Experimental Study On The Vertical Bearing Capacity Of The Composite Piles Of High Pressure Bored Concrete Precast Pipe

The composite piles of high pressure bored concrete precast pipe are a product of the development of civil engineering in China which also is a new type of pile by researching and improvement. The piling technology of the composite piles of high pressure bored precast concrete pipe was acquired by researching the piling technology of the high pressure bored piles and the concrete precast pipe piles and combining the method with requirements of construction. The composite piles of high pressure bored concrete precast pipe has advantages including low influence to surrounding、high bearing capacity、economic benefits and widely application etc and it could be applied in engineering.According the empirical formula of the current codes to estimating standard values of the ultimate vertical bearing capacity of single pile of the composite piles of high pressure bored precast concrete pipe is much lower than the actual standard values of the ultimate vertical bearing capacity were acquired by the pile dead load test. Then the bearing capacity of single pile is low and the project cost would be wasted and the high bearing capacity of the composite piles of high pressure bored precast concrete pipe could not be highlighted are inevitable. The designing institutions is not related to the reference and technical discipline for the application of the composite piles and the lower cost of the bearing capacity of single pile, also their research of the composite piles is still at an early stage.In this paper11composite piles of high pressure bored concrete precast pipe had been tested by dead load, then the pile dead load test data and the geological survey report was analysed with discussing the influence rule to standard values of the ultimate vertical bearing capacity of single pile when the pile body entered into the clay、fine sand、medium sand respectively and the pile tip entered into the fine sand、medium sand respectively. So the empirical formula of the ultimate vertical bearing capacity standard values of single pile in technical code for building pile foundations could be revised, then the ultimate vertical bearing capacity standard values of single composite pile of high pressure bored concrete precast pipe could be obtained. It is obviously that the estimated ultimate vertical bearing capacity standard values of single composite pile is much more close to the bearing capacity of the piles by comparing the calculated values with the experimental values, then the actual force situation was respond extremely and the suitability of estimation formula was validated. In conclusion, the research achievement have play a certain guiding role for pile design and construction and was significant meaningful to application for the new type of pile foundation.