Field tests on pull-out force of a new soil nail with multiple bulbs under cyclic pull-out loading
Compared with the traditional soil nails,the new soil nails with multiple bulbs have the characteristics of pulling-out hardening,and its pull-out behaviors in soil slope performance better.In order to explore the slope reinforcement effect of the soil nail with multiple bulbs under actual work conditions and compare it with that of traditional soil nail,seven groups of new and traditional soil nails field cycle tension tests were carried out.The effects of grouting technique,bulb spacing and buried depth on the pull-out force and its effective rate of soil nails were studied.Furthermore,the proportion of elastic and plastic pull-out displacement of soil nails under each cycle was investigated,and its internal mechanism was analyzed.The test results show that the grouting technique has a significant effect on the pull-out force of soil nails under cyclic tension.The pull-out force of soil nails with improved compaction grouting technique and direct compaction grouting technique is far beyond the traditional one,and the hardening phenomenon at the initial stage of pulling-out is more obvious.The soil nails with improved compaction grouting technique have the largest effective rate of pull-out force,followed by the direct compaction grouting technique,and the traditional one is the smallest.From the overall trend,the effective rate of pull-out force of new soil nails is decreasing,and the traditional one is increasing.Although the improved compaction grouting technique cannot increase the proportion of elastic pull-out displacement of soil nails,it can significantly improve the ultimate pull-out force.The bulb space distance has little effect on the pull-out force and the effective rate of pull-out force of the soil nail with multiple bulbs,which is mainly affected by the strength of surrounding soils.The buried depth affects the ultimate pull-out force of the soil nail with multiple bulbs,and a larger of the buried depth leads to the greater of the ultimate pull-out force and the faster rate of the initial pull-out force.And the trend of the effective rate of pull-out force decreasing with the pull-out displacement is more obvious.The results can provide guidance for improving the reinforcement performance of the soil nail with multiple bulbs and optimizing the engineering application.
soil nailpull-out hardeningcyclic pull-outmultiple bulbsfield test
万方数据
维普
