Study On Working Characteristics On Thick Soft Clay Reinforcement Of Variable Cross-section Pipe Pile Under Embankment Load

Relying on the tutor’s scientific research project, indoor model test and FLAC3 D numerical simulation analysis method, working characteristics on thick soft clay reinforcement under the embankment load of variable cross-section pipe-pile have been researched. The key problems such as bearing capacity between ladder-type variable cross-section pipe-pile and constant section pipe-pile are comparatively analysed. The advantages of the ladder-type variable cross-section pipe-pile composite foundation have been summarized. Following works are focused on this dissertation:1.Based on indoor large scale model experiments under the embankment load of ladder-type variable cross-section pipe-pile and constant section pipe-pile composite foundation test results, the differences of pile top and pile soil load-settlement, pile shaft force,pile-soil load share ratio, pile-soil stress ratio and pile side friction have been studied. The advantages of thick soft clay reinforcement on variable cross-section pipe-pile have been summarized.2.Based on FLAC3 D,the finite difference model of the composite foundation is established, the influences of joint position of upper and lower pipe pile section and pipe pile diameter ratio to the bearing capacity of composite foundation have been studied. The influences of the cushion modulus and thickness to the bearing capacity of composite foundation have been discussed.The results show that: Under the same load, the pile-soil stress ratio and side friction of ladder-type variable cross-section pipe-pile are much greater than those of constant section pipe-pile. The bearing capacity of ladder-type variable cross-section pipe-pile is much greater than that of constant section pipe-pile. The reasonable choices of diameter ratio of upper and lower pipe pile can effectively improve the bearing capacity of ladder-type variable cross-section pile-pile composite foundation. The reasonable choices of cushion modulus and cushion thickness can effectively improve the bearing capacity of ladder-type variablecross-section pile-pile composite foundation.