高速铁路路基长期动力稳定性评价方法研究

Currently, the long-term dynamic stability evaluation of railway subgrade bed is based on critical dynamic stress in China. However, the long-term dynamic stability of high-speed railway subgrade bed is not only decided by the strength but also the deformation. The critical dynamic stress can not meet the development of highspeed railway. Rely on two types of subgrade bed which are constructed on swelling soil and red clay foundtion along the YunGui highspeed railway. Obtained the dynamic evaluating parameters such as shear strain, dynamic strength, dynamic shear modulus and damping of the two types of soil by the dynamic triaxial test, Fatigue dynamic triaxial test, Resonant(Vibration) column test and in-situ cross-hole wave velocity method experiment, the changing regularity of dynamic stress, vibration velocity, acceleration along the different locations of the subgrade bed through in-situ vibration test. Combined with the experiments results, we try to introduce two new types of dynamic stability evaluation methods of the railway subgrade bed beyond the dynamic stress method, the dynamic shear strain method and dynamic effective velocity method, and improve the limitation of these three evaluation methods. To evaluate the dynamic stability of the cutting bed of Yun-Gui high-speed railway by the three improved evaluating methods and figure out the reasonable bedding replacement thickness, depth of treatment and reinforcement. Further improve the dynamic parameters and the test methods of the three new evaluating methods, study the applicability and universality of the other subgrade bed. Brought the three new evaluation methods into ＂highspeed railway subgrade bed design specification＂.

目前我国铁路路基长期动力稳定性评价采用临界动应力法，然而高速铁路路基长期动力稳定不仅是强度问题，而且是变形控制问题，现行评价方法已不能满足高速铁路发展需求。结合拟建的云桂高速铁路膨胀土、红粘土路基工程实体，进行动三轴、疲劳动三轴、共（自）振柱及跨孔波速法试验，获得两类路基的动剪应变、动强度、动剪模量和阻尼比等动力评价参数；通过现场激振试验，获得两类路基的动应力、振动速度、加速度等沿基床不同位置的变化规律。根据试验结果,在临界动应力法的基础上，引进国外的动剪应变法和有效振速法，并对这三种评价方法进行改进和完善，形成新的三种评价方法；运用三种新的评价方法对云桂高速铁路两类路基进行长期动力稳定性评价，提出合理的基床换填厚度，地基处治和加固深度,供实际工程采用。对三种新的评价方法进行通用性研究，通过相关部分评审后，将其纳入到《高速铁路路基设计规范》中。

目前我国铁路路基长期动力稳定性评价采用临界动应力法，然而高速铁路路基长期动力稳定不仅是强度问题，而且是变形控制问题，现行评价方法已不能满足高速铁路发展需求，故对高速铁路路基的长期动力稳定性进行评价是十分必要的和刻不容缓的。本课题紧密结合云桂高铁-有砟轨道和武广高铁-无砟轨道路基工程实际和关键问题，借助理论分析、室内/现场试验和数值模拟等方法，对高速铁路路基长期动力稳定性进行了研究。通过改进的动三轴试验系统、共（自）振柱及跨孔波速法试验，获得了两类路基土的动剪应变、动强度、动剪模量和阻尼比等动力稳定评价参数；通过实车测试、现场激振试验和数值仿真模拟方法，获得了两类路基的动应力、振动速度、加速度等沿基床不同位置的衰减变化规律；基于试验结果，对临界动应力法、动剪应变法和有效振速法三种评价方法进行了改进和完善，形成了三种更加具体和完善的评价方法；运用三种新的评价方法对云桂线和武广线高速铁路两类土质路基进行长期动力稳定性评价，提出了合理的基床换填厚度、地基处治和加固深度，供实际工程借鉴和采纳；运用结构可靠度理论对高速铁路路基系统的稳定性进行了应用探索，为高速铁路路基极限状态法设计和工程应用奠定了理论基础；对三种新的评价方法进行通用性研究，通过相关部门评审后，可将其纳入到《高速铁路设计规范》中。