在管道接头外表面焊缝中心处的轴向残余应力为压应力，而环向残余应力为拉应力。

On the outer surface of the pipe, the axial residual stresses of the weld and in its vicinity are compressive while the hoop stresses keep tensile.

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由于套筒材料相对为软性，套筒材料被压入攻丝工件的粗糙表面。

Thanks to the soft sleeve material, anchorage is achieved by the flow of sleeve material into the surface roughness of the drilled hole.

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每层的松铺厚度以30 cm为宜，摊铺阼度应均匀，压实后的表面应平整。

Each layer of loose paving thickness should be 30cm, paving the last degree should be uniform, the surface should be smooth after compaction.

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