. Using load-structure calculation method, study the force and deformation characters of shield segment in discontinuous contact computational model method, elastoplastic-damage model method and routine method model. It obtains the strength and rigidity characters of concrete material under the compressive and tensile stress, the micro-cracks caused by structure damage, the similar and dissimilar characteristics between3models.4. Using soil-structure calculation method and discontinuous contact computational model, study the influence of shield segment by tighten degree of bolts, non-uniform grouting behind lining, and existing dislocation on longitudinal joint. Through simulated results and measured datas, it can draw same conclusions of stress and deformation law of shield segment caused by every irregular construction operation.更多还原