Abstract: In order to investigate the variation of pile end resistance with penetration depth in silt and silty clay, a spoke pressure sensor was installed at the pile end of the test pile P1, and a fiber grating sensor was installed at the test pile P1 and P2 200 mm away from the pile end. Two different test techniques were used to monitor the pile end resistance during the on-site penetration of two closed-end prestressed high-strength concrete pipe piles. The test results show that the resistance of the pile end is closely related to the change of the soil layer. The harder the soil layer is, the greater the resistance of the pile end is. When the pile end enters the silt layer from the silty clay layer, the pile end resistance increases significantly. The pile end resistance in the silt reaches twice of that of the silty clay layer. During the whole penetration process, due to the difference of soil layers at different locations, there is a certain difference between the pile end resistance of P1 and P2. The position difference of the same soil layer has a great influence on the pile end resistance. Below the ground 1.50 m, the difference of pile end resistance between P1 and P2 reached 89.29 kN; While below the ground 3.50-4.50 m, the difference between the pile end resistances of the two piles is small.

Key words: static pressure pile, spoke pressure sensor, FBG sensor, pile end resistance, field test