【作者】 王智猛；

【导师】 蒋关鲁；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2009， 博士

【摘要】 我国西南、西北、中南及东南地区均有广泛的红层分布。红层泥岩作为一种特殊材料,其颗粒易破碎、强度低、遇水后易崩解与软化,表现出与一般填料不同的工程力学性质,使得这些地区的铁路建设面临着优质填料严重缺乏的问题。目前,我国铁路建设处于高速发展期,《国家中长期铁路网规划》也进行了调整,计划到2020年,全国铁路营业里程扩大到12～13万公里,增加了2.9万公里。截止目前,已完成7.5万公里的建设,还差5.4万公里铁路待建,其中相当一部分线路需经过红层地区。如果能使红层材料用于高速铁路路基填筑,则可节省大量工程投资,同时减少大量的弃方,保护环境,具有显著的社会效益与经济效益。但工程界对红层泥岩能否用作高速铁路路基填料存在很大争议。由于对红层泥岩材料工程性质的研究相对缺乏,加上采用不合理的路基结构型式及技术指标,红层泥岩土路堤常常出现沉陷、开裂、边坡垮塌与剥蚀、表层松散、承载力不足等病害。因为高速铁路对路基强度、变形要求很高,路基填料应具有易压实、密度大、强度高、变形小、稳定性和耐久性好、经济等特点,所以有人认为红层材料的水稳定性问题不好解决,建议高速铁路路基不能采用红层材料填筑;有人建议只能采用红层泥岩改良土填筑高速铁路路基。同时也有人从我国铁路低成本建设的国情出发,试图在现有高速铁路路基设计理论的指导下,通过详细研究红层泥岩的工程性质,合理设计与严格施工,扬其长避其短,解决红层泥岩填筑高速铁路路基的适应性与工程技术问题。科研项目“遂渝线无砟轨道线下工程关键技术试验研究”与“达成铁路红层泥岩路基基床动力学特性试验研究”就是在这种背景下立项并开展的。过去针对红层的研究主要集中在红层工程地质、岩体结构特性、岩体力学特性、风化等内容,而有关红层泥岩土路用性能的研究相对较少。近年来,红层泥岩土路用性能研究相继得到开展,主要包括红层泥岩的崩解特性、矿物成分、胶结物质、力学性质、渗透性与压实工艺等,而关于红层泥岩土的动力特性、红层泥岩土用作基床底层填料的研究则属空白。本文结合上述两个科研项目,在详细调研红层泥岩研究现状的基础上,首先通过大量的土工试验详细掌握红层泥岩及其改良土的压实特性、动静力学特性及水稳定特性等,通过对比,找出红层泥岩与常用路基填料的异同点;在高速铁路路基设计理论的指导下并结合国内外经验,对红层泥岩路基进行初步设计;通过路基离心模型试验、路基现场沉降观测、路基现场循环加载试验以及数值计算等手段详细掌握红层泥岩及其改良土路基的动态工作性能、沉降特性、稳定性等,验证并改进红层泥岩路基设计技术;在试验基础上结合已有经验提出系统的红层泥岩土路基的关键设计技术、施工技术与改良工艺等;最终总结出合理使用红层泥岩填筑高速铁路路基的整套技术体系,希望为红层泥岩在高速铁路路基工程中的推广应用提供有力参考。本文的研究内容与结论主要包括如下几个方面:1.通过调研国内外红层泥岩土在铁路、公路领域的应用历史和研究现状,详细总结了红层的成因、分布、矿物组成与化学成分、结构特性、崩解特性、膨胀收缩特性、力学性质、红层泥岩路基病害及产生机理等已有的研究成果。在调研结果的基础上,结合高速铁路路基工程的特点,有针对性、开创性的开展了一系列研究工作。2.针对遂渝线与达成线沿线代表性红层泥岩土样,进行了压实特性、强度变形特性与水稳定特性等物理力学性质的试验研究。结果表明压实红层泥岩土与常用路基填料相比具有密度大、强度高、浸水后有微弱的膨胀性并且软化严重的特点。因此使用红层泥岩填筑路基时应采取一定的措施,充分利用红层泥岩土的高强度、小变形等特性,避开红层泥岩土软化的缺点,扬长避短。3.根据高速铁路基床底层的受力特点,首次采用振动三轴试验对压实红层泥岩土进行了研究,详细掌握了其动强度、临界动应力、累积变形、动模量与阻尼比等动力学特性,为高速铁路红层泥岩路基的动力设计奠定了基础:并根据试验数据建立了红层泥岩土动力累积变形预测模型,为高速铁路红层泥岩路基的动力累积沉降数值计算提供了理论依据。(1)红层泥岩土在25、50kPa围压下的临界动应力分别为150kPa、175kPa;动强度随振次增大而减小,随围压增大而增大:红层泥岩土的动模量随动应变的增大而减小,并且随围压增大而增大:阻尼比随动应变增大而增大,在相同的动应变下,阻尼比随围压增大而减小。现场循环加载试验中红层泥岩基床所受动应力远小于其临界动应力,表明红层泥岩层不会发生强度破坏且变形可趋于稳定。(2)综合考虑密度、含水率、侧向应力、动应力幅值与频率等对红层泥岩土累积变形特性的影响,根据振动三轴试验数据,提出了红层泥岩土的动力累积变形预测模型。根据红层泥岩累积变形预测模型并结合动力学分析计算得到的红层泥岩基床底层(1.7m)的累积沉降为3.94mm。4.在高速铁路路基设计理论的指导下,结合红层泥岩土材料特性,提出了无砟轨道与有砟轨道红层泥岩路基结构型式与设计参数,并通过长期运营或现场循环加载试验证明了其合理性。有砟轨道红层泥岩路基基床结构可为0.6m级配砂砾石(或碎石)+0.2m中粗砂夹复合土工膜+1.7m红层泥岩土,路堤本体由红层泥岩土填筑。对于无砟轨道基床结构,可采用以下标准:①基床总厚度3.0m,其中表层级配碎石0.7m,底层A、B组填料2.3m,下部为红层泥岩路堤本体,适用于板式无砟轨道与轨枕埋入式无砟轨道;②基床总厚度2.7m,其中表层级配碎石0.4m,底层A、B组填料2.3m,下部为红层泥岩路堤本体,或表层级配碎石0.7m,防水层0.2m,下部为红层泥岩路堤本体,适用于双块式无砟轨道。5.首次针对针对达成线“0.6m级配砂砾石(或碎石)+0.2m中粗砂夹复合土工膜+1.7m红层泥岩土”的红层泥岩土基床结构等3种基床结构采用现场循环加载试验方法(ZSS50加载设备),掌握了其在多种工况条件下(不同列车轴重与降雨影响)的动应力、动位移、加速度等动态响应大小与分布,结果表明其动力特性满足时速200km铁路设计要求。试验结果与动力有限元法计算结果吻合良好。(1)ZSS50循环加载设备作为现场循环加载试验的主要设备,经试验验证,可满足不同幅值不同频率的动力要求,可模拟不同轴重不同速度的列车对轨道及路基的动力作用,是研究轨道及路基动力特性的重要设备。(2)红层泥岩土基床的最大动应力、动位移及加速度分别为43.89kPa、0.755mm及6.201m/s~2;红层泥岩基床底层的最大动应力、动位移及加速度分别为20.58kPa、0.529mm及4.166m/s~2;在同一频率下,列车轴重是影响基床动态响应的主要因素,大气降雨的影响有限。6.采用离心模型试验、现场路基沉降观测、现场循环加载试验与数值分析等方法,对红层泥岩土路基的压密沉降进行了分析。红层泥岩土路基在重力作用下的压密沉降由红层泥岩粗颗粒崩解、流变、非饱和土固结以及路基结构侧向变形等多种因素引起。建议采用(压密沉降量占路基高度的)百分率法对红层泥岩土路基压密沉降量进行分析。在目前高速铁路路基设计与施工技术条件下,高速铁路红层泥岩土路基(高度≤6m的有砟与无砟轨道路基)压密沉降的压缩率为0.2‰～0.46‰,红层泥岩改良土路基(高度≤6m的有砟与无砟轨道路基)压密沉降的压缩率为0.12‰～1‰,变形趋于稳定的时间为5个月～7个月;红层泥岩层本身压缩率小于0.67‰,红层泥岩改良土层本身压缩率小于0.65‰。设计时可将路基高度的1‰作为高速铁路红层泥岩土路基压密沉降值,变形趋于稳定的时间为5个月～7个月。7.红层泥岩土路基受大气降雨或浸水作用产生的软化的深度大小直接受红层泥岩土的压实质量的影响。若粗颗粒少、压实密度大、孔隙小,则土体的渗透系数小,大气降雨对路基的影响深度有限,雨水较难进入路基内部,而是仅仅影响路基面与边坡表层。红层泥岩土的膨胀率随荷载的增大而减小,且膨胀率都较小。由于红层泥岩路基设置了防水层并采取了防排水措施,将红层泥岩土体与大气降雨隔离开来,能快速的排除大气降雨,因此可以认为压实红层泥岩土的浸水软化与膨胀特性对高速铁路路基的影响非常有限。8.综合考虑红层泥岩的崩解与软化特性、路基压实质量、施工机械对红层泥岩粗颗粒的进一步破碎作用、工期等因素,确定了填筑路基时红层泥岩填料粒径大小的标准,即崩解或破碎后的最大粒径≤15cm。从红层泥岩土的压实特性、强度特性、路基边坡稳定性、沉降特性等几个方面论证了红层泥岩土的强度变形特性满足高速铁路路基的要求。