An EVP Double-Yield Nonstationary Flow Surface Model for Soft Clay

Figure 14

The schematic diagram of both nonstationary compression and shear surfaces. For a given viscoplastic strain, the stress point which lies in a flow surface will be reached at different points B1, B2, or B3 over time (t). When soil is seen as an elastoplastic material and viscoplastic strains remain constant, the stress point will be reached at the same point (such as B1) along a given load path, which is independent of time.