A Visco-hypoplastic Constitutive Model for Rolled Asphalt

Experience has shown that the durability of “high-modulus” asphalts made with modified bitumen is unsatisfactory. The misdirected “development” forced in recent decades necessitates a more accurate understanding of the mechanical behavior of rolled asphalts, i.e., constitutive formulation of a numerical asphalt model. The authors elaborate a numerical procedure to model the visco-hypoplastic constitutive behavior of the rolled asphalts by the appropriate composition of the hypoplastic theory of soil mechanics and, taking into account the existing asphalt models. This proposal is justified because rolled asphalt is nothing more than an aggregate skeleton of mineral origin, the voids of which are filled with high-viscosity bitumen. The model allows to quantify the interaction of the two components, such as the formation of ruts due to pressure on the bitumen, the formation of cracks due to cooling-induced tensile stresses, and the viscous behavior of asphalt. Validity of this complex numerical model can already be considered proven theoretically, but it still needs to be experimentally verified for the viscous behavior. This new constitutive model has important theoretical and practical consequences such as a new visco-hypoplastic model of rolled asphalt as partially saturated granular material with cooling-induced isotropic residual stresses.

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A simple hypoplastic model for overconsolidated clays

10.31224/osf.io/kxsnv ◽

2021 ◽

Author(s):

shun wang ◽

Wei Wu

Keyword(s):

Constitutive Model ◽

Structure Tensor ◽

History Dependence ◽

Hypoplastic Model ◽

Clay Model ◽

Modified Cam Clay ◽

Overconsolidated Clays ◽

Independent Parameters ◽

Hypoplastic Constitutive Model ◽

Cam Clay

This paper presents a simple hypoplastic constitutive model for overconsolidated clays. The model needs five independent parameters and is as simple as the modified Cam Clay model but with better performance. A structure tensor is introduced to account for the history dependence. Simulations of various elementary tests show that the model is capable of capturing the salient behavior of overconsolidated clays.

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Influence of High Viscosity Petroleum Resin (HV-PR) on the Intermediate and High Temperature Performances of Styrene–Butadiene–Styrene Block Copolymer (SBS) Modified Bitumen

Arabian Journal for Science and Engineering ◽

10.1007/s13369-021-06550-2 ◽

2022 ◽

Author(s):

Wengang Zhang ◽

Ling Zou ◽

Yan Wang ◽

Jianping Liu ◽

Chengxu Yang ◽

...

Keyword(s):

High Temperature ◽

Block Copolymer ◽

High Viscosity ◽

Modified Bitumen ◽

Petroleum Resin ◽

Styrene Butadiene Styrene ◽

Styrene Butadiene ◽

Butadiene Styrene

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Hypoplastic constitutive model in SPH

Computer Methods and Recent Advances in Geomechanics ◽

10.1201/b17435-330 ◽

2014 ◽

pp. 1863-1867

Author(s):

C Peng ◽

W Wu ◽

H Yu

Keyword(s):

Constitutive Model ◽

Hypoplastic Constitutive Model

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Validation of a simple hypoplastic constitutive model for overconsolidated clays

Acta Geotechnica ◽

10.1007/s11440-020-01105-5 ◽

2020 ◽

Author(s):

Shun Wang ◽

Wei Wu

Keyword(s):

Laboratory Tests ◽

Constitutive Models ◽

Standard Laboratory ◽

Hypoplastic Model ◽

Proposed Model ◽

Modified Cam Clay ◽

Overconsolidated Clays ◽

Hypoplastic Constitutive Model ◽

Comparison With Experiments ◽

Cam Clay

AbstractHypoplastic constitutive models are able to describe history dependence using a single nonlinear tensorial function with a set of parameters. A hypoplastic model including a structure tensor for consolidation history was introduced in our previous paper (Wang and Wu in Acta Geotechnica, 2020, 10.1007/s11440-020-01000-z). The present paper focuses mainly on the model validation with experiments. This model is as simple as the modified Cam Clay model but with better performance. The model requires five parameters, which are easy to calibrate from standard laboratory tests. In particular, the model is capable of capturing the unloading behavior without introducing loading criteria. Numerical simulations of element tests and comparison with experiments show that the proposed model is able to reproduce the salient features of normally consolidated and overconsolidated clays.

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Measurement and Calibration of the Parameters of Hypoplasticity Model for an Iraqi Soil

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.857.243 ◽

2020 ◽

Vol 857 ◽

pp. 243-252

Author(s):

Aysar Hassan Subair ◽

Ala Nasir Aljorany

Keyword(s):

Constitutive Model ◽

Void Ratio ◽

Initial Stresses ◽

Model Parameters ◽

State Variables ◽

Soil Behavior ◽

Dense Sand ◽

Hypoplastic Model ◽

Material Parameters ◽

Wide Range

There are many constitutive models that have been used to model the mechanical behavior of soils. Some of these models are either unable to represent important features such as the strain softening of dense sand or required many parameters that can be hard to obtain by standard laboratory tests. Because of that, a more reliable constitutive model, which is capable to capture the main features of the soil behavior with easily obtained parameters, is required. The Hypoplasticity model is considered as a promising constitutive model in this respect. It is considered as a particular class of rate non-linear constitutive model at which the stress increment is expressed in a tensorial equation as a function of strain increment, actual stress, and void ratio. The hypoplastic model required only eight material parameters (critical friction angle critical, maximum and minimum void ratio respectively), granular stiffness hs and the model constants n, α, β). The appealing feature of the hypoplastic model is that the material parameters are separated from the state variables (void ratio and the initial stresses). This feature enables the model to simulate the soil behavior under a wide range of stresses and densities with the same set of material parameters. In this research, a brief description of the Hypoplasticity model is presented. Detailed discussions regarding the measurement and calibration of the model parameters of an Iraqi soil are then exposed. It is concluded that only Consolidated Drained (CD) triaxial test, oedometer test, and the well-known limit density tests are needed to get all the parameters of the hypoplasticity model.

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