Dynamic Response Analysis Of High-speed Railway Loess Subgrade Pile-slab Structure

Pile-slab structure is a composite subgrade structure composed of sheet-pile-soil.In recent years,with the acceleration of the construction of high-speed railways,the application of pile-slab structures in subgrades has become more mature.The loess subgrade has a certain structure and poor water stability.The response of the pile-plate structure to dynamic load and water content directly affects its engineering applicability.In this paper,the applicability of the shallow-buried pile-slab structure in loess area is studied on the background of the subgrade engineering of the shallow-buried pile-slab structure in the collapsible loess area of the Baolan Line.Based on the shear test study of the remolded loess-concrete interface,the pile-soil structural plane parameter test was carried out to solve the key parameter problem of numerical simulation.The dynamic response simulation analysis of the pile-slab structure and the pile-less slab structure subgrade form was performed using FLAC3 D.Comparatively studied the distribution law of dynamic stress and dynamic displacement of the two subgrade forms,and discussed the rationality of the two subgrade structures applied in practical engineering;further simulated the loess subgrade pile-slab structure at different dynamic load speeds and water content of contact surfaces The settlement law of the pile body and the soil around the pile is affected by the rate.The main conclusions and innovations are as follows:(1)The shear test of the contact surface between remolded loess and concrete was carried out.As the moisture content increased,the shear stress-shear displacement curve of the contact surface changed from ideal elastic-plastic to non-linear elastic-ideal plasticity with tangential stiffness.Decreased,the cohesion of the contact surface is reduced.(2)Compared with the pile-slab structure roadbed,the stress distribution of the pile-slab structure roadbed in the loess area is uneven,and the stress concentration and dynamic displacement are likely to occur at the contact between the pile and the foundation and the pile and the bearing plate.(3)As the dynamic load increases,the displacement of the pile-slab structure decreases,and the settlement of the soil around the pile increases,but the displacement of the pile is always greater than the displacement of the soil around the pile,that is,the pile plays a supporting role,but the pile Increasing inconsistency in soil settlement.(4)As the water content of the contact surface increases,the vertical displacement of the pile increases non-linearly.When the water content exceeds 13%,the vertical displacement of the pile changes significantly.With the increase of the moisture content of the contact surface,the settlement of the soil around the pile increases significantly within 1/3 of the pile top,but the increase in the lower range is not obvious.