Dr Chao Yang
School of Engineering
- Phone:(02) 4985 4996
Chao Yang completed his Ph.D study in Geotechnical Engineering from Tongji University, China and École nationale des ponts et chaussées (ENPC), France, in July 2008. His research focused on the mechanical behaviour of unsaturated cemented soils (French loess) subjected to cyclic transportation loading (i.e., high speed railway, road). He has a BEng in Construction Engineering and a MEng in Engineering Mechanics in Henan Polytechnic University, China. Before he came to the University of Newcastle, he worked as an engineer in Shanghai Tunnel Engineering Co., Ltd., mainly responsible for studying and implementing critical construction techniques in shield tunneling beneath both operating and under-construction runways. In the spring of 2009, he worked in ENPC for three months and developed a piece of engineering software aiming to evaluate the TGV (French high speed railway) foundation stability using field penetration tests.
(1) Constitutive modelling of unsaturated soils (2) Seepage analysis in engineered soil covers (3) Foundation stability analysis using shear-wave velocity method (4) Shield tunnel construction in soft clays (5) Soil nailing technique (6) Numerical simulation and Software development.
- Doctor of Engineering, Tongji University - China
- Master of Engineering, Henan Polytechnic University - China
- Geotechnical Engineering
- Shield Tunnel Construction
- Unsaturated Soil Mechanics
- French (Fluent)
Fields of Research
|090501||Civil Geotechnical Engineering||35|
|090699||Electrical and Electronic Engineering not elsewhere classified||20|
|091399||Mechanical Engineering not elsewhere classified||45|
|Title||Organisation / Department|
|Reseach Academic||University of Newcastle
School of Engineering
|Dates||Title||Organisation / Department|
|1/02/2009 - 1/04/2009||Postdoctoral Researcher||Ãcole nationale des ponts et chausses, France
|Dates||Title||Organisation / Department|
|1/09/2008 - 1/09/2009||Civil Engineer||Shanghai Tunnel Engineering Co Ltd, China
TBM Branch Company
For publications that are currently unpublished or in-press, details are shown in italics.
Journal article (20 outputs)
Yang C, Carter JP, 'Isotach Elastoplasticity: A Case Study on Osaka Bay Clay', Indian Geotechnical Journal, 47 161-172 (2017)
Â© 2016, Indian Geotechnical Society. The theory of isotach elastoplasticity (IEP) is applied to investigate the strain rate and time effects in Osaka Bay clay from Japan. The IEP... [more]
Â© 2016, Indian Geotechnical Society. The theory of isotach elastoplasticity (IEP) is applied to investigate the strain rate and time effects in Osaka Bay clay from Japan. The IEP theory considers geomaterials like clays as an overdamped oscillatory physical system, for which the strain rate (analogous to the vibration frequency) decays in an exponential manner. This feature can be captured by a characteristic strain rate and time relationship. The evolutionary change of strain rate is found to affect the mechanical response of soft clays in an isotach manner. A loadingÂ¿isotach (LI) yield curve is proposed in the stress and strain rate plane. Combination of the characteristic strain rate and time relationship in an isotach manner into the framework of critical state soil mechanics renders an isotach (rate-dependent) elastoplastic (IEP) constitutive model. A total of 9 model parameters is required, and their values can be properly determined via conventional laboratory tests. The validity of the proposed IEP is demonstrated using experimental data for Osaka Bay clay under various stress paths and strain rates, namely, long-term creep, constant rate of strain loading, relaxation, and their combination. Comparison of the model predictions and experimental results demonstrates that the theory of isotach elastoplasticity can be successfully applied to capture the strain rate and time effects on the mechanical behaviour of Osaka Bay clay.