从红层泥岩土的动强度、动力残余累积变形、红层泥岩基床实际动态响应以及红层泥岩基床结构型式等几个方面论证了红层泥岩土的动力特性满足高速铁路路基基床底层的要求。从红层泥岩土的软化特性、膨胀收缩特性、压实红层泥岩土路基受雨水的影响程度、防排水措施设置等几个方面论证了红层泥岩土的水稳定特性对路基的不利影响非常有限。最终确定红层泥岩土填筑高速铁路路基是适宜的。9.对红层泥岩改良土进行了压实、强度、水稳定性等试验研究,并通过离心模型试验、现场路基沉降观测、现场循环加载试验等方法对改良土路基的工作性能进行了研究。试验结果表明红层泥岩改良土强度高,变形小,遇水不易软化,水稳定性好,可满足高速铁路路基强度、变形、稳定性与耐久性等要求。10.结合红层泥岩本身的材料特性(崩解、软化、膨胀性等)与相关的路基工程设计施工经验,提出了较为系统的高速铁路红层泥岩及其改良土路基设计与施工关键技术,主要包括红层泥岩的选用标准与使用方法、路基结构型式(包括无砟轨道与有砟轨道)、路基边坡加固和防护技术、防排水技术、施工工艺、改良工艺、质量检测标准等,并经过现场试验段的长期检验证明是合理的。红层泥岩及其改良土路基设计与施工技术为红层泥岩在高速铁路路基工程中的推广应用提供有力参考,对红层地区时速200km以上铁路路基设计、施工、管理具有指导意义,具有显著的社会与经济效益。研究成果总体达到国际先进水平。更多还原

【Abstract】 China’s southwest, northwest, southeast and central-south regions have a wide range of distribution of red beds. As a special material, red-mudstone shows different engineering mechanics nature with the general subgrade fillings because it’s intensity is low, and it’s particles are easily soften and collapsed to meet water. So it faces with a serious lack of quality fillings for railway construction in these areas. At present, China’s railway construction is in the development of high-speed, and "state railway network and long-term planning" carrys out some adjustment which plans that in 2020, operating mileage of national railway is to be extended to 130,000 km, with an increase of 29,000 kilometers. Up to now, construction of 75,000 kilometers has been completed, with 54,000 kilometers left to be built, and a considerable number of them will be across the red beds areas. If red-mudstone can be used to fill subgrade in high-speed railway, we can save a lot of projects investment at the same time to reduce a large number of abandoned side, and protect the environment.However, there is a big controversy for the applicability of using red mudstone to fill railway subgrade in engineering field. The relative shortage of engineering properties research for red-mudstone material, and unreasonable use of the subgrade structure and technology indicators make the embankments arise some diseases, such as subsidence, cracking, collapse of the slope, and so on. Because of the high strength and deformation requiments of subgrade for high-speed railway, the fillings should have some characteristics, such as good compaction, big density, high strength, small deformation, stability, durability, economic and so on. So it’s less for red-mudstone to be used as fillings of subgrade in high-standard railway. So some people believe that red-mudstone can’t be used to fill subgrade in high-speed railway because it’s water stability is difficult to be solved. Some people suggest that only improved red-mudstone can be used. At the same time, some people want to attempt to solve the applicability and technology for using red-mudstone to fill subgrade in high-speed railway through detailed study on the characteristics of red-mudstone, reasonable design and strict construction under the guidance of the theory of subgrade design. Under this situation, the scientific research projects, "experiment study on key technology for ballastless track under line project in Suining-Chongqing line" and "experiment study on dynamic performance of red-mudstone subgrade bed in Dazhou-Chengdu line" are carried out.In the past, the research of red-mudstone was mainly focused on engineering geology, rock structure characteristics, rock mechanics properties and weathering, but the road performance of this material was less studied. In recent years, the road performance studies on red-mudstone have emerged one after another, which include the crack properties, mineral composition, cement materials, mechanical