Discussion on Two Simplified Swelling Pressure Models for Expansive Soils   Jia Jing-chao Institute of Geotechnical Engineering, School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian, China jjcdut@yahoo.cn Yang Qing School of Civil and Hydraulic Engineering and The State Key Lab. of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China qyang@dlut.edu.cn Luan Mao-tian School of Civil and Hydraulic Engineering and The State Key Lab. of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China Li Qiang Institute of Geotechnical Engineering, School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian, China
			ABSTRACT

The swelling pressure model developed by former researchers based on the Gouy-Chapmann interacting diffuse double layer theory and osmotic pressure theory is effective in simulating swelling pressure of expansive soils. But it is difficult to combine equations of the model to calculate swelling pressure directly from void ratio because one of the equations is elliptic integral. So some researchers proposed the best-fit linear equation for the parameters u and Kd in the elliptic integral and then presented simplified swelling pressure model composed of the best-fit linear equation and other equations. However, when the range of Kd is big, the linear relationship does not fit u-log(Kd) well. Here the second order exponential function is applied to fit u-Kd relationship, and the results indicate that it fits u-Kd exactly without the influences of the range of Kd and other factors. At last, based on the u and Kd values obtained by numerical integration of the interacting double layer model and the second order exponential function for u-Kd, the feasibility to use the single double layer theory to establish swelling pressure model is discussed.

Keywords: Expansive soils, Swelling pressure model, u-Kd relationship, Second order exponential function, Single double layer theory

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