Experimental Study on the Influence of Opening and Closing on the Penetration Characteristics of Static Pressure PHC Pipe Pile

Abstract

To monitor the pile-sinking process of high-strength prestressed concrete (PHC) pipe piles more accurately and study the variation laws of pile-pushing force, pile axial force, pile end resistance, and pile side friction resistance with penetration depth, in this study, a low-temperature sensitive fiber Bragg grating (FBG) sensor was arranged on the pile body and a soil pressure sensor was installed at the pile end. The penetration characteristics of two closed (P1, P2) and one open (P3) full-length PHC pipe piles were tested in the field. The test results showed that the pile driving force increased with increase of penetration depth of the pile body, and the pile-pushing force of P3 was less than the pile-pushing force of P1 or P2, about 33.9%-79.7% of P1 or P2. The axial force of the pile body decreased gradually with increase of penetration depth. The axial force of the pile body of P3 was less than the axial force of the pile body of P1 or P2, and the end of the pile had a value of about 59.16%-67.75% of P1 or P2. The pile end resistance was closely related to the soil layer distribution and the characteristics of the soil layer. When the pile end resistance was harder, the soil layer changes had a greater impact on P1 and P2. As the penetration depth increased, the degradation of the lateral frictional resistance of the pile was more obvious. The test results have great significance for the application of PHC pipe piles in road engineering.