大直径超长嵌岩桩承载特性分析

Bearing characteristics of super-long rock-socketed pile with large diameter

大直径超长嵌岩桩在工程中应用广泛,但其荷载传递机理和承载能力特性的研究仍不够深入。针对现有现场试验研究和数值分析的不足,基于马来西亚槟城二桥工程,对大直径超长嵌岩桩承载特性进行数值模拟和现场试验研究。通过对比发现,有限元计算结果与自平衡法的实测数据有较好的吻合性,但由于土动摩阻和孔隙水压力影响,静动法测试结果比自平衡法大30%左右。大直径超长嵌岩桩侧摩阻力从上而下逐步发挥,且沿深度非线性分布现象明显。实际总的桩侧摩阻力占荷载90%,远小于桩土极限侧摩阻力。

The super-long rock-socketed pile with large diameter is widely used, but the bearing characteristics and load transfer mechanism is not totally figured out. Aiming at the shortcomings of the existing field test research and numerical analysis, we carried out a case study and numerical analysis of super-long rock-socketed pile based on the Penang second bridge project in Malaysia. An elaborate numerical model was established to study the bearing characteristics of super-long rock-socketed pile with large diameter. The comparison of field test and numerical analysis indicates that the finite element calculation has good agreement with the results of O-cell test, but the bearing capacity by statnamic test is 30% larger than that of O-cell method because of the influence of soil dynamic friction resistance and pore water pressure. The side friction of pile accounts for 90% of the total load. The friction of pile develops gradually from the top to the bottom and distributes nonlinearly along the pile. The actual total side friction is far less than the designed ultimate side friction.