Influencing Factors Analysis For The Law Of Excess Pore Water Pressure Changes On Group Of Static Sinking Pipe-pile With Holes

Pile foundation is the most common form of deep foundation,among lots of pile types,pipe-pile is widely used because of its superiority.However,there are many factors that affect the variation of excess pore water pressure while sinking pile,therefore,many experts and scholars have also regarded it as a major difficulty in the study of pipe-pile.Based on single pipe-pile with holes,and on the basis of previous studies on the soil effect of static pressure single pile-pile with holes,the influence factors of excess pore water pressure in sinking process of group piles are explored.First of all,different base pile spacing is derived by using the theoretical formula,the relationship between the maximum pore water pressure and the radial distance,the rate of the sinking pile,the opening aperture and the depth of the pile,and the influence of the construction sequence,the interval of construction,the way of opening and the number of piles on the excess pore water pressure of group piles is analyzed.Then through theoretical calculation,the relationship curve between excess pore water pressure and its influencing factors is calculated and plotted;finally,numerical simulation is used to simulate the piles sinking process,and the numerical simulation curves between the piles and various factors are obtained,and compared with the theoretical change curve.The results are as follows:(1)The relationship between the excess pore water pressure and its influencing factors is deduced based on the excess pore water pressure formula of single pipe-pile with holes.Similar to the single pipe-pile with holes,other parameters are constant,the maximum excess pore water pressure is inversely proportional to the radial distance,proportional to the rate of the sinking pile,inversely proportional to the aperture,proportional to the depth.(2)Different from single pile,the influence factors of group piles excess pore water pressure also include pile spacing,construction sequence and the interval of construction.The greater the spacing of the pile,the smaller the excess pore water pressure value,the more the pile number of the pile group,the greater the maximum value of the excess pore water pressure is reached;the maximum value of the excess pore water pressure superposition of the pile group can be effectively reduced by adopting the interval jump method,setting the optimal hole opening mode,andcontrolling the reasonable pile-breaking interval.(3)Through theoretical calculation,the relationship curve between excess pore water pressure and its influencing factors is calculated and plotted,analysis curve can be obtained: The change rule is basically consistent with the theoretical formula,moreover,the excess pore water pressure value of group piles in plastic zone is much higher than that in elastic zone.(4)Using ABAQUS to simulate the sinking process of group piles,numerical simulation curve is drawn between the excess pore water pressure and each factor of perforated pipe-pile group with holes,through the comparison with the theoretical change curve,the change trend of the two curves is basically consistent,which verifies the correctness of the theoretical formula.