大承载力端承摩擦桩承载性状试验研究

Study on the bearing behavior of friction bearing piles with large bearing capacity

以银川某超高层项目为背景,采用现场静载荷试验方法,探究端承摩擦桩在高应力作用下承载性状,结果表明:桩长45 m、直径1 m的大承载力端承摩擦桩在该地区极限承载力可达30000 kN.应力分级加载下侧阻沿桩身长度发挥曲线近似呈抛物线状;侧阻最佳发挥范围约为桩身2/3段;单桩侧阻的发挥程度与土层性质相关,该地区土层摩阻力较规范建议值提高1.81~2.39倍.大承载力端承摩擦桩承载机制为侧阻初期承担全部上部荷载,随着应力增大,端阻逐渐发挥,而侧阻发挥至到极限值后,由端阻承担上部剩余荷载直至极限,即端阻与侧阻共同承担上部荷载,达到极限承载力时侧阻作用占比74%,端阻作用占比26%.上述结论为日后该地区工程建设乃至大承载力端承摩擦桩桩基研究提供参考与帮助.

Based on a super high-rise project in Yinchuan,the static load test method was used to investigate the bearing behavior of the end-bearing friction pile under high stress.Results show that the bearing capacity of the large bearing capacity end bearing friction pile with a length of 45m and a diameter of 1m is in the region.The force can reach 30,000 kN.Under the stress grading loading,the side resistance along the length of the pile body is approximately parabolic;the best range of side resistance is about 2/3 of the pile body;and the degree of lateral resistance of the single pile is related to the nature of the soil layer.The resistance is 1.81 to 2.39 times higher than the recommended value.The bearing capacity of the bearing pile with large bearing capacity is assumed to bear all the upper load at the initial stage of the side resistance.As the stress increases,the end resistance gradually take place,and after the side resistance reaches the limit value,the upper residual load is taken up to the limit by the end resistance,ie the end resistance and the side resistance may share the upper load.When the ultimate bearing capacity is reached,the side resistance accounts for 74%,and the end resistance accounts for 26%.The above conclusions provide reference and help both for the future research of the project construction and even for the research on the large bearing capacity end bearing friction pile foundation.