盾构直接掘削大直径钢筋混凝土群桩研究

发布时间：2018-03-04 22:29

本文选题：盾构　切入点：直接切削　出处：《北京交通大学》2014年博士论文　论文类型：学位论文

【摘要】：摘要：盾构掘进遭遇障碍物桩基时,直接切桩相比于传统方法,影响周边环境小、成本低、工期短,社会及经济效益显著,但目前切桩理论研究与实施技术在国际范围内尚远未成熟,尤其是对于切削大直径桩基。本文依托苏州地铁盾构切削14根中1000～1200mm桥梁桩基工程,综合采用调研、理论分析、有限元仿真、现场试验和工程实测等研究手段,对盾构直接掘削大直径钢筋混凝土群桩的相关机理、理论与技术进行研究。主要研究内容和成果如下： (1)综合考虑材料非线性、几何非线性以及接触非线性,以国际大型非线性显式动力软件为分析平台,对刀刃切削钢筋、混凝土的切削过程、相互作用及细观切削机理进行了研究。 (2)切削钢筋混凝土桩基应选用负前角、双面刃的刀具；通过有限元仿真获得了刀刃前角、刃角、刃宽等对切筋、切砼的影响规律,并以适应连续切削大直径桩基为目标,研发出了新型切桩专用刀具；通过建立三维切削钢筋热力耦合模型和三维切削混凝土全过程模型,揭示了新型刀具的动态切削过程及切削性能；结合仿真计算结果并对比各种磨损类型的发生条件,指出刀具合金切削钢筋、混凝土对应的磨损机理为硬质点磨粒磨损。 (3)从理论上对切桩刀盘刀具配置进行了深入研究：刀具布置形式可采用同心圆法,相邻刀具宜以等相位角差值进行定位,切削轨迹的间距确定应以能实现全覆盖面切削混凝土为原则；考虑掘削桩基对刀盘刀具的多功能需求,提出了包括有正面大贝壳刀、边缘大贝壳刀、中心小贝壳刀、仿形贝壳刀以及羊角储备刀在内的刀盘群刀综合配置方案。 (4)通过建立刀盘切桩数学模型,编制刀盘受力计算程序,获得了推力扭矩与刀盘不平衡力的变化特征,以及桩基尺寸大小、偏移距离对刀盘受力的影响规律,并给出了相应的主动掘削参数设置建议；采用国际大型机械设计软件建立了切桩刀盘刀具模型,并针对最不利的切削工况,对刀盘刚度进行检算并提出了加固措施。 (5)开展了国内外首次的盾构直接切削钢筋混凝土桩基现场试验,分析了切桩效果、刀具损伤规律以及掘削参数特征等,对刀具配置和掘削参数初步方案的合理性进行了验证,并根据试验结果提出了超前贝壳刀的优化配置方案及分次切筋的切削理念,其切削效果得到了群刀切削仿真实验的证实,并最终在工程实践中得到成功应用。 (6)以苏州地铁盾构切削14根大直径桥梁群桩工程为依托,探讨了切桩条件下的上部结构与管片衬砌的安全性能；从刀盘刀具、螺旋输送机、小流量推进泵、外包管等多方面研究提出了盾构综合改造加强方案；形成了以“慢推速、中转速、保土压、注惰浆、控姿态”为核心的盾构掘削大直径桩基施工控制技术。
[Abstract]:Absrtact: when shield tunneling encounters obstacle pile foundation, compared with traditional method, direct cutting pile has less influence on surrounding environment, lower cost, shorter time limit, and remarkable social and economic benefits. However, at present, the theoretical research and implementation technology of cutting pile is far from mature in international scope, especially for cutting large diameter pile foundation. In this paper, based on the Suzhou Metro Shield Machining 14 piles of 1000 ~ 1200mm bridge foundation engineering, the comprehensive use of research, theoretical analysis, By means of finite element simulation, field test and engineering measurement, this paper studies the mechanism, theory and technology of direct excavation of large diameter reinforced concrete pile groups by shield tunneling. The main contents and results are as follows:. 1) considering the material nonlinearity, geometric nonlinearity and contact nonlinearity, the cutting process of steel bar and concrete on the cutting edge of steel bar and concrete is analyzed on the platform of international large-scale nonlinear explicit dynamic software. Interaction and micro-cutting mechanism were studied. (2) cutting reinforced concrete pile foundation should use the tool with negative front angle and double edge, and through finite element simulation, the influence law of the cutting edge angle, edge angle, edge width etc. on the cutting of reinforcement and concrete is obtained, and the aim is to adapt to the continuous cutting of large diameter pile foundation. A new type of special cutting tool for pile cutting is developed and the dynamic cutting process and cutting performance of the new cutting tool are revealed by establishing a three-dimensional coupled model of cutting steel bar and the whole process model of three-dimensional cutting concrete. In combination with the simulation results and the comparison of the occurrence conditions of various wear types, it is pointed out that the wear mechanism of tool alloy cutting steel bar and concrete is hard spot abrasive wear. 3) the tool configuration of cutting pile cutter head is studied in theory: the tool arrangement can adopt concentric circle method, and the adjacent tool should be located by equal phase angle difference. The spacing of cutting track should be determined according to the principle that the cutting concrete can be fully covered. Considering the multi-function requirement of cutting tool for cutting pile foundation, it is proposed that there are large shell knife with frontal surface, big shell knife with edge, small shell knife in center. The integrated configuration scheme of knife head group knife including copying shell knife and goat horn reserve knife. 4) by establishing the mathematical model of cutting pile of cutter head and compiling the calculation program of force on cutter head, the variation characteristics of thrust torque and unbalanced force of cutter head, the influence of pile foundation size and offset distance on the force of cutter head are obtained. The paper also gives the corresponding suggestions for setting the cutting parameters of active driving, establishes the cutting tool model of the cutting pile cutter by using the international large-scale mechanical design software, and checks the stiffness of the cutter head and puts forward the reinforcement measures in view of the most unfavorable cutting conditions. In this paper, the first direct cutting test of reinforced concrete pile foundation is carried out at home and abroad, and the effect of cutting pile, the law of tool damage and the characteristics of cutting parameters are analyzed. The rationality of tool configuration and initial scheme of cutting parameters is verified. According to the experimental results, the optimal configuration scheme of the advanced shell cutter and the cutting idea of the graded cutting rib are put forward. The cutting effect is verified by the simulation experiment of the group cutter cutting, and finally it is successfully applied in the engineering practice. The safety performance of the upper structure and segment lining under the condition of pile cutting is discussed based on 14 large diameter bridge group piles cutting by shield tunneling in Suzhou Metro, and the safety performance of the upper structure and segment lining under the condition of cutting pile is discussed, which includes cutter cutters, screw conveyors, small flow propulsive pumps, etc. In this paper, the comprehensive reconstruction scheme of shield tunneling is put forward, and the construction control technology of shield tunneling large diameter pile foundation with the core of "slow pushing speed, medium speed, retaining earth pressure, inert slurry injection and attitude control" is formed.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U455.43;U455.39

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