冻融循环作用下盐渍土病害机理及改良技术综述

盐渍土在冻融循环作用下，主要表现出盐胀和冻胀特性，对土体结构造成破坏，土体发生变形，从而降低土体强度，给工程建设造成危害。为改良盐渍土、防治盐渍土病害，从盐渍土病害产生的机理出发，介绍了结晶压力是导致土体结构发生破坏、土体发生变形的本质因素，证实了结晶压力的大小与孔隙大小有关。水盐迁移会加剧盐胀和冻胀的发生。在冻融循环作用下，水分和盐分向土体表层发生运移。盐渍土的盐－胀特性受土体的干密度、含水量、含盐量、荷载和温度的影响，不同因素的影响程度不同，干密度的影响较含水量小。干密度越大、含水量和含盐量越高、降温速率越慢，盐－冻胀越强烈。荷载对盐－冻胀有抑制作用。通过对盐渍土病害机理的研究，结合盐渍土盐－冻胀的影响因素，从土质改良、加固土体、阻断水盐通道和温度控制四个方面阐述了冻融作用下盐渍土的改良方法，可供盐渍土地区的工程建设参考。目前关于结晶压力的研究主要是定性方面的，水盐迁移的研究以室内试验为主。未来对盐渍土病害机理的研究将主要集中在结晶压力的定量研究和水盐迁移的现场试验等方面。

Overreview on disease mechanism and improvement technology of saline soil under effect of freeze-thawing cycle

Under of freeze-thawing cycle，saline soil mainly shows the characteristics of salt heave and frost heave，which damages the soil structure and deforms the soil，thus reducing the soil strength and causing harm to the engineering construction． In order to improve saline soil as well as prevent and control saline soil disease，it is introduced herein from the aspect of the mechanism of the causation of saline soil disease that the crystallization pressure is the essential factor to cause the damage and the deformation of soil mass structure，and then it is confirmed that the magnitude of the crystallization pressure is related to the pore size． The water-salt migration can intensify the occurrences of salt expansion and frost heaving． Under the freeze-thawing effect， water and salt migrate to the surface of soil． The salt expansion characteristics of saline soil is impacted by the dry density，the water content，the salt content，the load and the temperature of the soil mass，from which the impacting degrees from different factors are different，while the impact from the dry density is less than that from the water content． The larger the dry density is and the higher the water content and the salt content are，the lower the rate of temperature fall is to be and the more intensive the salt-frost heaving is to be as well． Load has a restraining effect on the salt-frost heaving． Through the study made on the mechanism of the saline soil disease，the methods for improving the saline soil under the freeze-thawing effect are expounded in combination with the impacting factors of the salt-frost-heaving from four aspects，i． e． soil improvement，reinforcement of soil mass， water-salt channel blocking and temperature control，which can provide a certain reference for the construction of the project within saline soil region． At present，the studies on the crystallization pressure mainly focus in the qualitative aspect，while the study on the water-salt migration is mainly based on lab-experiment． The studies on the mechanism of the saline soil disease are to mainly focus in the aspects of the quantitative study of crystallization pressure，the in situ experiment on water-salt migration，etc．