Research On Static Performance Of Unbonded Prestressed Reinforced Earth Retaining Wall Under Top Load

The unbounded prestressed reinforced earth retaining wall employed the prestressing tendon to make the wall panel and side-pressuring panel apply active restraint on the filler.The prestressing tendon connects the wall panel and sidepressuring panel and is stretched to make the two plates apply horizontal pressure on the filler.Therefore,the filler,wall panel,side-pressuring panel,and prestressing tendon together form a whole stiffened body.The unbounded prestressed earth reinforced retaining wall is still a flexible supporting structure.Based on filler packing density increment method,the research conducted the indoor scale model test on the type of retaining wall.It also analyzed the distribution and development pattern of the wall panel’s horizontal displacement,top vertical displacement,pretension loss,horizontal earth pressure and earth pressure in base,during construction and loading period.It studied how different degree of pretension and loading procedure affected the performance and bearing capacity of retaining wall.Meanwhile,the research used finite element analysis to study the effect of load position on the retaining wall’s mechanical properties.The following research results are obtained:(1)After pretension was applied,wall panels in each layer moved towards the retaining wall.The top surface of the reinforced area swelled.Those phenomena are more obvious as the pretension stress increases.Pretension significantly increases horizontal earth pressure in reinforced area and earth pressure in base.Also,the pretension stress has a diffusion effect,which causes the filler’s horizontal earth pressure to distribute large in both ends but small in the middle,along the long axis of prestressing tendon.(2)The deformation resistance of prestressed retaining wall is better than nonprestressed retaining wall.Prestress could effectively enhance the bearing capacity of the retaining wall.What’s more,the top of the wall is a weak area of the retaining wall,certain methods like increasing the constraint of filler in the top area should be taken to enhance the bearing capacity of retaining wall.(3)Uneven settlement occurred in non-reinforced area when the top load was about to reach the ultimate load.The area which is closer to the reinforced area is detected with bigger settlement.Based on the uneven settlement,it could be predicted that the retaining wall is reaching its critical state of bearing capacity under this condition.(4)After loading,the horizontal earth pressure in the reinforced area decreases with the loss of pretension of the prestressed reinforcement.However,the maximum decrease of horizontal earth pressure in the first to third layers is much smaller than the loss of pretension.The additional horizontal and vertical earth pressures caused by the top load have a diffusion effect.The side-pressuring panel effectively blocks the diffusion of the additional vertical earth pressure caused by the top load in the nonreinforced area to the reinforced area.(5)According to the numerical simulation test on top load position change,the most vulnerable loading position is at the non-reinforced area.Furthermore,when there is load on top of the reinforced area,the deformation resistance of the retaining wall is strengthened.