Yang C, Carter JP, Sheng D, Sloan SW, 'An isotach elastoplastic constitutive model for natural soft clays', Computers and Geotechnics, 77 134-155 (2016) [C1]
Â© 2016 Elsevier Ltd. The time and strain rate dependency observed in natural soft clays is formulated within the framework of conventional elastoplasticity. Creep of soft clays i... [more]
Â© 2016 Elsevier Ltd. The time and strain rate dependency observed in natural soft clays is formulated within the framework of conventional elastoplasticity. Creep of soft clays is essentially like the response of an overdamped oscillatory system, i.e., the strain rate decays in an exponential manner. A characteristic strain rate and time relationship is presented based on data from creep tests on a large number of different soft clays. The evolutionary change of strain rate is found to affect the mechanical response of soft clays in an isotach manner. Taking strain rate as another stress-like variable, a loading-isotach (LI) yield curve is proposed, which describes the combined hardening mechanisms of loading and variation of strain rate. Incorporation of this LI yield curve into critical state soil mechanics results in an isotach elastoplastic (IEP) model in triaxial stress-strain-strain rate space, which has been dubbed 'Hunter Clay'. The effects of fabric anisotropy and inter-particle cementation, which are typical features of natural soft clays, are also introduced to produce an advanced hierarchical constitutive model for soft clay. Qualitative predictions are first described and compared with the characteristic behaviour of natural soft clays. Experimental validations using test data for two soft clays are then carried out, and comparisons of the model predictions and experimental data demonstrate the capability of the model in reproducing realistic behaviour of natural soft clays. This work confirms that the complex mechanical behaviour of natural soft clays can be reproduced satisfactorily within the general framework of classical plasticity theory.
Sun B, Zeng S, Guo S, Yang C, 'Variation Characteristics of Stress Wave Speed for Anchorage System Under Instantaneous Excitation', Geotechnical and Geological Engineering, (2015) [C1]
Dynamic nondestructive testing is widely used to evaluate the bolt anchorage quality in an anchorage system. The consolidating wave speed, stress wave speed for anchorage system u... [more]
Dynamic nondestructive testing is widely used to evaluate the bolt anchorage quality in an anchorage system. The consolidating wave speed, stress wave speed for anchorage system under instantaneous excitation, is a required parameter for the evaluation. However, it is very difficult to determine the wave speed since it is affected by many factors. In order to solve the problem, this paper tries to establish the relationships between consolidation wave speed and wave speed in anchorage medium. This paper used dynamic nondestructive testing for measuring consolidation wave speed and wave speed in anchorage medium through experiment. The consolidation wave speed is measured by the grouted bolts in concrete fabricated by casting the bolts within one cubic concrete block with the dimensions of (600 mm Ã 600 mm Ã 2400 mm) around steel bars, and the wave speed in anchorage medium is measured by concrete specimens. The results indicate that the consolidation wave speed ranges from wave speed in concrete to that in free steel bar, the consolidation wave speed and wave speed in concrete vary in exponential law, and that they are mutually symmetric. This proposes the new idea that wave speed in anchorage medium can be used to calculate consolidation wave speed, and this can make the evaluation of anchorage quality much easier and more accurate because the testing of wave speed in anchorage medium is well developed and reliable and it can be determined by only testing on standard cubic specimens (150 mm Ã 150 mm Ã 150 mm).
Yang C, Sheng D, Carter JP, Sloan SW, 'Modelling the plastic anisotropy of Lower Cromer Till', Computers and Geotechnics, 69 22-37 (2015) [C1]
Â© 2015 Elsevier Ltd. Experimental data on Lower Cromer Till (LCT), a sandy silty-clay, are re-evaluated enabling a study on the effects of plastic anisotropy of soil fabric. The ... [more]
Â© 2015 Elsevier Ltd. Experimental data on Lower Cromer Till (LCT), a sandy silty-clay, are re-evaluated enabling a study on the effects of plastic anisotropy of soil fabric. The results of virgin constant stress ratio consolidation tests reveal that an equilibrium state is achieved and maintained under any specific radial loading path, with characteristics of a unique anisotropic fabric and a unique straining mode. The inclination of the plastic dilatancy and the yield surface from the hydrostatic axis provides a means of quantifying this equilibrium state of the soil fabric. A unique fabric anisotropy at critical state is naturally obtained. Rotational hardening laws are then proposed to quantify the changes in plastic anisotropy of soil fabric for all stress ranges. Constitutive relations are formulated within the framework of Critical Sate Soil Mechanics, with a non-associated flow rule logically determined from experiments. The proposed rotational hardening laws have been systematically validated against a large bank of laboratory tests on LCT samples, covering a variety of deposition conditions, stress histories, and overconsolidation ratios. Comparisons illustrate the feasibility and efficiency of the proposed framework in describing the plastic anisotropy of LCT, which may suggest possible application to other types of clays.
