Numerical Simulation And Theoretical Analysis On The Depth Emebdded In The Pile Caps Of PHC Pipe Pile

With the development of reform opening up and economic construction，the PHC pipepiles have been introduced into china in the late1980s，This kind of pile foundation has beenwidely used in engineering constructions due to its advantages such as high capacity，widedesign selection range，economics，easy to transport lifting，and faster construction．Today，the PHC pipe pile has been used in many projects which ask the pile to withstand horizontalloads，so the research about deformation and the stress distribution of the PHC pipe pilesunder horizontal loads is of particularly important．The past studies were mainly throughlaboratory tests and theoretical analysis，getting a lot of valuable experimental data andtheoretical analysis results．however the stress concentration due to the size of the connectionsection of pile and pile cap is takes place and the level of the sudden dimensional change atshear and the moment in here at maximum．Therefore，the head of the pile is easy todamage．In the present，the main method used in site is to strengthen the head of pile bychangens the filling material，so further study is of theoretical and practical importance．In this study，two jobs were done．First，numerical simulate analysis are conducted onsingle PHC pipe pile with cap under a cycle horizontal load，in which the PHC pipe pile isfilled with concrete core in the head of pile，and the depth embedden in the pile cap arechanged．Second，a theory calculating formula is set up，which can be used to calculate theultimate flexural capacity．The conclusions are drawn out as follows：（1）Through the quasi-static simulation，The loading-displacement hysteretic curves ofordinary fill core PHC pipe pile with different embedded depth into the cap under cyclehorizontal loads are obtained．（2）When the depth embeded into the cap is less than1/2pile diameter，a good ductilityduring the process of stress was showed and the anchor bars for the embedded pile caps of pile head play its full role．Anchor reinforcement of resistance is a huge part of the ultimatebearing capacity when the specimen to ultimate load．The ductility of the specimen recededwith embedded depth increasing and the effect of anchoring bar is also retrograded，to a largeextent.（3）The ultimate bearing capacity specimen is no longer increased with the embeddeddepth increasing，which can be attributed to the insufficient rigidity of the pipe pile result inthe destruction of the pipe．Then comparing this specimen and the ordinary fill core PHC pipepile，it can be found that the specimens bearing capacity is reduced in the present study，however，the ductility is better than the rigid structure of ordinary fill core PHC pipe pile．（4）Referring to the theoretical approaches of ultimate bearing capacity of filling corepiles and pile cap connection node，the calculation formula for flexural capacity of the corefilling pile was proposed．Additionally，the mechanical model of connection joint between thePHC pile and pile cap was simplify calculated targeted，combining with finite elementanalysis software，the formula was also validated and defined the scope of the formulaapplication．...