properties, permeability and compaction process. The studies on dynamic properties of red-mudstone and being used to fill the subgrade bed are blank. Combined the above two scientific research projects, and based on detailed investigation of present research situation for red-mudstone, the research work is carried out. First, compaction, mechanical and water stability characteristics of red-mudsone are researched. Second, preliminary design of red-mudstone subgrade is made under the guidance of the theory of subgrade design and domestic or overseas experience. Through centrifugal model test, cyclic loading test at the scene, subgrade settlement observation test on-site and numerical analysis, the the dynamic responses, settlement law, and the stability of red-mudstone subgrade are detailedly researched. The results of them are used to prove and improve the design technology for red-mudstone subgrade. Based on the experimental results and experience, the key design technology and construction technology for red-mudstone subgrade are put forward. I hope all of these could provide a strong reference for the popularization and application of red-mudstone in high-speed railway.All of them have made a number of innovative achievements, including the following major areas:1. Through making research on historical application and research situation of red-mudstone in railways and roads areas at home and abroad, a detailed summary of the causes of red beds, distribution, mineral composition, chemical composition, structure properties, crack, expansion, contraction, mechanical properties of red mudstone, subgrade diseases and mechanism of them is made. On the basis of investigation results and the properities of subgrade engineering, targeted, a series of research new works have be carried out.2. The research.on physical and mechanical properties, such as compaction, strength and deformation characteristics, and water stability of representative red-mudstone samples from Suinig-Chongqing line and Dazhou-Chengdu line is made. The results indicate that compared to general railway fillings, the compacted red-mudstone has following features: big density, high strength, small deformation, soften and weak expansion to meet water. So we should take some measures to make use full of it’s advantages and avoid it’s shortcomings.3. According to the properties of subgrade bed in high-speed railway, dynamic strength, critical dynamic stress, cumulative deformation characterastics of red-mudstone of compacted red-mudstone are studied using 3-axis vibration test method for the first time, and in accordance with the test data, the dynamic accumulative deformation prediction model of red-mudstone is created. They lay the foundation for the dynamic design for red-mudstone subgrade.(1) In the condition of 25 kPa and 50kPa confining pressure, the critical dynamic stress of red-mudstone is 50kPa and 175kPa respectively; the dynamic strength increased with confining pressure and decreases with the time increases; the dynamic modulus decreases with strain increasing and confining pressure decreases; the damping ratio increases with the strain increases, and decreases with the confining pressure increasing at same strain. The actual dynamic stress of subgrade is less than red-mudstone’s critical dynamic stress, which indicates that the compacted red-mudstone will not destroy and it’s deformation will be stable.