自钻式锚杆连接套与中空锚杆体连接失效分析

Splicing failure analysis of coupler and hollow bar of self-drilling anchor

基于材料塑性双线性随动硬化模型,在有限元软件ANSYS中建立自钻式锚杆中空锚杆体与连接套螺纹连接数值模型。研究了自钻式锚杆在承受轴向拉伸时,中空锚杆体与连接套的应力分布及变化规律以及二者的变形情况。进一步分析了导致连接套与中空锚杆体螺纹连接失效的原因。最后采取试验的对数值计算结果进行对比。结果显示,连接套与中空锚杆体螺纹连接失效的表现形式主要为螺纹拉脱,主要原因在于在自钻式锚杆在承受轴向载荷时,连接套与中空锚杆体径向会产生变形,连接套会发生膨胀,而中空锚杆体会发生"颈缩"现象;另外,在承受较大载荷时,中空锚杆体与连接套螺纹旋合段螺纹牙会发生塑性变形,螺纹牙会发生挤压变平。

Based on the material plastic bilinear follower hardening model,a numerical model of the threaded connection between the self-drilling anchor hollow anchor body and the connecting sleeve was established in the finite element software ANSYS.The stress distribution and variation of the hollow anchor body and the connecting sleeve and the deformation of the two are studied when the self-drilling anchor is subjected to axial stretching.The reason for the failure of the threaded connection between the connecting sleeve and the hollow anchor body was further analyzed.Finally,the results of the experimental numerical calculations were compared.The results showed that the failure of the threaded connection between the connecting sleeve and the hollow anchor body was mainly the thread pull-off.The main reason was that the radial deformation of the connecting sleeve and the hollow anchor body occurs when the self-drilling anchor was subjected to the axial load.The connecting sleeve would expand,and the hollow anchor body would had a "necking" phenomenon;in addition,when subjected to a large load,the hollow anchor body and the threaded portion of the connecting sleeve would be plastically deformed,and the thread would occur.The thread would be squeezed and flattened.