高速铁路过渡段路基附加沉降机理与计算方法研究

The control of additional settlement under long-term dynamic loads, is a key technology in design and construction of high-speed railway. The differential settlement control of the transition sections between soil subgrade and rigid structure like bridge, tunnel and culvert is particularly important. But the corresponding researches are far lagging behind the needs of engineering practice for lacking of technology data and mature computation theories. The methods of in-situ train-induced vibration tests, laboratory experiments, theoretical analysis and numeric calculations will be adopted systematically in this project to study on the dynamic characteristics under long-term train-loads of the transition sections subgrade for high-speed railway, the cumulative plastic deformations of coarse grained soil used for subgrade materials, the influence of the additional settlement for the time-dependent behaviors of subgrade dynamic stresses and subgrade dynamic parameters induced by non-homogenous settlements. The calculation methods for the additional settlement of transition sections subgrade for high-speed railway will be established, which will be able to consider the development process of non-homogenous settlements. The influence law and degree of the differential settlement for the transition subgrades material type, design scheme and driving factors will be analyzed. Based on it, the mechanism of the differential settlement will be revealed. These achievements can provide the scientific basis for the calculation methods of the additional settlements and for evaluating the long-term dynamic stability of transition sections subgrade for high-speed railway. The researches have important value in theory and application.

高速列车长期动力荷载作用下的附加沉降控制是高速铁路无砟轨道路基设计与施工的关键技术之一，刚性结构物（桥、隧、涵）与路基间过渡段的沉降差控制尤为重要，然而目前相关资料积累不多，计算理论尚不成熟，研究远滞后于工程需要。本项目拟采用现场测试、室内试验、理论分析和数值计算相结合的方法，对高速铁路过渡段路基在长期动载下的动力特性、粗颗粒路基填料累积塑性变形、过渡段不均匀沉降引起的路基动应力与动参数时变性对附加沉降的影响等问题进行系统深入研究，建立能考虑不均匀沉降发展过程的高速铁路过渡段路基附加沉降计算方法。分析过渡段路基填料类型、设计方案、行车因素等对附加沉降差的影响规律及程度，并在此基础上揭示沉降差的产生机理。研究成果可为高速铁路过渡段路基的附加沉降计算和长期动力稳定评估提供科学依据。具有重要的理论意义和工程应用价值。

刚性结构物与土质路基之间的过渡段是高速铁路无砟轨道路基中的一个薄弱部分，过渡段的长期动力稳定性是影响高速铁路在长期运营过程中的安全性和舒适性的关键因素，过渡段的附加沉降产生机理已成为高速铁路的重要科学问题。本项目深入分析了正式运营前、后过渡段路基的动响应测试结果，得到了过渡段的振动优势频率及其对应的激励原因，获得了路基刚度以及行车因素对过渡段振动频域特性和时域幅值的综合影响规律，提出了系统评价过渡段长期动力稳定性的方法和结论，可为相似工程设计、线路运营维护提供重要参考。本项目开展了过渡段填料的室内土单元模型试验，得到了填料在长期循环动载作用下的累积塑性变形特性和计算模型，研制了过渡段附加沉降差演化特性研究的模型试验系统。本项目建立了高速铁路过渡段的列车-轨道-路基系统耦合动力仿真模型，结合室内试验结果获得了附加沉降的演化特性，通过多种工况下过渡段的动响应计算和附加沉降分析，揭示了过渡段附加沉降差产生的内在机理。基于过渡段与普通路基填料的动力特性差异，提出不平顺条件下过渡段附加沉降的计算方法，具有重要的科学意义。通过室内外试验获得了风化花岗岩改良土、红黏土的动力特性，通过仿真计算、预测分析方法得到了长期动载作用下改良土路基的附加沉降特性以及红黏土路基的工后沉降预测结果，为风化花岗岩改良土、红黏土应用于过渡段填筑的适宜性提供了依据，具有重要的工程意义。