Yang C, Carter JP, Yu S, 'Comparison of model predictions of the anisotropic plasticity of Lower Cromer Till', Computers and Geotechnics, 69 365-377 (2015) [C1]
Â© 2015 Elsevier Ltd. This paper compares predictions, made using selected soil constitutive models, of the anisotropic plastic response of a sandy silty-clay, viz., Lower Cromer ... [more]
Â© 2015 Elsevier Ltd. This paper compares predictions, made using selected soil constitutive models, of the anisotropic plastic response of a sandy silty-clay, viz., Lower Cromer Till (LCT). The performance of four elastoplastic models, designated as MCC (Roscoe and Burland, 1968), S-CLAY1 (Wheeler et al., 2003), SANICLAY14 (Dafalias and Taiebat, 2014) and YANG2015 (Yang et al., 2015), are systematically evaluated based on a series of drained triaxial stress path tests, including virgin constant-stress-ratio (CSR) compression tests, probing stress path tests on initially K < inf > 0 < /inf > consolidated samples, and also various transitional CSR tests. Comparison of the various predictions shows that the isotropic MCC model cannot properly describe the mechanical behaviour of LCT due to its neglect of fabric anisotropy. The other three anisotropic models differ in their definition of the rotational hardening laws, particularly in the description of the equilibrium state of fabric anisotropy achieved under CSR loading. While significant improvements in model predictions can be observed from the three anisotropic models, for LCT S-CLAY1 generally tends to underestimate the volumetric deformation and both S-CLAY1 and SANICLAY14 are likely to overestimate the ratio of the deviatoric and volumetric strains for more anisotropic stress states. YANG2015 exhibits the most consistent performance in reproducing the mechanical behaviour of LCT among the four models under comparison. The importance of the virgin CSR tests to properly understanding the plastic anisotropy of soil fabric is highlighted.
Yang C, Liu X, Liu X, Yang C, Carter JP, 'Constitutive modelling of Otaniemi soft clay in both natural and reconstituted states', Computers and Geotechnics, 70 83-95 (2015) [C1]
Â© 2015 Elsevier Ltd. A rate-independent anisotropic elastoplastic constitutive model for natural soft clays is proposed, with emphasis on the effects of cementation or structure ... [more]
Â© 2015 Elsevier Ltd. A rate-independent anisotropic elastoplastic constitutive model for natural soft clays is proposed, with emphasis on the effects of cementation or structure and fabric anisotropy. The characteristic non-linear normal compression line for structured soils is described by defining a variable compressibility as a function of plastic straining. No reference to the 'intrinsic' reconstituted state is required. The effect of plastic anisotropy is investigated from virgin constant stress ratio consolidation tests, which provide an accurate description of the equilibrium states of soil fabric. The change of fabric anisotropy is correlated with the change of inclination of the yield and plastic potential surfaces via a pair of improved rotational hardening laws. Experiments on Otaniemi clay samples in both natural and reconstituted states are simulated. Comparisons of numerical predictions with experimental data illustrate the feasibility and advantage of the proposed methodology to describe the mechanical behaviour of natural soft clays.
Yang C, Carter JP, Sheng D, 'Description of compression behaviour of structured soils and its application', CANADIAN GEOTECHNICAL JOURNAL, 51 921-933 (2014) [C1]
Yang C, Sheng D, Carter JP, 'Stochastic analysis of hydraulic hysteresis in multi-layer unsaturated soil covers under random flux boundary conditions', Geotechnical Special Publication, 542-554 (2013) [C1]
The effect of hydraulic hysteresis inherent in soil water characteristic curves is explored stochastically in seepage analysis of engineered soil covers. A multi-layer soil cover ... [more]
The effect of hydraulic hysteresis inherent in soil water characteristic curves is explored stochastically in seepage analysis of engineered soil covers. A multi-layer soil cover with random top boundary flux conditions is simulated with the First Order Second Moment method. Water inflow and outflow at the top boundary are chosen as two random variables. The capillary barrier mechanism is taken into account, and the breakthrough hydraulic head at the bottom boundary of the soil cover is adopted as the performance function. Results show that the hysteretic hydraulic model predicts a more conservative result than does the traditional nonhysteretic hydraulic model when simulating seepage in unsaturated, multi-layer soil covers. The dependence of the soil cover performance on its exterior environment during construction is also identified, with a relatively arid season significantly improving the soil cover's functionality. Furthermore, multi-layer soil covers with a proper selection of geotechnical materials provide better performance than a single layer of soil cover of the same thickness. The importance of hydraulic hysteresis in soil covers subjected to alternative climatic actions is emphasized. Â© 2013 American Society of Civil Engineers.
