螺旋土钉钻进成孔扭矩分析

Analysis of torque on helical soil nail drilling into strata

为研究木塑复合材料螺旋土钉钻进成孔过程中受力的特点,对螺旋土钉进行现场螺旋钻入试验,分析试验现象并推导成孔扭矩的理论计算公式.综合运用试验和解析方法,分析土钉有效入土长度、螺纹宽度、土钉直径、螺距和土质在同等条件下分别对螺旋土钉钻进成孔过程的影响.结果表明:有效入土长度和螺纹宽度越小则扭矩越小;杆体直径越小,螺纹直径越大,螺旋土钉钻入扭矩越小;螺距略大于螺纹直径时所需成孔扭矩最小;土质越硬,螺旋土钉钻入扭矩越大,成孔越困难,因此木塑复合材料螺旋土钉适用于软土.

The field experiments were done to study the forces on wood-plastic-composites(WPC)helical soil nail drilling into soil strata.A formula of the drilling torque was derived according to the experimental data.The experimental and analytical results showed that the drilling process of helical soil nail was affected by many factors,such as effective length of soil nail in the strata,width of screw thread,diameter of soil nail,pitch of screw thread and soil properties.Results show that the shorter the effective length of soil nail in the strata and the smaller the width of screw thread,the lower the needed torque.The smaller the rod body diameter and the bigger the screw thread diameter,the lower the needed torque.The minimum torque occurs when pitch of screw thread is slightly larger than the diameter of screw thread.It is difficult for WPC helical soil nail to drill in hard soil so that it is suitable for soft soil.