Numerical Simulation Analysis Of Bearing Characteristics Of Three PHC Pipe Piles Under Horizontal Load

PHC pipe piles are widely used in high,medium and low-rise buildings,highways,railways,bridges,ports,wharves and other low-cap foundations due to their high single pile bearing capacity,factory standardized production,and controllable construction quality.Practice has shown that PHC pipe piles can be well applied to pile foundations that are mainly subjected to larger vertical loads,and can have good engineering performance in pile foundations that are mainly subjected to larger horizontal loads.Restricted by conditions such as the engineering site,there are more studies on the single pile and double-pile foundations of PHC pipe piles that are subjected to relatively large horizontal loads in the engineering community,and fewer studies on the pile groups above the three-pile level.Based on previous field test studies on the horizontal bearing characteristics of the PHC pipe pile three-pile foundation,this paper considers the pile-soil interaction and uses the finite element numerical simulation method to study the horizontal bearing characteristics of the PHC pipe pile three-pile group pile foundation.The main contents of the research are as follows:(1)Under the same working conditions,the critical horizontal load and ultimate horizontal load of the in-line three-pile group are greater than those of the triangular three-pile group.The former are 1.3 times and 1.08 times that of the latter,respectively.(2)Under the ultimate horizontal load,the stress state of the anchoring steel members of the two three-pile group piles did not reach yield.(3)Under the same load,the maximum bending moment of the in-line three-pile group pile is obtained at the top of the front pile,and the internal force shared by the front piles is greater than the rear pile;the triangle three-pile group has the largest pile body The bending moment is obtained at about 1/6 to 1/5 of the pile’s length from the top of the pile,and the internal force shared by the front piles is smaller than the rear piles.(4)Under the same load,with the increase of the depth of the pile top,the maximum bending moment of the two three-pile group piles gradually decreases,and the maximum shear force of the pile is obtained at the connection between the pile and the cap,and Are gradually reduced,so the pile groups are less susceptible to bending damage.(5)Under the same load,with the increase of pile spacing,the maximum bending moment,maximum shear force,and maximum horizontal displacement of the foundation piles of the two three-pile group piles gradually decrease,and the pile groups are less prone to bending failure.(6)Under the same load,with the increase of the pile length,the maximum bending moment and maximum horizontal displacement of the two three-pile group piles gradually decrease,and the pile group piles are less prone to bending failure.(7)Under the same load,with the increase of the pile side soil modulus and internal friction angle,the maximum bending moment and maximum horizontal displacement of the two three-pile group piles gradually decrease,making the group piles more difficult.Bending failure occurred.(8)Under the same load,when the pile spacing is 3 to 4 times the pile diameter or the pile length is 16.7 to 21.7 times the pile diameter,the comprehensive effect coefficients of the two three-pile group piles are larger,and the pile group effect is more obvious.With the increase of pile spacing and pile length,the comprehensive effect coefficients of the two types of three-pile group piles gradually decrease,and the pile group effect is weakened.