Effect of cemented soil properties on the behavior of pre-bored grouted planted nodular piles under compression

Abstract

A series of unconfined compressive strength tests of cemented soil and a model test of a pre-bored grouted planted nodular (PGPN) pile were conducted to investigate the effect of cemented soil properties on the behavior of PGPN piles under compression. The load-displacement response, axial force, and tip resistance were measured during the loading process. Several conclusions could be drawn by comparing the results of the present model test with those of a previous test: the compressive bearing capacity of the PGPN pile was enhanced by increasing the cemented soil strength; the ultimate skin friction of the PGPN pile was increased to 1.06–1.36 times when the strength of the cemented soil along the pile shaft increased from 0.706 MPa to 1.21 MPa; the ultimate mobilized base load was increased to 1.42 times when the strength of the cemented soil at the enlarged base increased from 11.10 MPa to 16.02 MPa.

中文概要

目的

静钻根植竹节桩是一种由预制竹节桩和水泥土组 成的组合桩基。通过一系列水泥土试块的无侧限 抗压强度试验和静钻根植竹节桩的单桩模型试 验,研究水泥土性质对静钻根植竹节桩抗压承载 性能的影响。得出水泥土强度的提高对静钻根植 竹节桩桩侧和桩端承载性能的影响规律,为静钻 根植竹节桩的设计和推广应用提供理论依据。

创新点

1. 得出静钻根植竹节桩桩端扩大头中水泥土强度 的提高对其桩端承载性能的影响规律;2. 得到静 钻根植竹节桩桩周水泥土强度的提高对其桩侧 摩擦性能的影响规律。

方法

1. 通过改变静钻根植竹节桩桩端扩大头的水泥土 强度的模型试验,得到桩端水泥土强度的提高对 桩基桩端承载性能的影响规律;2. 通过桩周水泥 土强度不同的静钻根植竹节桩的模型试验,得出 静钻根植竹节桩桩周水泥土强度的提高对其桩 侧摩擦性能的影响规律。

结论

1. 提高水泥土强度能够改善静钻根植竹节桩的抗 压承载性能;当桩周水泥土强度从0.706 MPa增加 到1.21 MPa,桩端水泥土强度从11.10 MPa增加到 16.02 MPa时,静钻根植竹节桩极限抗压承载力提 高了36%。 2. 当桩周水泥土强度从0.706 MPa增加 到1.21 MPa时,不同深度土层中桩侧极限摩阻力 增加到1.06–1.36倍。3. 桩端水泥土强度从 11.10 MPa增加到16.02 MPa时,静钻根植竹节桩 的极限桩端承载力增加到1.42倍。4. 在静钻根植 竹节桩的实际工程应用中,增加桩端扩大头处水 泥土强度能够有效提高桩基的承载性能,而桩周 水泥土强度的增加对桩基侧摩阻力的提高效果 不明显。