不同载荷频率下有砟铁路道床累积沉降特性的离散元分析

为研究有砟道床在高频载荷作用下的累积沉降规律,建立工程尺度下枕木-有砟道床的离散元计算模型。考虑道砟的非规则真实几何形态,利用不可破碎的簇颗粒模型近似构造。在10 Hz～100 Hz载荷频率区间内,对比分析枕木位移以及道砟颗粒在垂向和横向上的运动分布规律,研究分析道床在循环正弦载荷作用下的动力特性。数值结果表明,在载荷频率不超过60 Hz时,道床累积沉降随着载荷频率的提高而逐渐增大;当载荷频率超过60 Hz时,道床累积沉降随着载荷频率的提高而急剧增大,并在载荷频率为80 Hz时达到最大值,而后道床累积沉降量随着频率的提高反而逐渐减小。此外,分析对比不同载荷频率下道床速度场分布及典型位置道砟的加速度等物理量,发现80 Hz的载荷频率下道床离散元模型的振动最强烈。

DEM analysis of accumulated settlement characteristics of railway ballast bed under dynamic load with various frequencies

To investigate the characteristics of the accumulated settlement of a railway ballast bed under high-frequency load,the discrete element method (DEM) of a sleeper-ballast bed with engineering scale was established using the GPU high performance parallel computing algorithm.Considering the real irregular geometry morphology,the ballast particles are constructed with unbreakable clustered spheres.In the frequency interval of 10Hz~100Hz,the dynamic characteristics of the ballast bed were analyzed and compared with the vertical displacement of the sleepers,as well as the movement distribution and vibration response of ballast in vertical and transverse directions.The simulation results show that the ballast accumulated deformation gradually increases with the increase of load frequency if it is lower than 60Hz.The ballast accumulated deformation increases rapidly with the increase of load frequency if it is greater than 60Hz,and reaches the maximum if the load frequency is 80Hz.After that,the ballast accumulated deformation decreases gradually along with the increases of load frequency.Moreover,physical quantities,such as the velocity field of the ballast bed,acceleration of ballast particles at different positions are compared at different frequencies.It shows strong vibration occurs on the DEM model of the ballast bed when the load frequency is close to 80Hz.