Experimental Evaluation Of The Performance Of A Geotextile For A Compaction-grouted Soil Nail

A new idea that adopts a geotextile instead of a latex membrane to improve the performance of a compaction-grouted soil nail,was proposed.Based on the self-developed test device,a series of laboratory tests were carried out,and the advantages of geotextile for improving the compaction-grouted soil nail were comprehensively discussed and evaluated,which laid a good foundation for promoting the soil nail from theoretical research to practical application.The main research contents of this thesis are as follows:(1)Based on current research,this thesis summarized and analyzed the problems existing in the use of latex membrane as the grout bulb inclusion in compaction-grouted soil nail,and put forward a new idea of using geotextile instead of latex membrane to improve the performance of a compaction-grouted soil nail.A test device for testing geotextile’s filtration performance,a small-scale penetration test device based on CPT,and a pull-out model test device of soil nail were developed.The performance test of the device was carried out and debugged.(2)Based on the self-developed device for testing geotextile’s filtration performance,and considering the key factors of the compactiongrouted soil nail,a series of cement slurry filtration tests were carried out to study the influence of water-cement ratio,slurry volume,and grouting pressure on the geotextile’s filtration performance.The variations in watercement ratio and filtration time,derived from the changes in the aforementioned influencing factors,during pressure grouting were obtained.It is preliminarily proved that the use of geotextile can not only avoid cavities in grout bulbs,but also significantly reduce the watercement ratio in the grout bulbs(increase the strength).(3)Based on the self-developed CPT small-scale penetration test device,a series of penetration tests were carried out on the sand samples before and after the slurry was filtered into the soil through the geotextile.The influence of the infiltration of the cohesive substances of the cement slurry on the strength of the soil was evaluated,and the influence mechanism of the filtration effect of the geotextile on the strength of the soil around the grout bulb and the pull-out force of the soil nail was explored.(4)The material composition and pore characteristics of cement slurry,geotextile,and sand samples before and after filtration were analyzed by a combination of microscopic and macroscopic methods.The mechanism of strengthening grout bulb and increasing pull-out force of the soil nail after using geotextile was revealed.Finally,based on the self-developed soil nail pull-out model test device,two groups of comparative pull-out tests of compaction-grouted soil nail with a geotextile and a latex membrane were carried out,which directly verified the superiority of improving the compaction-grouted soil nail by a geotextile.