底部掏蚀区的形成和发展是干旱区受环境因素控制最为典型和危害最为普遍的土遗址病害之一,通过对河西走廊沿线12市县明长城遗址掏蚀区形态、盐分、干湿条件及风场特征的调查、监测与分析,发现了遗址阴阳坡掏蚀区的形态、含盐状态、风场条件和降雨过程中的温湿度变化均存在显著差异;并结合室内实验条件下脱盐后分别掺入不同含量NaC1和Na2SO4并经历3、6、9、12次干湿循环养护的遗址土重塑试样的风洞模拟实验,提出干旱地区土遗址阴阳坡掏蚀区差异效应,揭示了盐分类型与含量、干湿循环次数、挟沙风风速和吹蚀时间对土遗址阴阳坡掏蚀区差异效应的影响,最后结合调查分析和实验结果对其形成机理进行了初步讨论.%The formation and development of bottom undercutting area are one disease of soil sites,which is the most typical and common disease affected by environmental.This paper investigates,monitors and analyses the morphology,salinity,dry-wet conditions and wind field characters of the Great Wall on Ming Dynasty ruins in 12 cities along the Hexi Corridor.It finds that the morphology,salinity,wind field characters and temperaturehumidity change in the process of rainfall are significantly different at the site of shady and sunny slopes of the undercutting area.Based on the results of wind tunnel simulation experiment,in which remodeling samples desalinated and mixed with different contents of NaCl and Na2SO4 and undergoing 3,6,9,12 dry-moisture cycles,differential effect in the site of shady and sunny slopes of the undercutting area of earthen ruins in arid region is proposed.It also reveals the influences of salt type and content,number of wet and dry cycles,wind velocity and time of blowing on differential effect.Finally,the formation mechanism of differential effects is discussed with the results of investigation analysis and experiment.
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