Uplift failure of drilled and post-grouted concrete pile
The drilled and post-grouted concrete pile,combining the advantages of bored piles and prestressed pipe piles,presents a novel foundation solution.It can solve the problems such as unreliable quality of pile body of grouted pile and difficulty in sinking prestressed pipe pile.CT scans were performed for the uplift test of buried post-pressure pipe piles.CT scan images of model piles under different displacement states were obtained to visually reveal the damage surface development and to establish the damage surface equation.The damage surface equation of the pullout resistant pile proposed by other scholars was optimized,the uplift limit bearing capacity function of drilled and post-grouted concrete pile corresponding to the damage surface was optimized through the static equilibrium equation,and the parameters of the optimized damage surface equation were determined by using genetic algorithm.The accuracy advantage of the resulting damage surface equation was verified by comparing multiple theoretical assumed damage surface with the experimentally obtained damage surface.The findings are as follows:the damage of drilled and post-grouted concrete pile occurs when the uplift displacement reaches 4.5 mm;and when the grout layer and the soil are tightly bonded and no obvious displacement occurs between the two,the damage only occurs in the soil around the pile outside the grout layer.The damage surface extends from the bottom of the pile to the top of the pile,i.e.,the closer to the top of the pile,the farther the damage surface is from the pile body.The damage surface is tangential to the concrete sidewall at the bottom of the pile,and the angle between the ground and the horizontal plane is close to 42° with a flared damage.The theory in this paper assumed that the correlation coefficient of R2=0.97 between the damage surface and the experimentally obtained damage surface,whereas the previous theory assumed the correlation coefficient of R2=0.91 between the damage surface and the experimentally obtained damage surface.The damage surface equation in this paper was closer to the experimentally obtained damage surface.The research results have important reference value for the design calculation of drilled and post-grouted concrete pile.
railroad power projectdrilled and post-grouted concrete pileCT scandamage surfaceuplift capacitygenetic algorithm
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