Development of a Constitutive Model for Clays Based on Disturbed State Concept and Its Application to Simulate Pile Installation and Setup
In this paper, an elastoplastic model is proposed to describe the behavior of clayey soils subject to disturbance at the soil-structure interaction for application to pile installation and the following setup. The soil remolding that occurs during deep penetration and the following soils thixotropic strength regaining over time were modeled in this study. The disturbed state concept (DSC) was used as a core of the proposed model, and the critical state theory was adopted to define the main components for the DSC model. The Modified Cam-Clay (MCC) model was implemented within the context of DSC to define the intact state response. A novel approach was applied to define the soil shear response for the MCC model to have it applicable in DSC. Furthermore, the soil remolding during shear loading was related to the deviatoric plastic strain developed in the soil body. The proposed model, referred as Critical State and Disturbed State Concept (CSDSC) model, can capture the elastoplastic behavior of both NC and OC soils. The proposed model was implemented in Abaqus software, and it was then validated using the triaxial test results available in the literatures. Very good agreement was obtained between the triaxial test results and the CSDSC model prediction for different stress paths, stress-strain response and the generated excess porewater pressures. Furthermore, pile installation and the following pile setup behavior were modeled using the proposed CSDSC model. The predicted values for pile resistance using CSDSC model were compared with the values measured from field load tests, which indicated that the proposed model is capable of simulating pile installation and predict appropriately the pile capacity as well as the disturbance behavior at the soil body.
KeywordsElastoplastic constitutive model Soil thixotropy CSDSC Disturbed state concept Critical state theory Hardening and softening Triaxial test
This research is funded by the Louisiana Transportation Research Center (LTRC Project No. 11-2GT) and Louisiana Department of Transportation and Development, LADOTD (State Project No. 736-99-1732).
- Basu, P., Prezzi, M., Salgado, R., Chakraborty, T.: Shaft resistance and setup factors for piles jacked in clay. J. Geotech. Geoenviron. Eng. 140(3) (2014)Google Scholar
- Desai, C.S.: Mechanics of Materials and Interface: The Disturbed State Concept. CRC Press, Boca Raton (2001)Google Scholar
- Fakharian, K., Attar, I.H., Haddad, H.: Contributing factors on setup and the effects on pile design parameter. In: Proceedings of 18th International Conference on Soil Mechanics and Geotechnical Engineering, Paris (2013)Google Scholar
- Haque, M.N., Abu-Farsakh, M., Chen, Q., Zhang, Z.: A case study on instrumentation and testing full-scale test piles for evaluating set-up phenomenon. In: 93th Transportation Research Board Annual Meeting, vol. 2462, pp. 37–47 (2014)Google Scholar
- Likitlersuang, S.: A hyperplasticity model for clay behavior: an application to Bangkok clay. Ph.D dissertation, The University of Oxford (2003)Google Scholar
- Ling, H., Yue, D., Kaliakin, V., Themelis, N.: Anisotropic elastoplastic bounding surface model for cohesive soil. J. Eng. Geomech. 7, 748–758 (2002)Google Scholar
- Mitchell, J.K.: Fundamental aspects of thixotropy in soils. J. Soil Mech. Found. Des. 86, 19–52 (1960)Google Scholar
- Roscoe, K.H., Schofield, A.N.: Mechanical behavior of an idealized wet clay. In: Proceedings of 2nd European Conference on Soil Mechanics and Foundation Engineering, Wiesbaden, vol. 1, pp. 47–54 (1963)Google Scholar
- Roscoe, K.H., Burland, J.B.: On the Generalized Behavior of Wet Clay, Engineering Plasticity, pp. 535–610. Cambridge University Press, Cambridge (1968)Google Scholar
- Shao, C.: Implementation of DSC model for dynamic analysis of soil-structure interaction problems. Ph. D. Dissertation. Dept. of Civil Engineering, University of Arizona, Tucson, Arizona (1998)Google Scholar
- Wathugala, G.W.: Finite element dynamic analysis of nonlinear porous media with application to the piles in saturated clay. Ph. D. Dissertation. Dept. of Civil Engineering, University of Arizona, Tucson, Arizona (1990)Google Scholar