砂性地层土压平衡盾构刀具磨损试验研究

发布时间：2019-06-28 16:35

【摘要】：随着城市轨道交通建设的大规模发展,土压平衡盾构工法凭借自身的优越性在城市地铁隧道施工中扮演着越来越重要的角色。长期以来,盾构刀具的快速磨耗成为制约盾构长距离、快速、连续掘进的重要难题。特别是在砂性地层中石英等磨蚀性矿物含量高,导致刀具严重磨损,容易引起刀盘扭矩过大、掘进效率低下,甚至造成无法继续掘进而被迫开舱换刀。研究砂性地层条件下盾构刀具的切削工作机理和失效模式,获得砂性土磨蚀特性主控因素下的影响规律,提出盾构刀具减磨防护措施,对于延长盾构刀具有效服役期限,保障盾构刀具长距离、快速、安全掘进意义重大。本文以盾构施工中应用广泛、数量众多、易于磨耗的切刀为研究对象,对其运动特性、切削工作机理及失效模式进行详细分析,对影响刀具磨损的诸多因素进行了归纳。针对常见的砂性土体地层,探究颗粒级配、含水率、矿物组分等对砂性土体磨蚀性的影响,并通过正交试验分析施工参数,研究盾构刀具减磨及安全防护措施。主要工作总结如下:(1)分析了盾构切刀的轴向、周向及切深等运动特性,揭示了盾构切刀的工作机理和失效模式,指出盾构刀具在砂性地层中以磨粒磨损为主。通过ANSYS有限元软件对石英等硬质磨粒压入刀具表面并在金属材料表层滑动的过程进行仿真模拟,分析表层金属材料变形过程中的应力应变特性,研究磨粒与刀具微观接触力学关系。(2)开展土体磨蚀性试验,分析砂性土体颗粒级配、含水率及矿物组分对其磨蚀特性的影响。磨蚀系数与砂性土细粒含量、限制粒径具有很好的指数相关性,随含水率先增大后减小,并在砂土最优含水率附近达到峰值,与矿物组分的平均Rosiwal硬度值呈线性相关性。(3)依据实际工程背景选择因素水平,对盾构刀具磨损量产生影响的关键施工参数土舱压力、转速、泡沫注入比进行正交试验。试验数据的分析结果显示在选定的几个参数中土舱压力对磨损量的影响最大,其次是转速,最后是泡沫注入比。根据实验结果,提出了控制推力、调整转速、协调压力、配合改良的多施工参数联动控制的盾构刀具减磨措施。
[Abstract]:With the large-scale development of urban rail transit construction, the earth pressure balance shield method plays a more and more important role in the construction of urban subway tunnel because of its own advantages. For a long time, the fast wear of shield cutting tools has become an important problem that restricts the long distance, fast and continuous excavation of shield machines. Especially in sand formation, quartz and other erosive minerals are high, which leads to serious wear of cutting tools, easy to cause excessive torque of cutter head, low efficiency of excavation, and even unable to continue digging and forced to open the cabin to change knives. This paper studies the cutting mechanism and failure mode of shield tools under the condition of sand formation, obtains the influence law under the main control factors of sand soil erosion characteristics, and puts forward the protective measures for reducing the wear of shield tools, which is of great significance for prolonging the effective service period of shield tools, ensuring the long distance, fast and safe driving of shield tools. In this paper, the cutter, which is widely used in shield construction and is easy to wear, is taken as the research object, its motion characteristics, cutting mechanism and failure mode are analyzed in detail, and many factors affecting tool wear are summarized. Aiming at the common sand soil strata, the effects of particle gradation, water content and mineral composition on the wear and corrosion of sand soil are investigated, and the construction parameters are analyzed by orthogonal test to study the wear reduction and safety protection measures of shield cutting tools. The main work is summarized as follows: (1) the axial, circumferential and deep motion characteristics of shield cutter are analyzed, the working mechanism and failure mode of shield cutter are revealed, and it is pointed out that abrasive wear is the main tool in sand formation. The process of hard abrasive particles such as quartz pressing into the surface of the tool and sliding on the surface of the metal material is simulated by ANSYS finite element software. The stress and strain characteristics of the surface metal material during deformation are analyzed, and the relationship between the abrasive particles and the micro-contact mechanics of the tool is studied. (2) the soil erosion test is carried out to analyze the effects of sand soil particle size, moisture content and mineral components on its wear characteristics. The erosion coefficient has a good exponential correlation with the fine particle content of sandy soil, and decreases with the increase of water cut, and reaches the peak near the optimal moisture content of sandy soil, which is linearly correlated with the average Rosiwal hardness of mineral components. (3) according to the level of selected factors in the actual engineering background, the orthogonal test is carried out on the key construction parameters, such as soil cabin pressure, rotating speed and foam injection ratio, which affect the wear of shield cutting tools. The analysis results of the test data show that the soil cabin pressure has the greatest influence on the wear rate among the selected parameters, followed by the rotating speed, and finally the foam injection ratio. According to the experimental results, the measures to control the thrust, adjust the rotating speed, coordinate the pressure and cooperate with the improved multi-construction parameter linkage control are put forward to reduce the wear of shield cutting tools.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.43

【相似文献】