动荷载与冻融相互作用对高铁路基沉降的影响

摘要

研究目的:近年来,我国高铁发展迅速,高铁路基沉降问题引起工程界高度重视.季节冻土区路基沉降问题研究尚属起步阶段,相关的研究还有待深入.本文从季节冻土地区高铁路基特点出发,针对高铁动荷载与冻融循环过程的相互作用,研究路基沉降的类型、机理及发展变化规律,给出路基沉降量的计算模式及方法,并给出算例加以验证.研究结论:(1)动荷载与冻融循环相互作用,在不同循环阶段产生沉降的性质与机理也不相同;(2)季节冻土地区路基沉降分为压缩沉降、压密沉降和热融沉降,从沉降量大小分析,冻土升温融化阶段产生的沉降量最大;(3)沉降量主要受土中的成分如气体、未冻水及矿物颗粒的影响,在动荷载作用下孔隙率变化是影响沉降的重要因素;(4)本研究成果可为季节冻土地区路基设计、维修等提供参考,也可为高铁路基沉降控制设计及施工提供依据.%Research purposes:In recent years,the high-speed railway in China has developed rapidly,and its subgrade settlement has attracted more and more attention from the engineering community.But the research of subgrade settlement in seasonal frozen soil area is still in its initial stage.In this paper,first we study the characteristics of the high-speed railway subgrade in seasonal frozen area and the interaction between dynamic load and frozen-thaw cycles.Then we study the types,mechanism and development law of subgrade settlement.Finally we give a calculation model,method and an example.Research conclusions:(1) Under the interaction between dynamic load and frozen-thaw cycle,subgrade settlement has different nature and mechanism in different cycle stages.(2) The subgrade settlement in seasonal frozen soil area includes compressibility settlement,pressure-dense settlement and thaw settlement.The maximum volume of settlement is produced during thawing of frozen soil.(3) The mechanism of settlement is mainly affected by the composition of soil,such as gas,unfrozen water and mineral particles,and under dynamic load the change of porosity is an important factor affecting the settlement.(4) The results of this paper can provide reference for subgrade design and maintenance in seasonal frozen soil area,and provide basis for the design and construction of high-speed railway subgrade settlement control.