Effect of heating on the excess pore water pressure of clay under undrained condition
WANG Kuanjun1，2，HONG Yi1，2，WANG Lizhong1，2，LI Lingling1，2
(1. College of Civil Engineering and Architecture，Zhejiang University，Hangzhou，Zhejiang 310058，China；2. Key Laboratory of Offshore Geotechnics and Material of Zhejiang Province，Zhejiang University，Hangzhou，Zhejiang 310058，China)
Abstract：Both the nuclear waste container and energy pile buried underground will elevate the temperature and change the stiffness and strength of the surrounding soil，leading to the possible deformation and potential instability of the geo-structure. Despite the extensive investigations into the effects of heating on mechanical behaviour of clay under drained condition，little attention has been paid to the influence of heating on the clay under undrained condition，which is frequently encountered in practice. This paper aims to study the pore pressure response of clay due to undrained heating through both theoretical and experimental investigations. A simplified model base on the framework of critical state soil mechanics was formulated to predict the development of the excess pore pressure of clay due to heating. Two types of clay(Zijingang clay and kaolin clay) were investigated experimentally using a temperature-controlled GDS triaxial testing apparatus. It was shown that the positive excess pore pressure was induced in both normally consolidated and overconsolidated clays subjected to undrained heating. The excess pore pressure increased with the temperature elevation，but decreased with the over-consolidation ratio(OCR). For the normally consolidated clay heated from 20 ℃ to 55 ℃，each temperature increment of 10 ℃ led to a 10% reduction in the effective stress. When the OCR exceeded 10，the heating induced excess pore pressure was almost negligible. The calculated results using the proposed model agreed reasonably with the experimental data，confirming the validity of the proposed model .
王宽君1，2，洪 义1，2，王立忠1，2，李玲玲1，2. 不排水升温条件下黏性土孔压响应[J]. 岩石力学与工程学报, 2017, 36(9): 2288-2296.
WANG Kuanjun1，2，HONG Yi1，2，WANG Lizhong1，2，LI Lingling1，2. Effect of heating on the excess pore water pressure of clay under undrained condition. , 2017, 36(9): 2288-2296.
[1] YAO Y P，ZHOU A N. Non-isothermal unified hardening model：a thermo-elasto-plastic model for clays[J]. Géotechnique，2013，63(15)： 1 328–1 345.
[2] CAMPANELLA R G，MITCHELL J K. Influence of temperature variations on soil behaviour[J]. Journal of the Soil Mechanics and Foundations Division，ASCE，1968，94(3)：709–734.
[3] ERIKSSON L G. Temperature effects on consolidation properties of sulphide clays[C]// Proceedings of the 12nd International Conference of Soil Mechanics and Foundation Engineering. [S. l.]：[s. n.]，1989：2 087–2 090.
[4] TIDFORS M，SALLFORS G. Temperature effect on preconsolidation pressure[J]. Geotechnical Testing Journal，1989，12(1)：93–97.
[5] HUECKEL T，BALDI G. Thermoplasticity of saturated clays：experimental constitutive study[J]. Journal of Geotechnical and Geoenvironmental Engineering，1990，116(12)：1 778–1 796.
[6] TOWHATA I，KUNTIWATTANAKUL P，SEKO I，et al. Volume change of clays induced by heating as observed in consolidation tests[J]. Soils and Foundations，1993，33(4)：170–183.
[7] KUNTIWATTANAKUL P，TOWHATA I，OHISHI K，et al. Temperature effects on undrained shear characteristics of clay[J]. Soils and Foundations，1995，35(1)：147–162.
[8] MORITZ L. Geotechnical properties of clay at elevated temperatures[M]. Linköping：Swedish Geotechnical Institute，Linköping，Roland Offset，1995：41–44.
[9] TANAKA N. Thermal elastic plastic behaviour and modelling of saturated clay[Ph. D. Thesis][D]. Winnipeg，Man：University of Manitoba，1995.
[10] LALOUI L，CEKEREVAC C. Thermo-plasticity of clays：an isotropic yield mechanism[J]. Computers and Geotechnics，2003，30(8)：649–660
[11] ABUEL-NAGA H M，BERGADO D T，LIM B F. Effect of temperature on shear strength and yielding behaviour of soft Bangkok clay[J]. Soils and Foundations，2007，47(3)：423–436.
[12] ABUEL-NAGA H M，BERGADO D T，BOUAZZA A，et al. Volume change behaviour of saturated clays under drained heating conditions：experimental results and constitutive modeling[J]. Canadian Geotechnical Journal，2007，44(8)：942–956.
[13] HUECKEL T，BORSETTO M. Thermoplasticity of saturated soils and shales：Constitutive equations[J]. Journal of Geotechnical and Geoenvironmental Engineering，1990，116(12)：1 765–1 777.
[14] CUI Y J，SULTAN N，DELAGE P. A thermomechanical model for saturated clays[J]. Canadian Geotechnical Journal，2000，37(3)：607–620.
[15] BALDI G，HUECKEL T，PEANO A，et al. Developments in modelling of thermo-hydro-geomechanical behaviour of Boom clay and clay-based buffer materials[R]. Report EUR13365，Commission of the European Communities. Nuclear Science and Technology，Luxembourg：Bernan Press，1991.
[16] ABUEL-NAGA H M，BERGADO D T，BOUAZZA A，et al. Thermomechanical model for saturated clays[J]. Géotechnique，2009，59(3)：273–278.
[17] WANG L Z，WANG K J，HONG Y. Modeling temperature-dependent behavior of soft clays[J]. Journal of Engineering Mechanics，2016，142(8)：04016054.
[18] MONFARED M，SULEM J，DELAGE P，et al. On the THM behaviour of a sheared Boom clay sample：application to the behaviour and sealing properties of the EDZ[J]. Engineering Geology，2012，124(1)：47–58.
[19] POLEVOY S L. Water science and engineering[M]. London，UK：Chapman and Hall，1996：15–43.
[20] SULTAN N，DELAGE P，CUI Y J. Temperature effects on the volume change behaviour of Boom clay[J]. Engineering Geology，2002，64(2/3)：135–145.
[21] CEKEREVAC C，LALOUI L. Experimental study of thermaleffects on the mechanical behaviour of a clay[J]. International Journal for Numerical and Analytical Methods in Geomechanics，2004，28(3)：209–228.
2017, Vol. 36 
