The Mechanism And Deformation Research On Retaining Structure With Long-short Pile Combination

Retaining structure of foundation pit was designed in the form of equal-length pile.The length of pile was designed to meet the stability of uplift,the overall stability,the seepage stability,the overturning stability and the inlay stability.Retaining structure with long-short pile combination will multiply the retaining effects of short pile and transfer the earth pressure to long pile through the crown beam.It can ensure the overall stability of the foundation pit.Long piles bear greater bending moments and play a role in binding bearing capacity for the improvement of counter bend point position.Retaining structure with long-short pile combination has an absolute advantage in the design of bracing of the foundation pit.Model test and ABAQUS three-dimensional contains finite element and analysis methods of the retaining structure with long-short pile combination.They were used to research mechanism of structure,deformation of the retaining structure.Set up long-short piles retaining structure model,Training gauge was installed on both sides of the pile.According to the strain and displacement data of the long-short piles retaining structure in the process of excavation and the regulation of bending moment and displacement in the excavation of foundation pit,its Investigating influences of different the short pile ratio of long-short pile retaining structure,the different pile-length of long-short pile retaining structure.Combined engineering practice to integrate and analysis of test data.In order to make a deeply comprehensive study of three dimensional working mechanism of combination of long-short pile retaining structure,we set up three-dimensional analysis model to analysis influence of different the short piles ratio of long-short pile retaining structure,different pilelength of long-short pile retaining structure.The conclusions of the study include:(1)Under the condition of short pile ratio,the increase of short piles will result the increase of bending moment of long piles and short piles.The maximum bending moment has the increase of long pile faster than short piles.The increase of short pile which long pile is near the bottom of the short pile.The long pile bending moment will increase obviously.With the increase of the excavation depth,the long-short piles bear a greater bending moment.(2)With length decrease of short piles,long piles endured larger bending moment,and the maximum bending moment increases of long piles faster than short piles.The maximal bending moment of long piles and short piles increase slightly,the displacement of long-short piles retaining structure will increase because of the length decrease of short piles.(3)When the long-short piles were used as the retaining structure of foundation pit,the length of piles and the number of short piles will have the obvious influence on the bending moment,and slight influence on horizontal displacement.Therefore,the bending moment is the primary control index to design the combination of long-short piles retaining structure.