1 School of Highway, Chang’an University, Xi’an 710064, China 2 Beijing Institute of Space Launch Technology, Beijing 100076, China 3 Key Laboratory of Infrastructure Durability and Operation Safety in Airfield of CAAC, Tongji University, Shanghai 201804, China 4 Ankang Transportation Construction Investment Group Corporation, Ankang 725099, Shaanxi, China
Abstract: In order to investigate the shear characteristics of loess, the Mohr-Coulomb (M-C) model parameters of internal friction angle φ and cohesion c, and the Ducker-Prager (D-P) model parameters of β and d were obtained, and the water content ω was controlled to be 9.5%, 11.5%, 13.5%, 15.5%, and 19.5%, and the static triaxial instrument of GDS(Geotechnical digital systems, GDS) was used to conduct unconsolidated and undrained triaxial shear tests under 100, 200, and 300 kPa pressures, finite element simulations were performed to analyze the error of the model in characterizing the shear properties of loess. The results showed that when ω was 9.5%, the stress-strain curves of soil samples under the 100 kPa and 200 kPa pressures showed "softening" phenomenon, and when ω was in the range of 11.5%—19.5%, the stress-strain curves of soil samples under all pressures showed "hardening" phenomenon. The internal friction angle φ and the cohesion c, β and d of the soil decreased with the increase of water content and increased with the increase of the perimeter pressure; when the water content was greater than the optimum water content, the cohesion c and d would decrease rapidly. Finite element simulation compared the M-C and D-P models and found that the M-C model could better reflect the loess shear characteristics. The mechanical parameters of the M-C and D-P models were finally obtained, and the fitting equations were given to predict the model parameters of soil samples with a compaction degree of 94% and water content in the range of 9.5%—19.5%, which could provide reference for engineering construction.
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