高铁有砟轨道路基面动变形分析方法及可靠度研究

Dynamic deformation analysis method and reliability on the subgrade surface of the high-speed ballast track

路基面动变形是高铁路基设计的控制标准之一,其影响因素具有一定的不确定性,因此对其进行可靠度研究显得至关重要。利用布氏解公式,得到了列车荷载作用下路基面动变形的确定性计算模型。在确定性计算模型的基础上,引入列车动轴重、基床表层及基床底层弹性模量的变异性,得到了路基面动变形的概率分布。根据《铁路路基极限状态设计暂行规范(试行)》规定的路基面动变形不超过1mm的要求,建立了列车荷载作用下路基面动变形的极限状态方程;通过可靠度指标对参数的敏感性分析,分析了列车动轴重、基床表层及基床底层弹性模量的均值、变异系数等控制因素的影响作用,并以根据目标可靠度指标所确定的变异程度控制范围作为路基设计的控制标准。结果表明,列车荷载作用下路基面动变形服从对数正态分布,且同时受到基床底层弹性模量、动轴重的均值和变异性的显著影响。确定性分析与可靠度分析相结合能够更有利于高铁路基的安全设计。

The present paper is to make a reliability assessment for the dynamic deformation on the subgrade surface of the highspeed ballast track.For the said purpose,we have to make a rather comprehensive study over the main control standards in designing the high-speed subgrade and all the influential factors of the dynamic deformation,including the dynamic stress of the subgrade and the elasticity modulus both of the surface and bottom layers of the subgrade,for they may imply lots of uncertainties.Seeing the above said necessities,we have proposed an analytical model for predicting the dynamic stress and dynamic deformation probabilities of the high-speed subgrade with the Boussinesq method.Furthermore,we have also introduced the field data to verify the effectiveness of the proposed model,on which we have worked out the deterministic model,the probability distribution and accumulative probability distribution model from the point of view of the dynamic deformation of the said subgrade surface while taking into full account the variability of the dynamic stress of subgrade,along with the elasticity modulus of the surface layer and bottom layer of the subgrade.According to the Interim Code for the optimal design of the railway subgrade（Trial）,it would be possible to confine the dynamic deformation of the subgradeunder the rail-carriage loading less than 1 mm.Therefore,it would be possible to develop an optimal state equation of the dynamic deformation of the aforementioned surface by joining the optimal value of 1 mm with the proposed deterministic calculating model,so as to work out the reliability index with the MonteCarlo method.What is more,we have also done the sensitivity analysis of the dominant parameters based on the reliability index,the effects of the mean values and the coefficients of variations（COVs） of the stochastic parameters.Besides,suppose the target reliability index is 2.5,it would be possible to make the variability sphere of the parameters as the control standard of the surface as well as the bottom layer of the subgrade.Thus,it can be found that the dynamic deformation of subgrade surface caused by the train loads should be approximate to the log-normal distribution,which is significantly influenced by the mean values and COVs of the dynamic stress of subgrade as well as the elasticity modulus of the bottom layer of the subgrade.It would be beneficial for the safety design of high-speed railway subgrade on the condition if the deterministic computational model and reliability analysis can be combined to estimate the dynamic deformation of the subgrade surface.