Study On Prestress Control Of Unbonded Prestressed Reinforced Body

The prestress of reinforcement directly influences the stress distribution of the filler,and then affects the safety of unbonded prestressed reinforced earth retaining wall.The key to design the retaining wall is to determine the prestress control value of reinforcement.A numerical method was used to study the development of plastic zone,the distribution of filler stress and the reasonable range of prestress of full prestressed reinforced earth retaining wall under single-layer prestress action.On this basis,the static performance and bearing capacity of retaining wall under three kinds of vertical load arrangement were studied.The influence of prestress level on the vertical bearing capacity of retaining wall was also studied by changing the prestress value of prestressed reinforcement.Present study obtains the following research results:(1)The increase of prestress will cause a penetrating plastic zone appears around the side plate.The horizontal stress of filler increases significantly with the application of prestress,the value of which is large at ends and small in the middle along the direction of reinforcement.The average failure ratio of filler is decreased first and then increased with the increase of prestress coefficient.The stress level of filler indicates that there is an optimal safety state of filler under the action of prestress.(2)The reasonable range of prestress can be controlled by the optimal safety state and the penetration of plastic zone.The parameter analysis shows that with the internal friction angle and cohesive force of the filler,the length of the prestressed reinforcement and the height ratio of the wall increase,the upper limit value and the lower limit value are obviously increased,while the side plate size has no effect on the upper limit value and the lower limit of the reasonable range of prestress.(3)Under three kinds of vertical load arrangement,the vertical bearing capacity of the retaining wall is controlled by deformation,and the maximum horizontal displacement of the retaining wall appears on the top of the wall panel.The vertical load acting on the reinforced area is helpful to improve the resisting deformation ability of the retaining wall,so as to improve the supporting effect of the retaining wall on its rear filler.(4)The tensile value on the prestressed reinforcement is mainly caused by the gravity load and the prestressing force on the prestressed reinforcement of that layer.The prestress of the prestressed reinforcement in the adjacent layer will cause the decrease of the tensile value of the prestressed reinforcement,but the prestress of prestressed reinforcement in non-adjacent layers has no effect on the tensile value of the prestressed reinforcement in this layer.(5)In the reasonable range of prestress,with the increase of the prestress coefficient,the ultimate load value of the top of the retaining wall is increased first and then tends to flatten.The average failure ratio of the filler is reduced and the stress state of the filler is safer with the improvement of the prestress level of the retaining wall.