(2) Considering the influences of density, moisture content, lateral stress, dynamic stress amplitude and frequency for accumulative deformation of compacted red-mudstone, the dynamic accumulative deformation model is put forward. Based on the predict model and dynamic FEM, the deformation of the red-mudstone layer (1.7m thick) of subgrade is 3.94mm. 4. Under the guidance of the design theory of subgrade in high-speed railway, and combined with the characteristics of red-mudstone, new structures and design parameters of red-mudstone subgrade for ballastless track and ballast track, which are proved reasonable by experiment results. The red-mudstone subgrade bed for ballast track composes of 0.6m thick graded gravel, 0.2m thick sand with a composite geomembrane layer, 1.7m thick red-mudstone, and red-mudstone embankment. For ballastless track, the structures could be:①the subgrade composes of 0.7m thick graded gravel, 2.3m thick AB group fillings, and red-mudstone embankment. This type of structure can be used for plate ballastless track or sleeper buried ballastless track.②the subgrade composes of 0.4m thick graded gravel, 2.3m thick AB group fillings, and red-mudstone embankment, or composes of 0.7m thick graded gravel, 0.2m thick waterproof layer, and red-mudstone embankment. This type of structure can be used for double block ballastless track.5. The paper puts forward to a new type of structure and design parameters of red-mudstone subgrade that composed of 0.6m thick graded broken stone, 0.2m thick sand included a composite geomembrane layer and 1.7m thick red-mudstone. By using cyclic loading test on-site for the first time, the size and distribution of dynamic response such as dynamic stress, displacement, acceleration of red-mudstone subgrade in a variety of working condition are studied. The experimental result is similar to which calculated in dynamic finite element method.(1) As a major excitation equipment at the scene, ZSS50 cyclic loading equipment can meet the requirements of loads with different frequencies and amplitude which can simulate the dynamic actions of the train in different axle load of trains and at different speeds on track and subgrade .It is an important equipment to study the dynamic character of track and subgrade.(2) The maximum dynamic stress, dynamic displacement, and acceleration of red-mudstone subgrade are 43.89kPa, 0.755mm and 6.201 m/s~2; that of the red-mudstone layer are 20.58kPa, 0.529 mm and 4.166 m/s~2; At the same frequency, the axle load of trains is the main factor influencing the dynamic performance of subgrade and the impact of rainfall is limited.6. Using methods of centrifugal model test, subgrade settlement observation on-site, cyclic loading tests at the scene and numerical analysis, the different types of deformation of subgrade such as compaction settlement, cumulative settlement, are analyzed. The compaction settlement of red-mudstone subgrade in gravity is caused by multiple factors such as red-mudstone coarse granule disintegration, rheological change, the consolidation of unsaturated soil, lateral deformation and so on. The method of percentage (the ratio of compaction settlement quantity and the thickness of the subgrade) is suggested to analyse the compaction settlement of red-mudstone subgrade. According to the results of red-mudstone subgrade and field subgrade settlement observation of improved soil and centrifugate model test, the compression ratio of red-mudstone subgrade is 0.2-0.46%o, the compression ratio of improved red-mudstone subgrade is 0.12-1‰, the compression ratio of red-mudstone layer is 0.67‰, the compression ratio of improved red-mudstone layer is 0.65‰in the condition of