盾构泡沫发生系统设计毕业论文.doc

盾构泡沫发生系统设计毕业论文盾构泡沫发生系统设计毕业论文 目录 第 1 章 绪 论 1 1 1 盾构机的发展历史 1 1 2 我国盾构技术的应用现状及发展趋势 2 1 2 1 应用现状 2 1 2 2 发展趋势 3 1 3 盾构技术的工作原理及其特点 4 1 3 1 盾构技术基本概念 4 1 3 2 盾构技术基本原理 4 1 3 3 盾构技术施工的基本特点 4 1 4 研究内容 5 1 5 本章小结 5 第 2 章 泡沫系统原理及施工控制 6 2 1 泡沫系统简介 6 2 2 泡沫注入工法 6 2 2 1 泡沫注入法工法的特点 6 2 2 2 适用范围和使用材料 7 2 2 3 泡沫改良土体的机理研究 8 2 2 4 适合使用泡沫改良的地层 9 2 3 泡沫加注系统 10 2 3 1 泡沫加注系统的组成 10 2 3 2 泡沫系统工作原理 10 2 4 本章小结 13 第 3 章 参数计算及选型 14 3 1 泡沫系统参数的计算 14 3 2 硬件的选型 16 3 2 1 泡沫剂泵的选择 16 3 2 2 水泵的选择 18 3 2 3 空压机的选择 19 3 2 4 管路的选择 19 3 2 5 各支路的阀 管接头 传感器及指示仪表等的选择 20 3 3 泡沫发生器的设计 23 3 3 1 泡沫发生特性 23 3 3 2 泡沫发生器主参数的确定 24 3 4 本章小结 27 第 4 章 盾构发展与展望 28 4 1 结论 28 4 2 展望 28 4 2 1 盾构的发展方向 28 4 2 2 我国盾构市场前景 29 4 3 本章小结 30 参考文献 31 致 谢 32 附录 外文翻译 33 石家庄铁道大学毕业设计 1 第 1 章 绪 论 1 1 盾构机的发展历史 1818年Marc Isambard Brunel获得隧道盾构法施工的专利 并在1825年到1843年 间首次使用盾构在伦敦的泰晤士河下修建了一条河底隧道 初步证明盾构法隧道施 工的价值 1830年由劳德考克让施 Lord Cochrance 发明了施加压缩空气防止涌水 的 气压法 1874年格雷蒙特 James Henry Greathead 在伦敦地铁南线的隧道建设 中采用了气压盾构法的施工工艺 并首创了在盾尾后面的衬砌外围环形空隙中压浆 的施工方法 并开发了用流体支撑开挖面的盾构 开挖出的弃土以泥水流的方式排 出 1896年Haag在柏林第一次申请了德国泥水式盾构的专利 形成了现代泥水式盾 构的雏形 推动了盾构施工技术的发展 到20世纪初 盾构施工法在英 美 德 俄 法 日等国开始推广 1917年日本开始在铁羽越线的折返段隧道施工中引进盾 构法 1938年正式在国铁关门隧道应用盾构法施工 为日本盾构技术的发展奠定了 基础 1967年由英国提出的泥水加压系统在日本得到了实施 日本研制成功第一台 有切削刀盘 水力出土的泥水加压式盾构 直径为3 1m 1974年日本独创性地研制 成功土压平衡盾构 同时德国Wayss lts analysis show that the foam helps to improve the machine drilling performances in sands but its usefulness with aggrega es is limited 1998 Published by Elsevier Science Ltd All rights reserved 1 Introduction The realization of underground works in soft and water bearing grounds and the increasing concern with the envirc nment seems to favor the use of earth pressure balanced EPB shields In order to expand the fieldof use ofthis technology which was originally designed for use in cohesive soils with low plasticity some research has led to the development of additives products including chemical foam Nishitake et al 1993 Reda 1994 Ishimoto et al 1995 Despite the success of the EPB shield some questions remain about this technology as evidenced by the recent launching of two French research projects Eupalinos 2000 and Microtunnels Experimentation on a microtunneling site using foam injection in 1992 pointed out the necessity for the tests to be continued Quebaud 1992 First a methodology ofresearch ofthe best products able to respond to the working requirements of a machine in a given soil was defined It was then divided into three steps FSTT 1993 石家庄铁道大学毕业设计 34 Abbreviation Explanation of Terms AbbreviationExplanation of Terms Ka expansion ratio of foam mesured under the atmospheric pressure K expansion ratio of foam mesured under a defined pressure Paatmospheric pressure MPa Pdefined pressure earth pressure MPa Pgmgeneration pressure of foam MPa Tifoam injection ratio Coam consumption of foaming agent g m3 of excavated soil Kpermeability of the foamed soil m s Camconcentration of foaming agent Gp power reduction mixing test Wwater content of the soil S1fine siliceous sand S2siliceous sand G1siliceous aggregate SG1aggregate mixture of 2 and G1 Tensio1foaming agent Tensio2foaming agent 1 the study of the products used for the foam generation as well as the foam characteristics 2 the preparation ofspecifications ofthe characteristics required by the excavated soil in order to optimize the working of an EPB shield 3 the design of simple tests for the foam characterization but above all for the study of the foamed soil A laboratory tests campaign was then carried out with typical soils in order to study the different problems which occur during the excavation the research campaign results are given hereafter Quebaud 1996 2 The Foam Study 石家庄铁道大学毕业设计 35 Although the industrial applications offoam are various its use in underground works has been concentrated in two fields cellular concrete and drilling operations Venuat 1984 Myers 1992 The chemical products used to produce foam are called surfactants or surface active agents These products have the distinctive characteristic of modifying the solution air interactions when they are in water Marcou 