Babak Azari is a member of Centre for Built Infrastructure Research since March 2010. He has developed a software program to calculate settlement and pore water pressure of ground improved sites applying preloading assisted vertical drains. He Conducted an array of laboratory tests (Rowe cell and consolidometer tests) to verify developed model with in-house test results. The large scale Rowe Cell test was one of the first tests carried out in this field which was considering soil disturbance caused by the installation of vertical drains. Furthermore, he simulated Ska-Edeby and Vasby test fills projects to verify the developed program and also to perform parametric study on soil shear strength and permeability reduction caused by installation of vertical drains on the long term behaviour of soft soils. Babak chaired CBIR weekly meetings in the school of Civil and Environmental Engineering (UTS) in 2010.
Achieved the “UTS 2014 HDR Publication Award” granted to researchers who publish papers in high quality journals
Successfully developed a program capable of simulating ground improved sites to calculate settlement and pore water pressure in soil considering the combined effects of soil creep, disturbed property zone (shear strength and permeability reduction) surrounding the vertical drains and nonlinear permeability variations during the consolidation process
Designed and modified the available Consolidometers in the soil lab, eliminating the need to outsource
Azari, B, Fatahi, B & Khabbaz, H 2016, 'Assessment of the Elastic-Viscoplastic Behavior of Soft Soils Improved with Vertical Drains Capturing Reduced Shear Strength of a Disturbed Zone', International Journal of Geomechanics, vol. 16, no. 1, pp. B4014001-B4014001.View/Download from: UTS OPUS or Publisher's site
Soil disturbance induced by the installation of vertical drains reduces the horizontal soil permeability and shear strength in the disturbed zone. Thus, the soil disturbance contributes to the reduced overconsolidation ratio (OCR) of the soil in the vicinity of drains, influencing soil deformation. Although a significant amount of research has been conducted on the effect of permeability variations in the smear zone, the influence of the reduced shear strength in the smear zone on the ground behavior has not been investigated. In this study, a numerical solution adopting an elastic-viscoplastic model with nonlinear creep function in combination with the consolidation equations has been developed. Moreover, the effects of shear strength variation in the disturbed zone on the time-dependent behavior of soft soil deposits improved with vertical drains and preloading have been studied. The applied elastic-viscoplastic model is based on the framework of the modified Cam-clay model, capturing soil creep during excess pore-water pressure dissipation. Furthermore, nonlinear variations of the creep coefficient with stress and time as well as the permeability variations during the consolidation process are considered. The predicted results have been compared with available field measurements. According to the results, the OCR profile of the disturbed zone influences the viscoplastic strain rate, the creep strain limit, and consequently the soil deformation.
Azari, B 2014, 'Elastic Visco-Plastic Behaviour of Soft Soils Improved with Preloading and Vertical Drains', GeoHubei 2014, GeoHubei 2014, ASCE, China, Hubei, pp. 17-24.
Azari, B, Fatahi, B, Khabbaz, H & Vincent, P 2014, 'Elastic Visco-Plastic Behaviour of Soft Soils Improved with Preloading and Vertical Drains', Pavement Performance Monitoring, Modeling, and Management (GSP 254):GeoHubei 2014, Sustainable Civil Infrastructures: Innovative Technologies and Materials: GeoHubei, ASCE, China, pp. 17-24.View/Download from: UTS OPUS or Publisher's site
In this study, a numerical solution adopting an elastic visco-plastic model with nonlinear creep function incorporated in the consolidation equations has been developed to investigate the time dependant behaviour of soft soil deposits improved with vertical drains and preloading. The employed elastic visco-plastic model is based on the framework of the modified Cam-Clay model capturing soil creep during excess pore water pressure dissipation. Besides, nonlinear variations of creep strain rate with stress and time and permeability variations during the consolidation process are considered. The developed numerical model is validated against Ska-Edeby test fill with the available long-term settlement and excess pore water pressure monitoring results for the soft clay deposit improved with vertical drains assisted preloading. Practicing engineers can adopt the developed code and guidelines to predict the long term performance of embankments on soft soil improved using preloading.
Azari, B, Fatahi, B & Khabbaz, H 2013, 'Long-term Viscoplastic Behaviour of Embankments Built on Improved Soft Soil Using Vertical Drains', GEOCONGRESS 2013, Geo congress of the Geo-Institute of ASCE, American Society of Civil Engineers, San Diego, California, pp. 2124-2132.View/Download from: UTS OPUS or Publisher's site
In this paper, a nonlinear elastic visco-plastic model is incorporated in the general consolidation equation to investigate the time dependent performance of embankments constructed over deep soft soil deposits stabilised with prefabricated vertical drains (PVDs) and preloading. To model vertical and radial consolidation processes, a finite difference formulation is implemented for fully coupled axisymmetric consolidation. The developed numerical model is validated against VÃ¤sby test fill with the available long-term settlement monitoring results for the soft clay deposit improved with PVDs assisted preloading. Practicing engineers can adopt the developed code and guidelines to predict the long term performance of embankments on soft soil consolidated using preloading.
Azari, B, Fatahi, B & Khabbaz, H 2011, 'Application of Creep Ratio Concept for Estimating Post-Constriction Settlement of Deep Soft Clay Deposits', ICAGE 2011 - Proceedings of the International Conference on Advances in Geotechnical Engineering, International Conference on Advances in Geotechnical Engineering, Curtin University, Perth, Australia, pp. 127-133.View/Download from: UTS OPUS
Two main different approaches have been previously proposed to predict time dependent behaviour of soft soils. (I) end of primary consolidation is unique although creep starts simultaneously with primary consolidation (Hypothesis A); (II) As creep and primary consolidation commence at the same time and creep is a time dependant phenomenon, then end of primary consolidation cannot be unique (Hypothesis B). In Hypothesis A, soil settlement is divided into two parts: primary consolidation and secondary compression which follows by primary consolidation. In Hypothesis B, soil settlement is estimated based on elasto-viscoplastic constitutive model simulating soil creep and consolidation settlement simultaneously. In this study, details of first approach based on creep ratio ( ) concept is discussed with a worked example to be used by practicing geotechnical engineers.
Hemmati, S, Azari, B & Gatmiri, B 2008, 'Numerical modelling of the soil surface moisture changes due to soil-atmosphere interaction', UNSATURATED SOILS: ADVANCES IN GEO-ENGINEERING, 1st European Conference on Unsaturated Soils, CRC PRESS-TAYLOR & FRANCIS GROUP, Durham, ENGLAND, pp. 791-796.View/Download from: Publisher's site