高速铁路无砟轨道路基上拱变形整治研究

Study on Improvement of Overarching Deformation of Ballastless Track Subgrade of High-speed Railway

研究目的:随着国内高速铁路飞速发展,高速铁路网覆盖范围越来越大,遇到的地质条件趋于多样化与复杂化,运营过程中病害类型较多,其中无砟轨道路基上拱变形问题在近年陆续显现,严重影响轨道的平顺性与行车安全,因此有必要深入研究其上拱变形的机理和整治方案,以确保高铁高速运行的安全。研究结论:(1)高速铁路路基填料应特别警惕硫铁矿伴生的硫酸钙盐矿物含量,其与水结合吸收结晶水发生水化反应形成二水硫酸钙,导致体积竖向膨胀上拱2.68%~6%,具有遇水膨胀但失水不收缩的特性;(2)上拱变形规律是冬春季细雨低温下填料含水量不断上升导致上拱膨胀量持续增大;夏秋季升温蒸发后失水,含水量减小,膨胀上拱趋势减弱;大气降水影响填料膨胀变形的深度在1~2.3 m;(3)轨道板下膨胀填料单元整体受力处于非刚性有限约束,基床表层及基床底层的折减经验系数宜分别按0.45与0.55取值;(4)在不同的限制条件下宜采用不同的整治方案,开通前或有单线封锁条件的情况下可采用揭板明挖法,在限速运行及天窗条件下宜采用暗挖置换方案;(5)本文所述各方案整治效果明显,整治经验可为今后类似工程提供借鉴与参考。

Research purposes:With the rapid development of high-speed railway in China,the coverage of high-speed railway network is getting larger,the geological conditions tend to be diversified and complicated,and there are many types of diseases in the operation process.Among them,the overarching deformation problem on ballastless track subgrade has emerged in recent years,which seriously affects the track comfort and driving safety.Therefore,it is necessary to deeply study the mechanism of overarching deformation and treatment plan to ensure the safety of high-speed railway operation.Research conclusions:(1)The content of calcium sulfate mineral associated with pyrite in the subgrade filler of high-speed railway should be noted,which combines with water and absorbs crystal water to form calcium sulfate dihydrate,resulting in volume expansion of 2.68%~6%.(2)The deformation law of the upper arch is that the expansion of the upper arch increases continuously due to the continuous increase of the water content of the filler under the low temperature of light rain in winter and spring.In summer and autumn,water loss occurs after heating up and evaporation,and the trend of the expansion of the upper arch weakens when the water content decreases.The depth of the expansion deformation influenced by atmospheric precipitation is about 1~2.3 m.(3)The overall force of the expansion packing unit under the track plate is under non-rigid finite constraint,and the empirical reduction coefficients of the surface and bottom layers of the foundation bed should be 0.45 and 0.55,respectively.(4)Different schemes should be adopted under different limiting conditions.Before opening or under the condition of single line blockade,the uncovering and open digging method can be adopted.Under the condition of speed limiting operation and skylight,the underground digging replacement scheme can be adopted.(5)The above schemes have obvious effects,and the successful remediation experience can provide references for similar projects in the future.