1990 The foam can be defined as a physical state in which a gaseous phase is dispersed in bubble form in a second liquid phase The main parameters describing a foam are foaming ability that is the amount offoam produced with a certain quantity of liquid under some known conditions persistence which is its capacity to maintain a con stant volume and keep the liquid of the matrix from flowing out the degree of foam dispersion mainly characterized by the average bubble size Another parameter is quite important for the foams produced industrially their expansion ratio K equal to the volume of foam produced divided by the initial volume of liquid A number of factors can influence the foam characteristics such as the surfactant concentration and the use of admixtures which act on foam ability and persistence foaming or antifoaming products The compressibility of foam is important too because the foam is injected in a confined middle earth pressure it is necessary to know its behaviour under pressure With K the expansion ratio a measured under the atmospheric pressure P we can write that for a pressure P 1 1 a a a K p P K 3 Action of Foam on Excavated Soil The soil excavated by an EPB shield must have some characteristics which optimize the machine s operation Depending on the nature of the soil it may be necessary to mix it with some foam in order to modify its original characteristics At the beginning this shield was used in soft grounds like silts or soft clays with a satisfactory water content Other types of soil present different problems e g sticking and plugging for hard clays lack of plastic fluidity and high permeability for granular soils The paste obtained by the mixing of excavated soil and foam must be close to the plastic state called the pseudofluid or pseudo plastic state must be impermeable and must not stick or even plug To reach a plastic state means that the foam brings the water content ofthe excavated soil to an optimal value In addition because the main function of a closed front shield is the stabilization of the face it is necessary to control the confining pressure which must be close to the insitu pressure The muck in the chamber should then be homogeneous allowing its continuous removal The air bubbles ofthe foam 石家庄铁道大学毕业设计 36 also allow the reduction of the pressure variations in the chamber For granular soils it is necessary to limit water ingress at the face the presence of foam in front of the cutter head allows soil impregnation producing a cake expression used for the slurry shield Finally the foam has lubricating properties the muck removal from the face to the end of the excavation screw is easier These properties also help to reduce abrasion of the different parts of the shield Table 1summarizes the main parameters over which the foam must act in order to optimize the excavation 4 Test Laboratory The next step was to design a test laboratory in order to characterize the products able to respond to the needs of the laboratory and to study the foam produced with an industrial generation bench However the main purpose of these tests was to study the behaviour of different foamed soils 4 1 Characterization of the Foam In order to characterize the foam used with an EPB shield it was necessary to consider the surfactants able to produce foam the equipment for its generation and the characterization tests The laboratory was equipped with an industrial genera tion bench whose operation is the same as the equipment present on the machines using foam injection see Fig 1 This automatic foam generator bench is installed on anautonomous truck and contains an air compressor an airflow meter a tank of l oaming agent and its pump a waterpump and an automaton which regulates the different flowrates and gives some information about the generation It can be used in two different operating modes autonomous and non autonomous for laboratory tests and site use respectively In these two modes we can choose the concentration of foaming agent in water between 1 and 5 and the expansion