Prediction Of Pullout Resistance Of Compacted Grouted Soil Nail Based On Cone Penetration Test

The new compaction grouted soil nail is a slope reinforcement structure with better pullout resistance than traditional grouting soil nails through structural optimization.As an economical and fast in-situ testing technique in engineering,cone penetration test is often directly applied to predict the bearing capacity of pile foundations.Considering the similarities between the bearing characteristics of pile foundation and the pull-out characteristics of compaction grouted soil nails,this paper proposed a method based on CPT to predict the pullout resistance of compaction grouted soil nails.Firstly,the pullout model test and cone penetration model test system of compaction grouted soil nail have been developed.Through the model test,the relationship between bulb pressure/tip resistance and the displacement during the pullouting/penetration process under different over pressure was obtained.The results show that the ultimate pullout resistance/tip resistance increases with the increase of the over pressure,and the growth trend is greatest in the early stage of the pullout process.The trend decreases with the increase of displacement until the pullot resistance tends to be stable.There is a significant linear relationship between the bulb pressure and the tip resistance.Then,a new method is proposed: using the cone penetration test method to predict the pull out resistance of the compaction grouted soil nail,and according to the test results,a new prediction formula for the pulling force of the soil nail based on the cone tip resistance is established,which provides a reference for quickly placing soil nails on a slope.Finally,the model test was further analyzed by numerical simulation software ABAQUS,the dry density of soil was changed,and the results of cone penetration test and soil nail pull out resistance under the corresponding boundary conditions were obtained.The verification is carried out and the influence of the grouting bulb radius on the formula is discussed.This thesis includes 48 figures,10 tables and 89 references.