Yang C, Sheng D, Carter JP, Huang J, 'Stochastic Evaluation of Hydraulic Hysteresis in Unsaturated Soils', JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING, 139 1211-1214 (2013) [C1]
Wang SY, Sun L, Yang C, Yang SQ, Tang CA, 'Numerical study on static and dynamic fracture evolution around rock cavities', Journal of Rock Mechanics and Geotechnical Engineering, 5 262-276 (2013) [C1]
Yang C, Sheng D, Carter JP, 'Effect of hydraulic hysteresis on seepage analysis for unsaturated soils', Computers and Geotechnics, 41 36-56 (2012) [C1]
Sheng D, Yang C, 'Discussion of fundamental principles in unsaturated soil mechanics', Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering, 34 438-456 (2012) [C1]
|Show 17 more journal articles|
Conference (6 outputs)
Yang C, Carter JP, Sheng D, 'On the compression behaviour of structured soils', Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014 (2015) [E1]
Structured soils exhibit an apparent non-linear normal compression line in the semi-log compression plane, which dominates the difference in the mechanical behaviour between struc... [more]
Structured soils exhibit an apparent non-linear normal compression line in the semi-log compression plane, which dominates the difference in the mechanical behaviour between structured soils and their reconstituted counterparts. The effect of soil structure is investigated via the change of compression stiffness with structure degradation. A differential expression of the normal compression line is then established and applied to a large number of different types of soil. Satisfactory results are obtained, illustrating the validity and applicability of the proposed approach. Â© 2015 Taylor & Francis Group, London.
Yang C, Yang CS, Liu XF, 'An improved modeling of hydro-mechanical behavior of unsaturated compacted soils', Unsaturated Soils: Research and Applications (2014) [E1]
Yang C, Sheng D, Carter JP, Pineda J, Kelly R, 'From compression behavior to plastic anisotropy of reconstituted soft soils', Geotechnical Special Publication (2014) [E1]
The plastic anisotropy of reconstituted soft soils is described from the compression behaviour observed during radial loading paths in stress space. A unique relationship is estab... [more]
The plastic anisotropy of reconstituted soft soils is described from the compression behaviour observed during radial loading paths in stress space. A unique relationship is established between the orientation of the yield surface and the corresponding normal compression line, which indicates that a stabilized fabric is maintained under continuous loading along radial stress paths. The equilibrium orientation angle of the plastic potential surface is obtained explicitly. A new rotational hardening law is proposed by considering the dependence of the evolution of anisotropic fabric with the current stress condition and plastic strain. An elastoplastic constitutive model for anisotropic soil is formulated within the framework of Critical State Soil Mechanics. Validation with experimental data and predictions from other models demonstrate the feasibility of the basic concept and the capacity of the proposed new model. Â© 2014 American Society of Civil Engineers.
Yang C, Huang MS, Cui Y-J, 'Constitutive model of unsaturated structured soils under cyclic loading', Proceedings of the Fifth International Conference on Unsaturated Soils (2011) [E1]
Yang C, Sheng D, Carter JP, 'Numerical modelling of hydraulic hysteresis in unsaturated soil covers', Computer Methods for Geomechanics: Frontiers and New Applications. Volume 2 (2011) [E1]
Yang C, Sheng D, Carter JP, 'Hysteretic seepage analysis in unsaturated soil covers', Unsaturated Soils: Theory and Practice (2011) [E1]
|Show 3 more conferences|
Dr Chao Yang
Centre of Geotechnical and Material Modelling
School of Engineering
Faculty of Engineering and Built Environment
|Phone||(02) 4985 4996|
Callaghan, NSW 2308