大直径钻孔灌注桩承载力试验研究

以某大直径桩基础工程为例，进行了5根Ф1500mm试桩的竖向与水平静裁荷试验，实测得到了桩的荷载．沉降曲线、不同桩身截面的轴力、水平力．位移．时程曲线、水平力位移梯度关系、临界承载力以及地基土水平抗力系数，探讨了大直径钻孔灌注桩的竖向荷载传递机理和水平荷载承载特性．试验结果表明：大直径灌注桩承载力由桩侧阻力与桩端阻力共同承担，但表现出很强的摩擦桩特征，这与桩长过长、桩底岩层较软以及成桩方法有关；在竖向荷载作用下，桩侧阻力由上至下逐步发挥，并逐步达到相应的极限状态；单桩水平最大位移可以取10mm。水平承载力可取900kN．建议采用位移控制设计此类桩基．

Loading Test on the Bearing Capacity of Large-Diameter Filling-Piles

Taking large-diameter filling piles as an example, the vertical and horizontal loading tests of five piles （Ф 1 500 mm） were carded out. The results were arrived at the pile＇s load-settlement curves, the axial forces of different pile＇s section, the lateral load-time-lateral displacement curve, the lateral load-displacement gradient curve, the critical beating capacity and the lateral modulus of subgrade reaction. The load transfers mechanism and loading bearing behavior of the pile were discussed. The test results show the pile mainly behaves as friction piles and the vertical bearing capacity is mainly supplied by side friction resistance and it is perhaps related to the long pile length, the small strength of pile bottom＇s rock and the construction method of pile. The pile＇s maximum horizontal displacement is 10 mm and the horizontal bearing capacity is 900 kN. The pile design should adopt the displacement control method.