PHC管桩抱箍式接头轴拔试验与精细化分析

Axial pull static load test and detail parameter analysis of PHC pipe pile with hold-hoop connection

为研究PHC(预应力高强混凝土)管桩抱箍式接头轴拔荷载下的承载性能、破坏特征及部件应力分布规律,完成了2组PHC-600-B-130管桩抱箍式接头轴拔试验,并运用有限元对试验结果进行模拟,针对三片U型抱箍卡不连续、抱箍卡开孔、端板开孔进行精细化建模,并以此进行参数分析.结果表明:接头破坏发生于桩身混凝土开裂之前,接头破坏形式为端板锚孔所在圆连续撕裂,反映了抱箍式接头传力不直接的弊端.端板破坏顺序为:先从锚孔向端板外边缘,再向附近锚孔发展.抱箍卡为:外侧“先孔间,再孔侧”;内侧“先孔侧,再孔间”.将三片抱箍卡有效连接为一个整环后,分别改善了其承载能力和变形能力约12.55%和61.63%;对于端板,建议改用Q345钢材,可提高极限承载力约32.07%,或者在端板内部加设锚固筋并加于锚孔所在圆外侧,可提高极限承载力36.04%.

In order to study the bearing capacity,failure characteristics and stress distribution of PHC(prestressed high strength concrete)pipe pile with hold-hoop connection under axial tensile load,two groups of PHC-600-B-130 pipe pile with hold-hoop connection axial tensile test were completed,and the finite element method was used to simulate the test results.The three Ushaped hoop discontinuous,hoop opening,end plate opening were modeled and analyzed.The results show that the failure of the connection occurs before the concrete cracking of the pile,and the failure characteristic of the connection is the continuous tearing of the circle where the end plate screw hole is located,which reflects the disadvantage that the force transmission of the hold-hoop connection is not direct.The failure order of the end plate is from the screw hole to the outer edge of the end plate and to the nearby screw hole.The damage rule of the outer side of the hoop is first destroyed between the openings,and then develops to both sides of the opening,while the inner side is the opposite,which is first destroyed on both sides,and then between the openings.After the three hoop cards are effectively connected into a whole ring,the bearing capacity and deformation capacity are improved by about 12.55%and 61.63%respectively.For the end plate,it is suggested that Q345 steel for end plates,which can increase the ultimate bearing capacity by about 32.07%,or add the anchor bar inside the end plate and add it to the outside of the circle where the bolt hole is located,which can increase the ultimate bearing capacity by 36.04%.