高速列车动载下岩溶区铁路路基动力响应分析OA

High-speed railway subgrades in karst-prone areas may experience soil loosening,cumulative deformation,and even soil-cavity collapse under long-term train-induced vibrations,thereby threatening ride comfort and operational safety.To address this problem,a method combining field vibration monitor-ing with three-dimensional dynamic numerical simulation is proposed to analyze the dynamic response of railway subgrades overlying karst soil cavities.First,field vibration tests are conducted on a typical high-speed railway subgrade section prone to karst collapse.Soil vibration acceleration responses during train passage were recorded,and time-frequency analysis is used to systematically examine the frequency distri-bution and attenuation characteristics of environmental vibrations.Next,based on multibody dynamics and finite element theory,a refined three-dimensional coupled dynamic vehicle-track-subgrade-foundation model incorporating a soil cavity is developed to analyze the dynamic response of the subgrade under train loading.Finally,multi-case parametric analyses are performed using the numerical model to reveal how soil-cavity burial depth and radius affect vibration propagation and the distribution of dynamic responses within the subgrade.The results show that environmental vibrations are concentrated mainly in the range of 0~35 Hz,with high-frequency components attenuating significantly faster than low-frequency compo-nents.The soil cavity scatters and obstructs elastic waves induced by train vibrations.Both the vertical dy-namic displacement and vibration acceleration amplitudes are markedly lower near the cavity than farther away,and the attenuation rate of dynamic displacement is higher than that of vibration acceleration,indicat-ing that displacement is more sensitive to the cavity-induced reduction in wave energy.Both amplitudes in-crease with increasing burial depth and decrease with increasing cavity radius;consequently,shallow,large soil cavities have the greatest influence on the dynamic response of the subgrade.These findings provide a reference for the disaster-prevention and mitigation design of railway subgrades in karst areas.