Research On The Performance Of Retaining Wall With Unbonded Prestressed Reinforcements In Stage Distribution

As a new technology,the core of unbonded prestressed reinforced earth is to apply pretension on the reinforcement and make side pressure plate,prestressed reinforcement and wall panel work together to provide active constraints on filler.Moreover,applying pretension on the reinforcements can improve the overall performance of the reinforced earth structure.The arrangement of prestressed reinforcements,the pretension value and the pretension loss will directly affect the mechanical properties of the reinforced body.The study of these factors can help to reveal the working mechanism of the unbonded prestressed reinforced earth.In this study,scale model tests were conducted to investigate the technology of unbonded prestressed reinforced earth.Two experimental cases for the model tests of unbonded prestressed reinforced retaining wall with stage-distributed reinforcements were performed,and the comparative analysis of the experimental results were carried out.The obtained results are as follows:(1)Using steel grit as filler solves the similarity ratio of the scale model tests effectively.Strength indexes of the mixed steel grit are consistent with that of the non-cohesive filler in reinforced earth prototype.Moreover,the experimental model can be used to simulate the stress field of the prototype.(2)Two reinforced retaining wall scale model tests were completed,and the two models had the same amount of reinforcement.The reinforcement length of each layer increased by the same proportion from top to bottom,but the reinforcement material length's proportion of adjacent layers were different.The basal soil pressure,the displacement of wall panel,the vertical settlement displacement at the top of the soil,distribution of the lateral pressure on panel and the loss of pretension were analyzed according to the test results.(3)The measured basal earth pressure values of two cases show that the measured basal earth pressure values of reinforced body is less than the calculation value of basal earth pressure caused by the dead weight of the filler,and the basal earth pressure within the range of reinforced body is larger than that outside of the reinforced body.The pretension applied on the unbonded prestressed reinforcements make the lateral pressure on panel significantly increased and make constraints provided by the baffle on the filler increased.Both the carrying capacity and deformation resistant capacity of filler between the baffle panel and side pressure plate are also increased.According to the measurement of pretension applied on the unbonded prestressed reinforcement,the change of pretension showed that the influence between adjacent prestressed reinforcements was the main reason for the corresponding loss of pretension.In order to solve the reducing constraints on the filler caused by the loss of pretension,applying second tensioning on reinforcements from top to bottom should be taken to supply pretension after the completion of construction.(4)The measured earth pressure of the filler between the adjacent layers of lateral pressure panel are all less than the Rankine's active earth pressure at that location.It can be indicated that the unbonded prestressed reinforced earth structure has higher overall stability.