design and construction technology of subgrade for high-speed railway at present. In the design, 1‰can be as the compression ratio of red-mudstone subgrade for high-speed railway, and the time for subgrade settlement tend to stablity may be 5 months to 7 months.7. The depth of the soften soil of subgrade caused by atmosphere rainfall or flooding is directly affected by the compaction quality of red-mudstone soil. If less coarse, big density, small porosity, the soil permeability will be small, and the atmosphere rain can only impact limited depth of subgrade. The expansion rate of red-mudstone soil is smaller, and it will decreases when the load increases. As taking some waterproof and drainage measures to red-mudstone subgrade, soil and rain are separated frome each other, so we can make the conclusion that the soften and expansion characteristics of compacted red-mudstone has a very limited impact for subgrade in high-speed railway.8. Considerating the collapse and soften properties, compaction quality, the further broken of coarse particles caused by construction machines, period and other factors, the standard of red-mudstone particle size in construction is identified, that is, the largest particle size after collapse or broken should be less than 15cm. Considerating the compaction, strength, slope stability, settlement performances, we conclude that the strength and deformation characteristics of red-mudstone can meet the requirements of embankment in high-speed railway. Considerating the dynamic strength, dynamic accumulated deformation, dynamic responses of red-mudstone subgrade bed, as well as the subgrade bed structure, we conclude that the dynamic characteristics of red-mudstone soil can meet the requirements of subgrade bed in high-speed railway. Considerating soften and expansion characteristics of red-mudstone, the waterproof and drainage measures of subgrade, we conclude that the water stablity characteristics of red-mudstone soil will impact red-mudstone subgrade a little. Finally, we can believe that using red-mudstone to fill subgrade in high-speed railway is appropriate.9. The compacted, strength, water stability characteristics of the improved red-mudstone are studied and the work performance of the improved red-mudstone subgrade is researched by the methods of centrifugate model test, subgrade settlement observatio, cyclic loading test on-site. The results indicate that the improved red-mudstone has the characteristics of high strength, lower deformation, good water stability, uneasy softening in the water, and can satisfy the requirements of strength, stability and durability. It indicates that using red-mudstone as the fillings of subgrade in high-speed railway is feasible.10. According to the characteristics of red-mudstone as well as the improved soil and the engineering experience, the paper sums up the key technologies of design and constructon of red-mudstone subgrade in high-speed railway which includes some contents related with design and construction, such as selection principle of fillings, quality standard for compaction, structure and shape of red-mudstone subgrade, drainage, reinforcement, slope protection, construction techniques and so on. All of them are proved reasonable by various tests. The design and construction technology of red-mudstone and it’s improved soil subgrade provide a strong reference for the popularization and application of red-mudstone in high-speed railway, and have significant social and economic benefits. The results reach internationally advanced level.更多还原