【作者】 詹永祥；

【导师】 蒋关鲁；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2007， 博士

【摘要】 桩板结构路基（pile-plank embankment）是高速铁路无碴轨道一种新的路基结构形式，它由下部钢筋混凝土桩基、路基本体与上部钢筋混凝土承载板组成，承载板直接与轨道结构连接，桩、板固结与土路基共同组成一个承载结构体系。它综合了无碴轨道结构与桩基础的各自特点，充分利用桩-土、板-土之间的共同作用来满足无碴轨道的强度与沉降变形要求。本文结合铁道部科技计划发展项目“遂渝线无碴轨道线下工程关键技术试验研究”专题“遂渝线高速铁路桩板结构路基”，率先在国内开展了无碴轨道桩板结构路基的深入研究，概括总结了桩板结构路基的设计理论及计算方法，通过模型试验、现场测试和数值模拟等手段，取得了一些创新性的成果，主要得出如下几方面的结论。1．从一个独立的地基处理技术体系的观点，提出了桩板结构路基这一新型的无碴轨道路基结构形式，给出了桩板结构路基的定义及其适用场合。2．系统阐述桩板结构路基的设计理论及计算方法，总结了各种状态下的荷载组合及各构件设计的关键性技术要求，参考国外无碴轨道设计，根据目前国内设计经验，给出桩板结构路基设计控制指标，按照正交试验法对桩板结构进行优化，确定了合理的设计尺寸范围。3．通过离心模型试验，对桩板结构路基的沉降特性以及桩土相互作用进行了研究。研究结果表明，桩板结构路基施工完成放置5个月后路基面累积沉降基本达到稳定，采用钢板配重来模拟列车荷载，半年左右路基面沉降达到稳定；桩板结构路基的桩基属于长径比较大的挖孔灌注嵌岩桩，其荷载传递具有摩擦桩的特性。4．以遂渝高速铁路为背景，通过大比例动力模型试验，加载频率为5 Hz和10 Hz，各激振20万次，研究在列车动荷载长期作用下桩板结构路基动力相互作用机理及其沉降变形规律。试验结果表明，在激振荷载作用下桩间土、跨中板下土体的竖向动应力幅值沿深度近似呈“K”形分布，与土体相比，桩分担了大多数动力荷载，加载频率和激振位置对动应力有影响。桩基加深了路基的动力影响范围，改善了路基土体部分的受力状态；在荷载激振1万次后桩板结构路基沉降趋于稳定，工后沉降量满足铺设无碴轨道的沉降控制要求。5．通过遂渝线现场实测，对CRH₂动力分散型机车及货车在桩板结构路基试验段高速行车条件下的动力响应规律进行了研究，分析列车速度及轴重对路基动力响应的影响。分析表明：随车速的增大，加速度及动应力均有不同程度的增加，路基动力响应受车速影响较小，受轴重影响较大；动应力随路基深度的增加而衰减，并且随着深度的增加，动应力值和静态应力值越来越接近：桩底土动应力较大，是路基动力设计的关键环节之一。6．通过有限元法，基于弹塑性理论，建立桩板结构路基整体有限元模型，该模型充分地考虑了系统的空间、时变、耦合特性，通过非线性数值模拟，分析了桩板结构路基在不同车速、不同轴重及不同跨度下动力响应的变化规律，并与部分实测结果进行了对比分析，主要得到以下结论：（1）列车时速对路基动应力、动位移影响较小，而对路基加速度影响较大：车速对桩身动应力的影响较大区域基本在桩顶以下2／3桩长范围，对桩底几乎无影响。且随着深度的增大，车速对路基的动力影响程度在减弱。（2）路基动力响应随着轴重的增加近线性增大。（3）在5～10m跨度范围内，路基的动位移、动应力随着跨度的增大而增大，而加速度随着跨度的增大而减小。通过与动力模型试验和现场行车试验对比分析可知，动力模型试验、现场行车试验与数值分析得到的桩板结构路基的动力响应规律结论一致。证明了本文建立的计算模型具有较好的可靠性和实用性。7．对桩板结构路基的总沉降及工后沉降问题进行理论与试验研究，探讨桩板结构路基的沉降计算方法；结合遂渝线计算桩板结构的工后沉降并与长期沉降测试结果进行对比分析。分析结果表明，桩板结构有效的控制了路基的工后沉降，是一种有效的路基及地基加固工法。更多还原

