Study On The Action Mechanism And Design Theory Of Vertical Prestressed Buttress

Retaining walls in urban areas often have insufficient space in front of the wall,and it is not easy to carry out anchoring works in front of the wall.At present,it is difficult to reinforce such unstable retaining walls.Based on this,this article proposes a vertical prestressed anchor cable and gravity type pier composite retaining wall reinforcement structure,that is,vertical prestressed buttress.The structure uses the anchoring force of the anchor cable to increase the stability of the pier and thus improve the resistance of the pier to the existing retaining structure.The vertical anchoring force compensates the gravity of the pier to reduce the masonry size of the pier and effectively solve the problem The problem of insufficient reinforcement space in front of retaining walls in urban areas has been addressed.In this paper,the theoretical derivation,numerical simulation and indoor model test are used as research methods to analyze the mechanical mechanism of existing retaining walls and vertical prestressed piled buttress.The main work and conclusions made are as follows:(1)Three-dimensional finite element modeling and calculation analysis of vertical prestressed piled pier,the results show that: the addition of vertical prestressed piled pier outside the wall can effectively limit the deformation of the retaining wall;The earth pressure distribution on the back of the wall does not change much;in the process of simulating the earth pressure gradually increasing,the resistance distribution form of the pier to the existing retaining wall has not changed much,both are the largest at the top of the pier,and linearly decrease to the middle of the pier From small to zero,it is distributed in triangles.After calculation and analysis,the combined force acting point of the supporting force of the pier is about 5/6 of the pier height above the pier bottom.It is reasonable to design the reinforcement according to this height;when the earth pressure is small,the pier is at The tendency of the anchor cable to tilt toward the inside of the retaining wall under the action of the eccentric moment of the anchor.After the earth pressure becomes larger,the pier will overturn or slide together with the retaining wall;(2)Simplify the three-dimensional finite element model to two-dimension and analyze the parameters of the vertical prestressed piled pier.The calculation results show that increasing the base width of the pier,increasing the prestress or eccentricity of the anchor cable can effectively limit The deformation of the existing retaining wall,because the increase of these three will lead to the increase of the anti-sliding force or anti-overturning moment of the pier,thereby increasing the resistance of the pier to the existing retaining wall;as the relative height of the pier The horizontal displacement of the top of the wall gradually decreases.When the support pier reaches a certain height(about 2/3 of the wall height),it will continue to increase the height,and the improvement of its reinforcement capacity is limited;(3)Based on the limit equilibrium method,the maximum horizontal resistance Fh generated by the pier against the retaining wall is analyzed,the maximum horizontal resistance Fhc generated by the pier based on the anti-slip stability is derived,and the maximum level generated by the pier based on the anti-overturning stability is derived Resistance Fho,the maximum resistance Fhp generated by the support pier based on the foundation bearing capacity control index is derived,and the influence of the structural parameters of the vertical prestressed stacked support pier on the resistance of the support pier is analyzed;(4)Carry out the indoor model test of the vertical model prestressed piled pier,and calculate the maximum horizontal resistance Fhc,Fho and Fhp based on the anti-sliding stability,anti-overturning stability and foundation bearing capacity control indicators of the pier respectively The formula was verified;the effect of the vertical anchor cable on the stability of the pier was verified;the coupling law of the anchoring force of the cable and the bearing capacity of the foundation to the resistance of the pier was also consistent with the theoretical analysis;(5)Based on the above research results,the practical application of the new structure is calculated and analyzed.The results show that the structure has a significant reinforcement effect,and has been in a stable state for many years of operation,and the reinforcement effect is good.