Steps For Civil, Constructions and Environmental Engineering

Employing Numerical Modelling to Calculate Changes in Safety Factors for The Bearing Capacity of Expansive Clay Soil Subjected to Cycles of Full Wetting and Partial Drying

Rodina Daod

Department of Geotechnical Engineering, Faculty of Civil Engineering, Damascus University, Syria.

Nazih Abboud

Department of Geotechnical Engineering, Faculty of Civil Engineering, Damascus University, Syria.

Mohamad Imad Machlah

Department of Geotechnical Engineering, Faculty of Civil Engineering, Damascus University, Syria.

DOI: https://doi.org/10.61706/sccee120119

Keywords: Modelling, Safety Factors, Bearing Capacity, Wetting Drying Cycles, Expansive Soil

---

Abstract

Soil mechanics provides a theoretical framework for understanding the behaviour of soil in relation to structures and the extent to which it is influenced by various natural and unnatural factors. A series of laboratory experiments on soil are conducted in its current condition, without consideration of potential long-term changes to its specifications and behaviour. Furthermore, the implications of these changes on the most crucial soil calculations, namely bearing capacity and safety factors, are not addressed. This prompted us to emphasise the potential risks associated with the failure to consider the changes that occur in clay soils. In this research, the findings of prior experiments on expansive soils subjected to cycles of complete wetting and partial drying were used as a basis for numerical modelling using the MATLAB program. This resulted in the derivation of mathematical equations that express the changes with the number of cycles. The Hansen relationship was employed for the calculation of the bearing capacity of the soil, as well as for the determination of the safety factors. A clear decline was observed in the bearing capacity values for the various soil types under investigation. Additionally, a notable reduction in safety factor values was identified, with some soils exhibiting a decrease exceeding 40%. This is a significant concern due to the potential for substantial material and human losses. It was thus imperative to consider the impact of wetting and drying cycles when conducting laboratory experiments to ascertain the actual safety factors in structures.

---

References

Abboud, N., Machlah, M., & Daod, R. O. (2023). Study of changes in the stress condition and void ratio of expansive soils subjected to the wetting and drying cycles. Damascus University Journal of Engineering Sciences.

Abdurrahman, H., &Al Zubaydi, T. (2011). Effect of Wetting and Drying Cycles on Swell/Collapse Behavior and Cracks of Fine – Grained Soils. Tikrit Journal of Engineering Sciences,18(4), 71-79. https://doi.org/10.25130/tjes.18.4.08

Al-Homoud, A., Basma, A., & Malkawi, H.A. )1995(. Cyclic swelling behaviour of clays. Journal of Geotechnical Engineering, 121(7), 526-565. https://doi.org/10.1061/(ASCE)0733-9410(1995)121:7(562)

Al-Houri, H. (2018). Introduction to the MATLAB system.

Allam, M., Sridharan, A. (1981). Effect of wetting and drying on shear strength. Journal of the Geotechnical Engineering Division, 107 (4), 421-438. https://doi.org/10.1061/AJGEB6.0001117

Al-Muhaidib, A. (2002). Properties of expansive soil in the Kingdom of Saudi Arabia. King Saud University, Riyadh.

Alonso, E., Vaunat, J., &Gens, A. (1999). Modelling the mechanical behavior of expansive clays. Elsevier Science. Engineering Geology ,54, 173–183. https://doi.org/10.1016/S0013-7952(99)00079-4

Al-Swaidani, A., Hammoud, I., &Meziab, A. (2016). Effect of adding natural pozzolana on geotechnical properties of lime-stabilized clayey soil. Journal of Rock Mechanics and Geotechnical Engineering. (5), 714-725. https://doi.org/10.1016/j.jrmge.2016.04.002

Bilsel, H., & Tuncer, E.R. (2017). Cyclic swell-shrink behaviour of Cyprus clays. Eastern Mediterranean University. North Cyprus.

Braja, Das. (2010). Principles of Geotechnical Engineering. Seventh Edition

Brigatti, M., Galan, E., & Theng, B. K. (2006). Hand Book of Clay Science. Structures and Mineralogy of Clay Minerals, Elsevier, (1), 19-86. https://doi.org/10.1016/S1572-4352(05)01002-0

Chen, F. (1988). Foundations on Expansive Soils. Elsevier Scientific Publishing Company. (1). 295.

Estabragh, A., Parsaei, n., & Javadi.A.(2015). Laboratory investigation of the effect of cyclic wetting and drying on the behaviour of an expansive soil. The Japanese Geotechnical Society. Elsevier. 55(2), 304–314. https://doi.org/10.1016/j.sandf.2015.02.007

Hossain, S., wei, K., & Song, Y. (2016). Effect of drying – wetting cycles on saturated shear strength of undisturbed residual soils. American Journal of Civil Engineering. (4), 156-166. https://doi.org/10.11648/j.ajce.20160404.15

Li, X., Liang, Y., Zhang, P., & Wang, Y. (2010). Research into Treatment Theory and Technique for Expansive Soil Geological Disasters. Memoirs of the Muroran Institute of Technology. (59), 165-171.

Medjnoun, A., & Bahar, R. (2016). Shrinking–swelling of clay under the effect of hydric cycles. Springer International Publishing Switzerland. 46. https://doi.org/10.1007/s41062-016-0043-6

Naeini, S., Gholampoor, N., & NajmosadatyYazdy, S. (2015). The Effect of Wetting-Drying Cycles and Plasticity Index on California Bearing Ratio of Lime Stabilized Clays. Journal of Engineering Geology, 9(2), 2817. https://doi.org/10.18869/acadpub.jeg.9.2.2817

Rogers, L., & Wright, S. (1986). The effects of wetting and drying on the long – term shear strength parameters for compacted Beaumont clay. The University of Texas at Austin. Texas, (133).

Sharma, R., Gehlot, J., Sindhal, A., & Laddha, A. (2017). Impact of Cyclic Wetting and Drying on Swelling Behaviour of Stabilised and Non-Stabilized Soil- A Review Study. International Journal of Advance Engineering and Research Development. 4 (12), 546. https://doi.org/10.21090/IJAERD.98651

Vinod, P., & Bindu, J. (2010). Compression Index of Highly Plastic Clays – an Empirical Correlation. Indian Geotechnical Journal, 40(3), 174-180.

Yeni, H. (1988). Soil Mechanics. Damascus university. Faculty of Civil Engineering.

Zeng, Z., Lu, h., Zhao, y., & Qin, y. (2020). Analysis of the mineral compositions of swell—shrink clays from guangxi province, chine. Clays and Clay Minerals. spring. (68), 161–174. https://doi.org/10.1007/s42860-019-00056-7