ratio between 6 and 30 If the flow rate is defined by the user fi r the 石家庄铁道大学毕业设计 37 autonomous mode between 1 and 15 m3 h it is automatically determined in the other mode some machine parameters are taken into account diameter advancing speed pressure in the chamber If an admixture is used it is incorporated in the water inlet Some simple tests of foam characterization were chosen the generation test to study the generation pressure APg provoked by the fluid passage in the generator in relation with the foam flow rate the consistency test to quantify the foam quality with a parameter independent of any generation system the half life test to measure the time necessary for a foam volume equal to 251 to lose half of the solution which was used for its generation and the compressiibility test to understand the foam behaviour in a confined environment and with pressure variations between 0 1 and 0 4 MPa Table 1 Foam influence on the working of an EPB shield ParameterFoam influence soil consistency To give to the soil a pseudo hydraulic state that is to say able to transmit pressures To give to the soil a pseudoplastic state able to create a pressure gradient along the extraction screw ground permeability To make the excavated soil almost impermeable Homogeneity To make the mixing between soil and foam easier in order to obtain a paste with the required qualities sticking compaction fine soils To avoid the colmation of muck due to the sticking of the clay To avoid an overconsolidation of the fine elements under the mechanical action of the cutting head and the screw friction To help the muck circulation from its excavation to its storage 石家庄铁道大学毕业设计 38 To reduce the abrasive behaviour of some soils confining regulation To help the muck circulation from its excavation to its storage To reduce the abrasive behaviour of some soils impregnation granular soils To give an apparent cohesion to the soil at the head front through its impregnation in a limited depth 4 2 Characterization of the Foamed Soil Because the purpose of the laboratory was to study the foam influence in relation to the parameters described in Table 1 different te 3ts were perfected Special attention was given to the choice of the equipment and to the establishment of operating procedures All the tests were performed on a foamed soil characterized by the foam injection ratio T equal to the volume of injected foam dividect by the volume of tested soil It was then possible to calculate the consumption Coam of foaming agent in g per m 3 of excavated soil 4 2 1 The mixing test In order to study the mixing between soil and foam it was necessary to use a mixer with a vertical axis see Fig 2 石家庄铁道大学毕业设计 39 During the evolution of the foam injection in the tested soil the variation of the electric motor power the mixing time necessary to obtain a homogeneous mixture and the quality and behaviour of the mixture were observed 4 2 2 The slump test The slump test was chosen to determine the consistency of the foamed soil and to quantify its plastic fluidity because it is quite simple and rapid ISO norm n 4109 A slump value equal to 12 cm is considered to characterize the optimal fluidity this value corresponds to the average value for a plastic concrete 4 2 3 Adhesion test The evolution of adhesion is determined by the measure of the friction angle of the mixture on a sloped plate of stainless steel Although this approach is quite far from the phenomenon of adhesion occuring on the machine it permits estimation of the lubricating foam properties 4 2 4 Permeability test This test is quite important when the machine drills under the water table because the incoming water can provoke a disaster at the face Such a disaster is due to the carrying of fine elements which are in the extraction screw it then becomes difficult to maintain the plastic consistency necessary for the pressure gradient along the screw In order to be sure of the foam s ability to maintain the excavated soil almost impermeable it was decided to measure the permeability k of the