超长大直径变截面钢管复合桩竖向承载力算法

变截面钢管复合桩的受力性能较好,在工程中应用较多,但是其理论研究却较为滞后。对该桩型竖向承载力计算方法进行研究,分析了其荷载传递规律,选取桩基受力极限状态,考虑钢管作用与变截面处承载力,利用桩土位移协调关系推导了超长大直径变截面钢管复合桩竖向极限承载力计算公式,并用该方法和现行规范计算方法对鱼山大桥37号桩基进行竖向承载力计算,与试桩自平衡试验实测值进行对比。研究结果表明:试桩自平衡试验曲线平缓无陡降,单桩竖向极限承载力试验值为120 056 kN,利用现行规范公式计算值与实测值相比偏差过大,而本文推导方法计算结果与实测值较为接近,验证了本文方法的可靠性。

Calculation Method of Vertical Bearing Capacity of Super-Long,Large-Diameter and Step Tapered Composite Steel Pile

Step tapered steel composite piles have excellent mechanical performance and they are widely used in engineering, but the related theoretical research is lagging behind. The calculation method of the vertical bearing capacity of the pile type was studied, and the load transfer rules were analyzed. The limit state of the pile foundation was analyzed. Considering the action of the steel tube and the bearing capacity at the stepped cross section, the vertical ultimate bearing capacity calculation formula of the super-long and large-diameter steel tube composite pile with stepped cross-section was derived by using the coordination relationship between the pile and soil displacement. The vertical bearing capacity of No. 37 pile foundation of Yushan Bridge was calculated by using this method and the calculation method in the current standard, which were compared with the measured value in the self-balancing test of the test pile. The results show that the self-balancing test curve of the test pile is smooth and without mutation. Besides, the bearing capacity of single pile is 120 056 kN. Moreover, the deviation between the calculated value of the current standard formula and the measured value is too large, while the calculated value by using the method in this paper is close to the measured value, which verifies the reliability of the method in this paper.