Experimental Study On Vertical Bearing Behavior Of Prestressed Concrete Pile In Not-weak Soil Layer

Prestressed concrete Pile is widely applied, its dosage is big, Experimental study on the vertical bearing behavior have huge social meaning. The determination of the vertical bearing capacity of the prestressed concrete piles is hot topic, but it is difficult. Academic circles devoted a lot of vigor in studying on the vertical bearing behavior. at present, there are only a few empirical formulas about the calculation of the vertical bearing capacity of the piles and there is no leading method in China, If the results of the bearing capacity are determined based on the empirical formulas of the current design code, it will be much lower than that based on the test, the vertical bearing behavior is not full applied, the cost of the engineer increase. In the paper,we study the theory of the vertical bearing behavior, after comparing various calculating method of the vertical bearing capacity between different code, the key of the capacity design is how to determine the pile shaft resistance and the toe resistance, at present, the pile shaft resistance and the toe resistance in the code was determined by the experience between the physical index sign to the bearing capacity or few test, the result is inconsistent comparing with the actual bearing capacity of the pile,the calculating result of the code is conservative. If we determine the bearing parameter by testing, the result will be actual. This paper research the theory and principle of the various testing method, after discussing the advantage weakness and applicability, we give some suggestion about the study of the vertical bearing behavior.Based on theoretical analysis,this paper discuss the test between the dynamic testing and the static load testing, after discussing the accuracy of the dynamic result, we prove that the dynamic testing can be used to study the vertical bearing behavior of the pile, the contents is how to determine the pile shaft resistance and the toe resistance. Combining the test experience in SHUNDE, this paper choose the result of 30 piles in 10 workplaces in 3 kinds of geology(graveiiy soil, completely weathered rock, highly weathered rock), the test method is the dynamic testing, we acquire the parameter of the pile shaft resistance and the toe resistance by CAPWAP method and obtain native database data in SHUNDE.Comparing the test result with the geotechnical investigation report and GUANGDONG Specification for prestressed concrete pile, we found the difference of the result by using 3 methods,this paper give the modify suggestion about the pile shaft resistance and the toe resistance. This paper give the design suggestion of the 10 typical geology section of 3 kinds of geology in SHUNDE. It provided reference to the engineering and it have huge actual meaning.