砂土中钢管螺旋桩安装扭矩的研究

Research on the installation torque of steel screw piles in sand

为了能够准确预测钢管螺旋桩的承载能力,以满足工程机械高效施工作业的需求,对钢管螺旋桩的安装扭矩进行了研究.给出了砂土中钢管螺旋桩安装扭矩的理论计算模型,考虑到安装过程中土体扰动,引入螺旋进给率这一衡量土体扰动的指标,同时进行现场实验以验证模型可靠性.研究发现:叶片螺距与直径的比值p/D对安装扭矩有重要影响,为了让叶片运动轨迹一致,叶片间距S取螺距p的整数倍,结果表明p/D在0.2~0.3之间较为合理.此外,安装扭矩与抗拔承载力存在一定的关联,可对钢管螺旋桩进行抗拔承载力预测.

In order to predict the bearing capacity of screw piles accurately and satisfy the needs of the efficient construction work,the installation torque of steel screw pile is studied.The theoretical model for estimating the installation torque of steel screw piles in sand is first proposed in this paper.Considering the soil disturbance in the installation process,the screw feed rate as a measure of disturbance is also introduced.The field test is used to verify the reliability of the model.Researches show that the ratio of the pitch of the blade to the diameter p/D has a significant influence on the installation torque.In order to ensure the consistent of the blade trajectory,the blade spacing S is the integral multiple of the standard pitch p .It is found that p/D is reasonable between 0.2~0.3.Moreover,there is a certain relationship between the installation torque and the uplift bearing capacity,which can be used to predict the uplift bearing capacity of the steel screw piles.