| A large number of loess slope projects will be encountered in the construction of infrastructure in our country.Therefore,the treatment of loess slopes is particularly important.For the engineering environment which is close to the traffic artery,short of land use and dense buildings,the slope often does not have the conditions for slope setting.As one of the main forms of supporting the slope,the pile-anchor structure has been widely used in slope treatment because of its convenient construction,strong anti-sliding ability,safety and reliability,etc.Setting a top beam on the top of the pile makes the supporting structure form a common force system,thereby improving the overall stability of the slope.Therefore,it is of great significance to study the force and deformation of the pile-anchor support system and the overall stability of the slope considering the effect of the top beam.In this paper,the stress deformation and stability of pile-anchor support system are calculated,taking the effect of top beam as the research object.Based on the pile-anchor supporting slope project in Lanzhou Port Area,the stress deformation and overall stability of pile-anchor supporting slope considering the effect of top beam are studied by combining field monitoring test with finite element numerical analysis,and analyzes the influence of pile diameter,pile spacing,top beam size,bolt vertical spacing and bolt row number on the bending moment and horizontal displacement of supporting pile.The main research contents and achievements are as follows:(1)Firstly,based on the Winkler elastic foundation beam model,an analysis model was established based on the pr inciple of deformation coordination between the pile top and the anchor end of the pile-anchor supporting structure.Secondly,the overall structure of the supporting structure under the action of the top beam was constructed based on the Swedish strip met hod.The stability calculation model,and then the force and deformation of the pile-anchor-supported slope and the calculation method of the overall stability are given.Finally,the method in this paper and the numerical simulation of the pile-anchor-supported slope under the action of and without top beam are compared and analyzed force deformation and slope stability.The results show that the internal force distribution,displacement change and the safety factor of the overall stability of the supporti ng slope obtained by the method in this paper are basically similar to those obtained by numerical simulation.(2)Based on the pile-anchor supporting slope engineering in Lanzhou Port Area,and taking the pile-anchor supporting slope considering the role of top beam as the research object,the monitoring results of the post-pile filling process(without top beam)and the operation stage after the filling is completed and the top beam is set are studied and analyzed.The results show that after the top beam is installed,the internal force of the supporting pile is redistributed,effectively reducing the pile body force,and the effect of restraining the displacement near the top of the pile is significant.The setting of the top beam improves the overall ri gidity of the supporting structure,has a strong restraining effect on the soil near the top of the pile,and also promotes the formation of a common force system for the pile-anchor support and reduces the influence of the anchor rod on the internal force of the pile.(3)The numerical simulation of pile-anchor supporting slope with or without top beam is carried out by PLAXIS 3D finite element software,and the influence of pile diameter,pile spacing,top beam size,anchor vertical spacing and anchor row number on the bending moment and horizontal displacement of supporting pile is comparatively analyzed.The results show that the setting of the top beam effectively reduces the bending moment of the pile and the axial force of the anchor rod,which has a strong restraint effect on the soil near the top of the pile,and improves the safety and stability factor of the slope.The pile diameter and top beam size mainly affect the bending moment and displacement of the pile above the ground;the influence of pi le diameter is greater than the pile spacing;when the vertical spacing between two rows of anchors is about 3m,the working effect is best;As the number increases,the bending moment and displacement of the pile body are significantly reduced. |
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