阴阳坡效应下季冻区铁路路基水-热-力行为与轨道不平顺规律研究

Railway subgrade thermal-hydro-mechanical behavior and track irregularity under the sunny-shady slopes effect in seasonal frozen regions

阴阳坡效应会影响高速铁路路基温度场的分布规律,导致路基表层产生不均匀冻胀变形,进而造成无砟轨道产生静态不平顺,影响高速列车运行的平稳性和舒适性。本文建立了考虑阴阳坡效应的冻土水-热-力耦合模型,探究了季冻区高速铁路路基在冻结过程中温度场发展过程以及土体的变形特性,分析了不均匀冻胀变形作用下的CRTSⅢ型板式无砟轨道钢轨不平顺变化规律。计算结果表明:高速铁路路基左右侧边坡由于所受太阳辐射量不同,阴坡冻结时间早于阳坡,而融化时间却晚于阳坡,这是引起路基不均匀冻胀的关键因素。不同线路走向会影响路基上部的温度变化和表层冻胀量,从而使无砟轨道结构变形存在差异。当线路为东北走向时随着走向角的不断增大,下行线的轨道水平不平顺不断减弱,上行线轨道水平不平顺则稍有增加,最终在南北走向时二者趋于一致。因此,在季冻区铁路选线时应最大程度避免东西走向,以尽可能减弱极端情况下的路基阴阳坡现象。

The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static irregularity in the slab track.Based on the hydraulics theory,a thermal-hydro-mechanical(THM)coupled model of frozen soil is established and verified.We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track SystemⅢslab tracks under uneven frost heaving deformation.The results show that,because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation,which is the key factor causing uneven frost heaving of subgrade.Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface,leading to differences in the deformation of the slab track structure:Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line,and these become consistent in north-south directions.Therefore,when selecting railway lines in seasonal frozen areas,the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades.