Study On The Shear Performance Of The Interface Between The New Drainage Geogrid And Cohesive Soil

The interface properties of reinforced materials and fillers directly affect the safety of reinforced earth engineering,and the interface properties of reinforced soils are closely related to the properties of fillers and reinforced materials.The specification requires the use of coarse-grained soils such as gravel soil and sand soil with better gradation as fillers,while cohesive fillers are generally considered as non-ideal fillers,which greatly limits the scope of application of reinforced soil technology.The water discharged during the consolidation process of the viscous filler will reduce the interface characteristics of the reinforced material and the filler,resulting in a reduction in the restriction of the reinforcing material on the viscous filler and the effect of the reinforced material.In order to improve the role of reinforced materials in viscous fillers,a new type of drainage geogrid was designed and fabricated in this paper,and the geogrid is composed of two-way fiberglass geogrid and drainage materials.A large-scale direct shear test was used to study the influence of the research factors such as the type,quantity,layout of the drainage materials and consolidation pressure on the shear properties of the interface between the new drainage geogrid and cohesive soil.The following results have been achieved:(1)After 6 hours of consolidation at the same consolidation pressure,compared with the drainage geogrid using non-woven geotextile,the moisture content of the soil samples near the drainage geogrid with 4DG-wicking fiber and Coolplus fiber was respectively reduced by2～11.6% and 1～5.5%;the moisture content of the soil sample near the reinforced soil interface decreases with the increase in the number of 4DG-wicking fibers and the number of drainage belts in the geogrid.(2)For three drainage geogrids made of three drainage materials,a large direct shear test was used to study the shear strength of the interface between them and the clay.Before the test,the reinforced soil samples were consolidated at the same pressure for 6 hours.Compared with the drainage geogrid using non-woven geotextile,the interface shear strength of the drainage geogrid using 4DG-wicking fiber is increased by 13.5～35.3%,and the interface shear strength of the drainage geogrid using Coolplus fiber is increased 6.5～15%,and their growth rate increases with the increase of consolidation pressure.(3)Compared with the new drainage geogrid using non-woven geotextile,the interface friction angle between the new drainage geogrid using 4DG-wicking fiber and cohesive soil is increased by 45.4%,and the interface friction angle between the new drainage geogrid using Coolplus fiber and cohesive soil is increased by 21.9%.(4)After 6 hours of consolidation at the same consolidation pressure,the shear strength of the reinforced-soil interface increases with the increase in the number of 4DG-wicking fibers in the geogrid.Compared with the ordinary geogrid,the interface shear strength of the drainage geogrid using 300 4DG-wicking fibers is increased by 38.1～60%,and the interface shear strength of the drainage geogrid using 600 4DG-wicking fibers is increased by 40～88%,and their growth rate increases with the increase of consolidation pressure;in addition,with the increase in the number of 4DG-wicking fibers in the geogrid,the friction angle at the interface between the reinforcement and soil will also increase;when the number of4DG-wicking fibers in the geogrid is 150,the shear strength and friction angle of the reinforced soil interface increase with the number of drainage belts arranged in the geogrid.