Vertical Compressive Bearing And One Dimension Wave Characteristics Of Static Drill Rooted Pile

The static drill rooted pile, as a new composite pile foundation, needs drilling and mixing cement soil first before inserting the precast pile. The precast pile is characterized with equidistant bulge along the length direction. Static drill and rooted pile is widely used for many advantages and the corresponding technologies such settlement calculation, dynamic testing are also urgent to be improved.1. The analytical formula of calculating single static drill rooted pile settlement is derivated in this paper based on the load transfer method, geometry and craftsmanship characteristics of pile. Determination method of related formula parameters is also suggested. By comparing the calculated results with actual load settlement curve, we prove the rationality of formula.2. The load settlement curve of static drill rooted pile is simulated by ABAQUS and its trend is consistent with measured result. In this paper, we described the load transfer mechanism detailedly from distribution the axial stress, pile settlement, shear stress distribution of concrete-cement soil interface and cement soil-natural soil interface. The static drill rooted pile is a typical friction pile and we found that the cement soil-natural soil interface is generally destroyed prior the pile-soil cement interface. Based on analysis factors such as pile diameter, thickness of pile lining, cement soil strength, thickness of cement soil, bulge depth, bulge spacing, friction coefficient between cement soil and soil affect on bearing capacity influence, we presents a general method to improve the ultimate bearing of pile.3. In order to find out the dynamic testing characteristics of PHDC pile, its testing curve is compared with traditional PHC curve of pile. All these curves are obtained by ABAQUS dynamic simulation. We found that the bulge would delay the reflection time of defect, pile bottom and enhance the amplitude of vibration curve. Then, the effect of bulge depth, bulge spacing, thickness of pile lining, bulge shape, crack length and width on the test curve’s characteristic parameters such as reflection time and amplitude are discussed. Finally, we analyzed the reducing coupling and the delayed effects of reflection caused by static drill rooted pile’s connection and gave a reasonable explanation and suggestion.