A Calculation Method of Thermal Pore Water Pressure Considering Overconsolidation Effect for Saturated Clay

Abstract

With the increase of soil consolidation degree, the pore water pressure induced by thermal loading drops dramatically. To conveniently and quickly calculate the thermal pore water pressure inside the soil under different overconsolidation states and quantify overconsolidation effect on thermal pore water pressure, a calculation method of thermal pore water pressure considering overconsolidation effect for saturated clay is proposed. The method is verified by the relevant experimental data, and good agreements were achieved. Through analyzing the influence mechanism of OCR on the thermal pore water pressure, three important findings were captured. (1) For overconsolidated clay, thermal pore water pressure decreases nonlinearly with the increase of OCR. (2) There is a critical threshold of OCR 4.3; when 1 < OCR ≤ 4.3 (slightly overconsolidated state), the ratio of compression line slope to recompression line slope (Λ) of overconsolidated clay is consistent with that of the normally consolidated clay, while when OCR > 4.3 (highly overconsolidated state), the value of Λ is smaller than that of normally consolidated clay. (3) For highly overconsolidated clay (OCR > 4.3), considering the reducing of Λ with OCR, the prediction accuracy of the thermal pore pressure calculation method has been greatly improved; especially when OCR equals 30, the prediction accuracy improves by 92.7% as temperature change achieves 35 °C.