Large-scale Direct Shear Test on Interface Characteristics Between Geocell and Desert Sand
Several large-scale direct shear tests were carried out to characterize the reinforcement-soil interface between geocell and desert sand,including direct shear tests on geocell-reinforced desert sand interface with different geocell positions,different shear rates,and different temperatures.The result indicates that under the normal stress of 50,100,150 kPa,taking the upper interface or lower interface of geocell-reinforced layer as the shear surface,the shear stress-shear displacement curves of reinforcement-soil interface under the influence of different shear rates(0.5,1.0,2.0 mm/min)and various temperatures(30,15,0,―15℃)are all characterized by strain softening.Pure desert sand is not sensitive to the variation of shear rate.The shear rate rises from 0.5 mm/min to 3 mm/min when the desert sand shear strength is flat.In contrast,the interface of geocell-reinforced desert sand is sensitive to the variation of shear rate,and the interface shear strength decreases with the increase of shear rate.At the lower shear rate of 0.5 mm/min,the contribution to shear strength from apparent cohesion provided by the geocell is greater.The peak shear stress of geocell-reinforced desert sand does not change much at 30℃ and 15℃.The difference is that the shear strength at 30℃ decreases more quickly to the stationary stage after the peak value.As the temperature decreases,the geocell-soil composite exhibits greater stiffness,and the peak interfacial shear stress increases and moves forward.The increase of geocell stiffness makes the geocell wall less susceptible to tensile deformation,resulting in the weakening of hoop action,and the enhancement of horizontal friction action.It comprehensively shows that the apparent cohesion of reinforced soil shear surface decreases,while the internal friction angle increases.
road engineeringinterface characteristicslarge-scale direct shear testgeocellshear ratetemperature
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