mixture with a constant head permeameter see Fig 3 The critical value for permeability varies between 10 5 and 10 m s depending on the authors Briglia et al 1989 Herrenknecht 1994 石家庄铁道大学毕业设计 40 4 2 5 Impregnation test The cake phenomenon associated with the slurry shield has to be compared with the foam injection at the head front the sustaining agent injected with a little overpressure gets into the soil pores expelling water As for the slurry shield the soil impregnation at the front of an EPB shield must have characteristics such that the pressure gradient in the first grains is sufficient to maintain the head front and the impregnated area is not destroyed at each tool s passage The impregnation depth must be limited so that the foam does not run into the ground To model this phenomenon experimentally a confining cell was chosen see Fig 4 This cell is composed by a body made of Plexiglas with an inner diameter equal to 280 mm and a height equal to 800 ram its maximal pressure is 0 5 MPa This body is equipped with inferior and superior aluminium base plates Independent manometers are installed to regulate the pressure at the higher and lower parts of the sample 石家庄铁道大学毕业设计 41 The principle of the impregnation test is to apply a confining pressure to the sample at the higher part and a counterpressure with the water reserve at the lower part Foam is injected at the top of the sample in this confined environment and the impregnation depth of the soil is then evaluated in relation with time Conclusions In concluding this study it can be said that the first part of the testing which consisted of studying the foam characteristics persistence foaming ability compressibility has pointed out the importance of the generation process influence on foam quality and has shown that the use of viscosifying agents requires special attention saturated and granular soils The second part of the tests permitted study of the behaviour of different foamed soils From the results obtained with different foamed sands it can be said that the foam has some positive effects concerning the fluidification and the lubrication of the mixture the ground impregnation and the power reduction 石家庄铁道大学毕业设计 42 土压平衡盾构机掘削粒状土时泡沫的应用 摘要 在用土压平衡盾构法实现地下施工中 泡沫得到广泛应用 并在此施工 法中引起关注 这是最近法国两个工程Eupalinos 2000和Microtunnels的研究 主题 所以Lille的机械实验室决定用科学方式对这种盾构中泡沫的工作进行研 究 研究表明泡沫和开挖土混合后表现的特性可以改善机械的操作 同时设计 了一些研究泡沫土壤混合特性的简单实验并实现了粒状土壤的测试 分析结果 显示泡沫也可以改善盾构机在沙土中的掘削情况 但作用有限 注 版权归Elsevier 科学有限公司所有 1 简介 从泥水为主的地下工程施工和环保两方面来看 土压平衡盾构机的应用似乎 更受青睐 为了拓展此项技术的应用领域 对低塑性的土质来说 需增加一些 装置 如泡沫装置 来改善其性能 尽管EPB盾构性能优越 但技术仍有需改进之处 这点在法国最近两项工 程Eupalinos 2000和Microtunnels得到验证 1992年的微型盾构的泡沫注入实 验也证实此点 首先 在给定的土质下 已定义了满足工程要求的施工方法 可分为三步 1 泡沫发生装置及泡沫特性的研究 2 为利于EPB盾构的作业 开挖土所需泡沫的性能规格的准备 3 针对泡沫特性的简单测试 尤其是土壤泡沫化后的特性的研究 实验室测试以典型土壤为例是为了研究在开挖过程中可能遇到的不同问题 2 泡沫的研究 尽管泡沫在不同的工业领域的应用是不同的 但在地下施工中它的研究集 中在两个方面 化学成分和在掘削过程中的作用 发生泡沫的化学物质叫做表面活性剂 当遇水时三种物质为混合空气发挥 着不同作用 泡沫可以被定义为一种物理状态 在此状态下 气体分散在以液体介质的 泡沫中 描述泡沫的主要参数有 发泡率 即在已知条件下 一定量的液体发出的泡沫数量 石家庄铁道大学毕业设计 43 持续性 指泡沫维持一定体积的能力并使液体持续注入 泡沫分布度 主要靠起泡的平均大小来衡量 其它参数对于工业用起泡性能也很重要 膨胀率K 值等于起始的液体体积 除以泡沫液的体积 一些因素会影响泡沫的性能 如表面活性剂的集中性和混合剂的应用 这 些都会作用在发泡的能力和持续性上 泡沫的压缩性也很重要 因为泡沫是在 常压下注射的 就有必要知道泡沫在施压时的特性 可以用下面的式子来表示 膨胀率和大气压和气压的关系 1 1 a a a K p P K 3 在开挖土壤中泡沫的作用 从EPB盾构中挖出的土壤须有一些特性以配合盾构机的作业 根据土壤的种 类不同 需混合泡沫来改善它最初的特性 起初 盾构用于开挖淤泥或软的泥 土 有较适宜的含水量 而其它土质会引发一些问题 比如硬土会引起堵塞和 排土不畅不良 粒状土质会导致塑流行不良和渗透性高 开挖出的土和泡沫混合物呈浆状 接近塑流状态并且不会渗透 不会引起 黏着和堵塞 要达到塑流状态意味着泡沫使土壤的含水量达到最佳状态 除此之外 开挖仓的主要作用是维持开挖面的稳定 故需要将内部的压力 限定为土压和水压的和 排土仓和前仓的土壤应是均质等压的 并有连续的塑 流性 泡沫的气泡可以缓解开挖仓压力的变化 对粒状土壤 有必要限制水进入开挖面 刀头部的泡沫与使土壤混合使其 饱和 形成 泥饼 用于泥水盾构 最后 泡沫还具有润滑作用 可使土渣更顺利地从开挖面运至螺旋输送机 的后方 这样的作用也可降低盾构其它部件的磨损 表一概括了泡沫促进作业的主要参数 参数的缩写及释义 参数的缩写释义 Ka 标准大气压下泡沫的膨胀率 K 限定气压下泡沫的膨胀率 Pa 气压压力 MPa P 限定压力 土压 MPa Pgm 泡沫的发生压力 MPa Ti 泡沫注入比 石家庄铁道大学毕业设计 44 Coam 泡沫剂注入率 K 注入泡沫后的土壤浸透性 Cam 泡沫剂含量 Gp 能量消耗 混合测试 W 土壤含水量 S1 矽酸细沙 S2 矽酸沙 G1 矽酸骨料 SG1 骨料 S2和G1的聚合 Tensio1 泡沫剂 Tensio2 泡沫剂 4 测试实验 下一步要设计一个测试实验室以描述满足实验需要的产品及泡沫的特 性 然而 这些测试的主要目的是研究不同的泡沫化土壤的特性 4 1泡沫的特性 为了描述EPB盾构用的泡沫 有必要考虑泡沫剂 泡沫发生装置和特性测试实验 多个因素 表一 泡沫影响在EPB盾构上的影响 参数泡沫影响 土质均匀性传递压力 使土壤具有塑性 能够产生沿螺旋输送机方向的分力 土壤渗透性减少土壤渗透性 均质土壤和泡沫更易于混合 获得浆