高铁软土路基工后沉降控制效果“变形-状态”机理分析

Operating mileage of China’s high-speed railway has totally extended upward to around 22,000 kilometers, on the top of the world ，take up 60% of the world‘s. The excellent construction work makes the strategy of “High-speed railway exportation” currently becomes the so-called “The Prime minister project” and “The symbol of Chinese diplomacy” of the administration. However, it is rather limited by the issue of post-construction settlement control technology, which is also regarded as a scientific challenge worldwide. In this context, the application of research plan aims at controlling the post-construction settlement on the basis of systematical analysis on its mechanism. For this purpose, a comprehensive method consisting of the numerical simulation methods, laboratory experiments, and full size in-situ experiments is designed in the project. The major issues include: a systematical identification of post-construction settlement at construction and operation stages based on the life-cycle management, and a synergetic analysis principle using composite standards. At one hand, settlement data for in-situ monitoring is used as a direction verification, so that the interaction mechanics among the post-construction settlement, the environment, and engineering measures can be proposed. It will be beneficial to improve the designing methods for subgrade engineering of high-speed railway. On the other hand, the data from TQI test are incorporated as an indirect verification. The internal relation between the grade of settlement deformation and the status of the railway track represented by TQI will be further explored. The concept of engineering vulnerability, which is first proposed by the applicants will be used in this field to form a core idea that incorporating settlement deformation with the status of railway track. The study in the application is expected to play an important role in assessing the controlling effect of subgrade settlement of high-speed railway, which is also known as serving status of the subgrade.

我国高铁的运营里程已达世界第一（2.2万公里,世界的60%），作为总理工程与外交名片的“高铁走出去”国家战略，仍然遇到工后沉降控制效果不佳的世界性难题。据此，拟开展高铁路基工后沉降控制效果机理分析系统研究。拟采用数值模拟为先导、室内模型试验与足尺试验相结合攻克关键难题、现场试验验证成果挖掘创新点的研究思路为手段；基于全寿命管理理念，系统识别建设期与运营期高铁路基工后沉降控制效果影响因素，提出工后沉降控制“双标准”协同分析思路。一方面，沉降（值）监测直接验证，建立高铁路基工后沉降控制效果与工程措施及环境影响互馈机制，完善与发展高铁路基工程设计与计算方法，揭示高铁路基工后沉降控制效果的内在机理。另一方面，将TQI检测作为工后沉降控制效果的间接验证，探索TQI值代表轨道状态与沉降变形等级的映射关系，并基于申请者提出的工程易损性理念，建立以沉降变形-轨道状态协同考虑为核心思想，评价高铁路基沉降控制

高速铁路软基工后沉降控制效果一直世界难题，以往工后沉降控制效果主要围绕变形量分析。本项目研究将影响因素从工程措施延伸到运营期风险因素，建立工后沉降控制效果全生命周期影响因素机理分析方法；结合TQI值监测，构建了工后沉降控制效果“变形-状态”机理分析方法，简述如下：.1.监测与预测获取了京沪与沪宁高铁路基工后沉降规律，将其控制效果分成四个等级（沉降超限>15mm、临界超限10-15mm、基本合格5-10mm、及合格<5mm）。为高速铁路工后沉降控制效果提供成功案例。.2.实测与理论分析得出了高速铁路工后沉降控制效果影响因素。①工程措施：工后沉降控制效果排序：桩-板最优、桩-筏、桩-网最弱；刚度大的PHC/CFG桩-网优于砂桩-网；②建立运营期风险（地下水位、临近基坑开挖或抽水、路基病害治理、列车动载）等环境扰动因素对工后沉降控制影响机理与规律。掌握了“工程建造因素与运营期风险”对控制工后沉降影响机理与规律。.3.建立了工后沉降控制效果机理分析的“沉降计算理论与方法”。推导了端承型、悬浮型刚性桩-筏复合地基固结方程及其解析解与影响因素；提出基于改进Terzarghi算法的桩网地基桩土应力计算方法。提出了基于荷载传递理论的刚性桩-筏复合地基加固区沉降计算方法；建立基于分离动、静荷载沉降的思路，动力作用沉降计算方法。提出高压旋喷注浆加固区路基沉降计算方法；形成基于区域沉降与动态神经网络沉降方法。建立了邻近基坑开挖及降水造成的地表沉降计算方法。为高速铁路工后沉降控制，提供工程设计方法与运营期风险应对技术措施。.4.基于工后沉降等级划分与推算、以及相应TQI值变化规律，将高速铁路工后沉降划分成“稳定、基本稳定、临界超限和超限”四种状态，构建高铁路基工后沉降控制效果“变形-状态”分析方法。为高速铁路的养维的“计划修”提升到“状态修”提供理论支持。