基于孔扩张理论的螺旋桩抗拔承载力计算分析

Theoretical computation of the uplift bearing capacity of helical piles based on cavity expansion method

螺旋桩以其施工方便快捷、承载力好等技术优点在输电线路、光伏支架等工程基础中广泛使用;然而,既有螺旋桩抗拔承载力理论计算方法的误差仍相对较大。基于圆孔扩张理论,采用Tresca屈服准则修正了螺旋桩抗拔承载力计算方法;开展了砂土地基中螺旋桩抗拔承载力原型足尺试验,实测了不同类型螺旋桩的荷载-位移关系曲线,分析了其抗拔极限承载力;通过试验结果和既有文献实测数据的对比分析,验证了理论计算方法的准确性和可靠性。研究结果表明,锚盘的抗拔承载力系数随着首叶埋深的增大而变大,其上限值主要受土体的刚性指数约束;提出的螺旋桩抗拔极限承载力理论计算方法较传统计算方法精度有所提高,计算误差约为10%。

Helical piles are widely used in power transmission lines and photovoltaic engineering.It has many advantages,such as convenient construction,large bearing capacity,etc.However,the precision of the existing theoretical calculation method for estimating the uplift bearing capacity of the helical pile is still not satisfying.Based on the cavity expansion method,through the Tresca criterion,a modified approach to estimate the uplift bearing capacity of the helical pile was proposed.Full-scale model tests on the uplift bearing capacity of helical piles were carried out,and the tensile load-displacement response was measured.The uplift bearing capacity of the helical piles tested was obtained with consideration of different failure interpretations.Based on the comparison between the predicted uplift bearing capacity of the helical piles using the method proposed in this paper and the results obtained from the literature,the accuracy and reliability of the theoretical calculation method herein are verified.The results show that the uplift bearing capacity coefficient of the helical anchor increases with the increase of the buried depth of the first helix,and its upper limit value is mainly restricted by the rigidity index of the soil.Compared with traditional calculation methods,the theoretical calculation method in this paper is more accurate,which has about 10%calculation error.