Experimental study on deformation of remolded sulfate saline soil under freeze-thaw cycles北大核心CSCD

季节冻土区特殊的温湿环境造成盐渍土累积变形是导致众多工程问题的主要原因，但其变形破坏机理尚不十分明确。通过配制不同含盐量的粉土开展冻融循环试验，研究试验过程中温度、未冻水含量、孔隙水压力、基质吸力和位移的变化规律。结果表明：孔隙水压力和基质吸力对土体温度敏感，对土体变形有重要影响。类比于非饱和土有效应力原理，给出了冻结盐渍土的有效应力方程，将土体变形分为温度应变、盐胀、冻胀、溶陷、融沉和残余应变，很好地解释了冻结盐渍土的变形机理。研究了含盐量对土体变形的影响程度，发现低含盐量时土体应变以冻胀和融沉为主；随着含盐量的增加，盐胀和溶陷的贡献越来越大；而含盐量为1%时土体变形最小，表明适当控制含盐量可有效抑制土体变形。

Experimental study on deformation of remolded sulfate saline soil under freeze-thaw cycles

The accumulated deformation of saline soil caused by the special temperature and humidity environment is the main cause of numerous engineering problems in seasonally frozen region. However， the deformation failure mechanism of saline soil is not well defined. The freeze-thaw cycle experiments are carried out by silt with different salt contents to investigate the variation characteristic of temperature， unfrozen water content， pore water pressure， matric suction and displacement during the test. It is found that the pore water pressure and matric suction are sensitive to soil temperature and have important effects on soil deformation. By analogy with the effective stress principle of unsaturated soil， the effective stress equation of frozen saline soil is given. The soil deformation is divided into temperature strain， salt expansion， frost heave， dissolve collapse， thaw settlement and residual strain， which completely explains the deformation mechanism of frozen saline soil. Moreover， the degree of influence of salt content on soil deformation is discussed， which indicates that frost heave and thaw settlement are the main strains of saline soil with low salinity. With the increase of salt content， the contribution of salt expansion and dissolve collapse becomes more and more significant. The soil deformation is minimum when the salt content is 1%， which indicates that proper control of salt content can effectively suppress soil deformation.