Study on Calculation Method for Tensile Force of Geogrid in Reinforced Cushion of Subgrade

Research purposes: The geogrid has the features of the stress dispersion,adjusting pile-soil stress ratio,improving the foundation bearing capacity and decreasing the uneven settlement,so it is widely used in the railway composite foundation.But now there is no unified calculation method for the tensile force of the geogrid,so it is necessary to do the research on the calculation method for the tensile force of the geogrid in order to provide the reference to the design of the reinforced cushion of railway composite subgrade. Research conclusions:Taking the Wuhan-Guabgzhou Passenger Dedicated Line as the engineering background,the different calculation methods for the tensile force of the geogrid were summarized.The plane finite element analysis model was established.The variation laws of the subgrade settlement,the load on the geogrid and the pile-soil stress ratio in process of subgrade filling were analyzed on consideration of the different geogrid modulus conditions..After the soil filling to a certain height,the increases of subgrade settlement,the load on the geogrid and pile-soil stress ratio became slow.The increase of geogrid modulus led to the obvious increase of the load on the geogrid.The use of reinforced cushion could effectively solve the problem of thestress concentration on the pile top problems and control the subgrade settlement.