基于冻胀变形的基床表层疲劳寿命预测与分析

Prediction and Analysis of Fatigue Life of Surface Layer of Subgrade Based on Frost Deformation

季节冻土区的铁路建设面临着路基冻胀问题,周期性的循环冻融作用将会加剧路基结构的破坏,从而缩短路基结构的使用寿命。根据基床表层冻胀变形结果,建立基于人工变形边界的应力计算模型,并引用半刚性基层材料疲劳寿命计算公式,分别计算不同水泥添加量下的基床表层的使用寿命。计算结果表明:基床表层的最大拉弯应力随着冻胀波长的不断增大和冻胀量的不断减小而呈现增大的趋势,水泥添加量为0、1%、3%、5%时,对应的基床表层冻胀变形所导致的基床表层最大拉弯应力分别为31.2、57.6、69.0、75.1 k Pa;随着水泥添加量的增加,基床表层的使用寿命不断提高,水泥添加量分别为1%、3%、5%时,基床表层的使用寿命相较于不添加水泥的情况分别增加了27%、36%、48%。

The construction of railway is faced with the problem of subgrade frost heaving in seasonally frozen ground. Cyclic freezing and thawing will exacerbate the destruction of subgrade structure and thus shorten the service life. According to the results of subgrade frost heave deformation,this paper presents a stress calculation model based on artificial deformation boundary and cites the formula for calculating the fatigue life of semi rigid base materials. On this basis,the service life of the surface layer of subgrade with different cement content is calculated. The results show that with the increase of wavelength of frost heave and the decrease of frost heaving amount,the maximum tensile bending stress of the surface layer of subgrade tends to increase. When the cement content is 0、1%、3% or 5%,the maximum tensile bending stress of the surface layer of subgrade caused by frost deformation is calculated as 31. 2、57. 6、69. 0 k Pa and 75. 1 k Pa respectively. With the increase of cement content,the service life of surface layer of subgrade increases. When the cement content is 1%、3% or 5%,the service life of surface layer of subgrade is increased by 27%、36% and 48% compared with those without cement addiction.