列车荷载作用下复合土样动力特性研究OA

[Objective]The study aims to reveal the dynamic behavior of sand-clay composite soils under train loading and their differences from homogeneous soils,providing experimental evidence for evaluating the dynamic response of railway engi-neering under complex geological conditions.[Methods]Using a GDS dynamic triaxial testing system,a series of consolidated undrained cyclic triaxial tests was conducted.The strain evolution,pore water pressure development,and energy dissipation characteristics of homogeneous sand,homogeneous clay,and sand-clay composite soils were compared under varying load am-plitudes and intermittent loading conditions.Quantitative indicators such as the number of vibration cycles,cumulative strain,and pore pressure variation rate were used to analyze the effects of load amplitude and intermittency.[Results](1)The strain growth pattern of composite soils differed markedly from that of homogeneous soils.In the late loading stage,the strain growth rate per 1 000 cycles reached up to 0.28%,approximately 8.8 times that of homogeneous soils.(2)Under identical cyclic loading,homogeneous sand exhibited the highest energy dissipation.(3)Pore water pressure in homogeneous sand rose rapidly and dissipated after reaching its peak,whereas the overall trend in sand-clay composite soils was similar but lacked clear pore pressure dissipation.When vibration cycles reached 8 000 or more,the pore pressure growth rate of compos-ite soils was roughly half that of homogeneous clay.(4)The inhibitory effect of intermittent loading on cumulative strain and pore pressure dissipation weakened with an increasing number of intermittent cycles.Both cumulative strain(ε')and pore pressure dissipation(u')increased approximately linearly with increasing load amplitude.[Conclusion]Under cyclic train loading,sand-clay composite soils exhibit stronger long-term cumulative deformation tendencies and distinct pore pressure re-sponse characteristics.Intermittent loading and load amplitude are critical factors affecting the dynamic stability.The results provide experimental references for the durability design and safety assessment of railway and near-surface engineering under multilayer soil conditions.