Modelling frost heave in unsaturated coarse-grained soils
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RESEARCH PAPER
Modelling frost heave in unsaturated coarse-grained soils Jidong Teng1 • Jianlong Liu1 • Sheng Zhang1 • Daichao Sheng1,2 Received: 30 July 2019 / Accepted: 16 March 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Coarse-grained soils were considered not susceptible to frost heave. However, substantial frost heave has been observed in unsaturated coarse fills in high-speed railway embankments. Recent experimental results in the literature show that vapour transfer has a considerable influence on the frost heaving of coarse-grained soil. However, vapour transfer has rarely been considered in modelling frost heave. This study presents a new frost heave model that considers vapour transfer and its contribution to ice formation. An updated computer program (PCHeave) is developed to account for the vapour transfer in unsaturated coarse-grained soils, where the rigid ice theory is applied to initiate ice lens formation in the frozen fringe. The results of the proposed model are compared with laboratory test results, which show reasonable agreement. The frost heave data monitored in 2013–2014 along the embankment of the Harbin–Dalian Passenger Dedicated Railway are also used to validate the proposed model. The prediction of the model agrees well with the measured results of frost heave and frost depth. This indicates that the proposed model can reasonably reflect the process of frost heave caused by vapour transfer in unsaturated coarse-grained soils. Keywords Frost heave Numerical model Unsaturated coarse-grained soil Vapour transfer List of symbols dxf/dt The advancing rate of the frost front xf or the frost penetration rate during Dt and is negative when frost advances downwards (m/s) r The total stress or the total overburden pressure (Pa) 0 r The effective stress (Pa) n The soil porosity I The ice content Mean ice content in the current frozen fringe I Ib The current volumetric ice content at xb uw The pore water pressure (Pa) ui The pore ice pressure (Pa) un The neutral stress (Pa) qw The density of liquid water (g/cm3) qi The density of ice (g/cm3)
& Sheng Zhang [email protected] 1
2
National Engineering Laboratory for High-Speed-Railway Construction, Central South University, Railway Campus of Central South University, Shaoshan South Road No. 68, Changsha 410075, Hunan Province, China School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, Australia
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xf xb xw T0 Tc Tf Ts Tw Vi L
Density of vapour (g/cm3) Effective thermal conductivity of the layer above xb (W/(m °C) Effective thermal conductivity of the current frozen fringe (W/(m °C) Effective thermal conductivity of the unfrozen zone between xf and xw (Fig. 1) (W/(m °C) Thermal conductivity of a soil saturated by water and ice (W/(m °C) Thermal conductivity of the dry soil (W/(m °C) Either the cold boundary of the soil profile for coarse calculation or the location of the cold boundary of the growi
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