岩层设承力盘的嵌岩桩抗拔静载试验及计算方法研究

为提高东南沿海桩基础抗拔承载性能，开发应用了一种新型的、在桩身嵌岩段的上侧岩层中设置双向旋扩承力盘的抗拔嵌岩桩。结合广东佛山市某工程，进行单桩竖向抗拔承载特性静载试验。试验表明，该桩抗拔性能优越，抗拔承载力大大优于抗拔直孔桩及扩底桩。基于实测数据，建立适用于该桩的极限承载力双曲线理论模型。基于Hoek-Brown岩体破坏准则及嵌岩桩单桩抗拔承载机理，提出该桩型的抗拔破坏模式，并建立相应的单桩抗拔极限承载力计算方法。该计算方法可有效反映盘下嵌岩段的岩体性质、承力盘所处岩层的岩体性质、盘角及上覆土层厚度等因素对基桩抗拔极限承载力的影响。与规范方法、现场实测的抗拔承载力计算结果对比表明，该计算方法与现场测试结果吻合度高，具有很好的应用前景。

Study on static uplifting load test and bearing capacity calculation method of rock socketed pile with bell bearing in rock stratum

To improve the uplift bearing capacity of pile foundation in southeast coastal area, a new type of uplift rock-socketed pile with a bidirectional rotary-expanding bell set in the upper rock layer of the rock-socketed segment is developed. Based on a project in Foshan city of Guangdong province, the static uplift load tests of single pile were carried out. It was observed from the tests that the kind of piles are more excellent in the uplift bearing capacity than conventional piles or belled piles. A hyperbolic model describing the ultimate bearing capacity of the type of piles is established by referring to in-situ data. On the basis of Hoek-Brown failure criterion and uplift bearing mechanism, the uplift failure mode is proposed for this rock-socked pile, and the corresponding calculation method for ultimate uplift bearing capacity is established. In the proposed calculation method, the influences of rock mass properties of rock-socketed segment under the bearing bell, rock mass properties of the rock stratum in which the bearing bell is located, the angle of bearing bell and the thickness of overlying rock layer on the ultimate uplift bearing capacity of this rock-socked pile can be reflected effectively. Compared with the results from the specification calculation method, the results from the proposed calculation method are in better agreement with the field test results, indicating its good application prospect.