Small strain stiffness and stiffness degradation curve of Bangkok Clays

The small strain stiffness and the stiffness degradation curve of soils are required in advanced numerical analyses of geotechnical engineering problems. The shear modulus at small strain (G_max) and the reference shear strain parameter (γ_0.7) are, for instance, two of the input parameters in a finite element analysis with the hardening soil model with small strain stiffness. The stiffness and strength parameters for the hardening soil model of soft and stiff Bangkok Clays has recently been published (Surarak et al., 2012). This paper is a continuation on the previous study on the stiffness of Bangkok Clay, and focuses on the small strain characteristics. The data are from the Bangkok MRT Blue line project as well as comprehensive studies at Chulalongkorn University and the Asian Institute of Technology. Based on these laboratory and field testing data, the parameters G_max and γ_0.7 can be determined using well-known empirical correlations and the concept of threshold shear strain. Finally, a comparison between the measured data and predictions is made.     

Reliability analysis of unsaturated soil slope stability under infiltration considering hydraulic and shear strength parameters

Bulletin of Engineering Geology and the Environment - In general, soil properties, including shear strength and hydraulic parameters, are characterised as a spatial variability. This paper aims to...     

Swell-shrink behaviour of cement with fly ash-stabilised lakebed sediment

Bulletin of Engineering Geology and the Environment - Dredged river or lake sediments are ideal for repurposing in engineering applications. Unfortunately, the low strength of these materials makes...     

Finite element analysis of a deep excavation: A case study from the Bangkok MRT

The Bangkok metropolitan area, located on a thick river soft clay deposit, has recently started a construction project on a mass rapid transit underground railway (MRT). This paper presents a finite element study on the Bangkok MRT underground construction project. The excavation of Sukhumvit Station was selected as the case study for the FEM numerical modelling in this paper. The numerical study focuses on the initial input on the ground conditions and the constitutive soil models. The geotechnical parameters were selected based on the soil investigation reports carried out for the purpose of the construction. The parameters selected for the constitutive models used in the FEM analysis were calibrated against the laboratory testing results. Finally, all the FEM simulations were compared with the data from field investigations.     

Model for Shear Response of Asphaltic Concrete at Different Shear Rates and Temperatures

This paper presents a model for shear response of asphaltic concrete, taking into account of strain-rate and temperature effects. The model employs rate-dependent hyperplasticity theory, which is based on a thermomechanical framework. A principle of the theory is that the entire constitutive behavior can be defined by two scalar potentials: an energy potential and a flow potential. The viscous behavior of the model corresponds to the results of rate process theory and defines the strain-rate and time dependent behavior. The initial modulus and shear strength are each assumed to be exponential functions of the inverse of temperature. The model is verified and calibrated against the unconfined compression test data for asphaltic concrete at different strain rates and temperatures. A viscoelastic damage model is also addressed to make a comparison with the model developed here. Comparison between the test data, the predictions of the new model, and the predictions of the viscoelastic damage model are discussed.