【Abstract】 Pile-plank embankment is a kind of new-type form of ballastless truck in high-speed railway, it is composed with the reinforced concrete plank at its upside and reinforced concrete piles, subgrade and subground at its downside, and plank directly connectes with the track structure, the piles fixedly link to plank and together with the subgrade compose a bearing load structure system. It synthesizes respective characteristic with the ballastless truck and the piles, fully depends on pile-soil and plank-soil interaction to satisfy with the intensity and the settlement requests. This paper unified Ministry science and technology development project ’study on the key technology under the line of ballestless truck in the Suining-chongqing high speed railway’ ,with the topic pile-plank embankment in the Suining-chongqing high speed railway , domestically took the lead to carry out pile-plank embankment thorough research. The design and the calculation method of pile-plank embankment were summarized, through method of model test,field test and number simulation, received some innovation results,mainly obtained the following several conclusions.1. Pile-plank embankment is not only a kind of new-type form of ballastless truck, but also an independent subground processing technology system, pile-plank embankment definition and its suitable situation are given.2. The design theory and calculation method of pile-plank embankment are proposed, the crucial specification which under each kind of load combination condition and various component designs are summarized. Based on overseas ballaseless truck design, the design control target of pile-plank embankment is given, carried on the optimized design, the reasonable design size of pile-plank embankment is received.3. Through centrifugal model test of pile-plank embankment for ballastless truck, the settlement and pile-soil interaction of pile-plank embankment are studied. It is shown that the settlement of pile-plank embankment is completed when pile-plank embankment is laid for five months; By using the steel plate counterweight to simulate the train load, the settlement of ballastless truck is completed when it is used for seven months; and the pile of the structure is rock-socketed bored cast-in-place frictional pile whose diameter is small in proportion to its length.4. Based on Suining-chongqing high speed railway, the large scale dynamic model test is established, the loading frequency is 5Hz and 10Hz, and the loading time is 200000, receives the dynamic interaction and settlement change rules. Test results indicate that the amplitude of vertical dynamic stress is approximately " K" form to distribute with depth in soil between piles and soil under the middle-span plank, piles share most dynamic stress compared with soil, dynamic stress is affected by loading position and loading frequency. Pile structure expanded the depth of dynamic response of the subgrade and improve the stress of roadbed soil, the settlements of the pile-plank embankment remain constant after 10000 times of vibrant loading, post-construction settlements satisfy with the settlement control request to build ballastless truck in high-speed railway.5. Based on the field test in Suining-chongqing high-speed Railway, the dynamic responses of pile-plank embankment on which a disperse impetus locomotive CRH₂ and freight train with high speed is running are studied, changes the dynamic responses with the speed of train and the wheel load are analyzed. The analysis indicates that the acceleration and dynamic stress grow in varying degrees with the speed of train increased. The dynamic responses of subgrade are less affected by speed of train, but are significantly affected by the wheel load. The dynamic stresses attenuate with increasing the depth of subgrade, with increase in the depth, dynamic stresses are closer to the static stress. Dynamic stress at pile-bottom soil is biggish, and is one of the key dynamic design of subgrade.6. A tri-dimensional element model has been founded, which involves the ballastless track and pile-plank system. It can provide dynamic responses of the system with changes of wheel load, vehicle velocity, frequency, irregularities, and distribution of dynamic responses in the subgrade etc. by changed the wheel load, vehicle velocity, pile-span, the dynamic response of the system were studied systematically, some results were stated as followings:（1） Dynamic stress and displacement were less affected by vehicle velocity, but acceleration was significantly affected by vehicle velocity, and dynamic stress in the pile is mostly affectd at 2/3 pile length under the pile top, and is less affected at bottom of pile, dynamic response decreases with the vertical depth increase（2） The dynamic response increases along with the wheel load increase near linearity.（3） In the 5～10m span scope,the dynamic stress and displacement increase with the span increase,but acceleration reduced with the span increase.These studies show that the results are in good agreement with the datum from tests. It proves that the dynamic model is practical and reliable.7. Studied on the theory and the test of settlement and post-construction settlement of pile-plank embankment, discussed on the calculation settlement method of pile-plank embankment, calculated the post-construction settlement in Suining-chongqing high-speed railway and carries on the contrast analysis with the long test. The result indicated that pile-plank embankment was effective control post-construction settlements of roadbed, was one kind of effective roadbed and subground reinforcement measures.更多还原