Experimental Study On Uplift Bearing Characteristics Of Squeezed Branch Disc Pile

Squeezed branch pile is a kind of special-shaped pile with enlarged disc.The existence of enlarged disc makes its bearing capacity better than that of straight hole pile.In this paper,the laboratory small-scale model experiment of the bearing performance of squeezed branch pile is carried out.The influence of the diameter and buried depth of the expanded disc of squeezed single branch pile,the diameter combination and spacing of the expanded disc of squeezed double branch pile on the bearing characteristics of the pile is studied.Combined with the results of the model experiment,the optimal pile parameters of squeezed branch pile are further studied.(1)Based on the static load uplift experiment of single branch and disc piles with different disc diameter and depth,the effects of disc diameter and depth on the load displacement relationship,internal force composition,disc resistance composition and lateral resistance distribution characteristics of squeezed branch and disc piles are analyzed.The results show that the ultimate bearing capacity and uplift control capacity of squeezed branch pile are better than those of straight hole pile,and the squeezed branch pile belongs to friction end bearing pile;The bearing capacity and lateral resistance strength of single disc pile are better than that of straight hole pile.With the increase of disc diameter,the resistance to deformation of pile body gradually increases,and the ratio of disc diameter to pile diameter is between 2.25～2.75.Compared with the lower part of the pile,the setting of the branch and disc is more helpful to improve the ultimate bearing capacity of the pile.It is appropriate that the buried depth of the disc is between 5 and 7 times the diameter of the disc.The maximum value of the lateral resistance strength increases with the increase of the buried depth and decreases with the increase of the diameter of the disc.(2)The results of model experiments of squeezed double branch and disk piles show that the bearing capacity and lateral resistance strength of double disk piles are higher than that of single disk piles,and the lateral resistance of the upper segment of the disk is greater than that of the lower segment.With the increase of the diameter of the bearing plate and the decrease of the spacing between the two bearing plates,the ability of the pile to resist deformation is gradually enhanced.There is a sequence for the functions of the hanging wall and the footwall.After the hanging wall reaches the limit state,the footwall gradually exerts more bearing capacity.The maximum value of side resistance strength decreases with the increase of disc diameter and disc spacing.(3)The ultimate bearing capacity of all kinds of piles is determined by load straight intersection method,and the optimum parameters of pile design are obtained by linear curve fitting and column diagram analysis.The diameter of compacted single-branch disc pile is about 53 mm,and the depth of disc embedment is between 6and 7 times of disc diameter.The disc diameter combination of squeezed-expanded double-branch pile is most suitable between 60,50 mm disc diameter and 60,60 mm disc diameter combination,and the disc spacing of 1.5 times disc spacing is most suitable.Figure 66 Table 4 Reference 76...