The pre-bored grouted planted (PGP) pile is a composite pile consisting of a precast concrete pile and the cemented soil around the pile. Thus, the PGP pile shaft capacity is affected by the pile–cemented soil interface and the strength of the cemented soil formed around the pile. In this paper, a series of shear tests were conducted to investigate the frictional capacity of the precast concrete pile–cemented soil interface, and the strength of cemented soil and its effect on the interface frictional capacity. The test results show that the frictional capacity of precast pipe pile–cemented soil interface is largely dependent on the cemented soil strength, and the peak skin friction of the interface increases from 7.58 to 204 kPa with the cemented soil strength increasing from 65 to 1500 kPa. An adhesion factor is proposed to correlate the peak skin friction of the precast pipe pile–cemented soil interface and cemented soil strength. The adhesion factor is found to range from 0.116 to 0.141 corresponding to the range of cemented soil strength from 65 to 1500 kPa. It was also noted the failure at the pile–cemented soil interface is brittle. The scale effect also exists in the pile–cemented soil interface shear test, and the scale effect factor is 1.9 when the pile diameter decreases from 85 to 37 mm. Accordingly, the design of PGP pile should avoid approaching the frictional capacity of the pile–cemented soil interface.

预钻孔灌浆植桩（PGP）是一种复合桩，由预制混凝土桩和桩周围的水泥土组成。因此，PGP桩的竖井容量受桩-水泥土界面和桩周围形成的水泥土强度的影响。本文进行了一系列的剪切试验，以研究预制混凝土桩-水泥土界面的摩擦能力，以及水泥土的强度及其对界面摩擦能力的影响。测试结果表明，预制管桩-水泥土界面的摩擦能力在很大程度上取决于水泥土的强度，该界面的最大表皮摩擦力从7.58增加到204 kPa，水泥土强度从65增加到1500 kPa。 。提出了一种附着因子，以将预制管桩-水泥土界面的峰值皮肤摩擦与水泥土强度相关联。发现粘附因子在0.116至0.141的范围内，对应于水泥土强度在65至1500kPa的范围。还应注意，桩-水泥土界面处的破坏很脆弱。桩-水泥土界面剪切试验中也存在尺度效应，当桩直径从85 mm减小到37 mm时，尺度效应因子为1.9。因此，PGP桩的设计应避免接近桩-水泥土界面的摩擦能力。还应注意，桩-水泥土界面处的破坏很脆弱。桩-水泥土界面剪切试验中也存在尺度效应，当桩直径从85 mm减小到37 mm时，尺度效应因子为1.9。因此，PGP桩的设计应避免接近桩-水泥土界面的摩擦能力。还应注意，桩-水泥土界面处的破坏很脆弱。桩-水泥土界面剪切试验中也存在尺度效应，当桩直径从85 mm减小到37 mm时，尺度效应因子为1.9。因此，PGP桩的设计应避免接近桩-水泥土界面的摩擦能力。