Numerical Simulation Of Bearing Character Of Bored Pile By Post-Grouting In CCTV New Building

Bored pile is a chief type of foundations used in bridges and high-rise buildings. But some drawbacks such as sedimentation on the bottom of the pile and mud around the pile shaft arise from traditional construction technology of bored pile, which causes obvious decrease of end-bearing capacity and side frictional force. Post-grouting can improve the drawbacks and strongly increase the bearing capacity of pile. In this way, it's valuable and meaningful to do the research on the load-bearing theory of post-grouting pile. Unfortunately, the study based on in-situ test is not so satisfactory. For the position of testing points and the number of measuring instruments are limited, data are not enough and may exist error. It's necessary to adopt a method which is adaptable to simulate nonlinear, inhomogeneous medium and provides complex boundary elements.Based on the construction of CCTV new building, this paper carries on analytical research on bearing character of grouting pile by means of FLAC^3D software based on fast lagrangian analysis, compares the displacement, distribution of axial force and frictional force along the pile shaft under the circumstance of no grouting, grouting on side, grouting on the bottom and grouting on both side and bottom.According to the result, the ultimate bearing capacity is much higher in grouting pile than ordinary bored pile. The improvement is limited in side-grouting pile, for about 19.37%, while there are far more improvements in bottom-grouting pile and both side and bottom grouting pile, for more than 93.79%. With grouting on the bottom, the bearing character of pile becomes better, which can be seen from the figures of Q-s curves that change from abrupt drop into gradual fall. It does not only improve the end-bearing capacity and increase the ratio of end-bearing capacity in ultimate bearing capacity, but also enhance the side frictional force, during which the friction pile changes into friction and end-bearing pile. The end force also takes part in load-bearing progress in advance. When load is slight, end force affords most parts of the load. During the increase of load, side-frictional force acts from the top to the bottom, and increases to maximum。...