Study On Soil-water Characteristics And Crack Development Of Dry-wet Circulation Red Soil

This article is based on the alternating drought and deluge weather condition and choose the dam clay widely spread in Yun Nan Province as the object of study so as to propose the task of ‘the study of the characteristic of clay-water of the laterite under drying and wetting cycle and its crevice's development'.Taking the times of drying and wetting cycle,the humidifying time,dehumidifying time,initial dry density and initial moisture content into consideration,through the methods of filter paper test,wetting-drying test and microstructure test,this paper has studied the clay-water characteristic of laterite,the development characteristic of its crevice,its microstructure characteristic under different experiment conditions.And this paper has propose the mechanism of how the drying and wetting cycle will damage the experimental project.The experiment of the clay-water characteristic of laterite under drying and wetting cycle showing: The base material's attraction will decrease along with the increase of the moisture content in dehumidifying time,will increase along with the increase of the dry density and will decrease along with the increase of the times of dehumidification.However,in the humidifying time,the attraction will decrease when the moisture content increase,the humidification times will not bring too much effect to it.The characteristic curve of the clay-water has the hysteresis effect.And the hysteresis loop will decrease when the drying and wetting cycle times increase.Comparing with the pressure plate apparatus,the attraction of the base material's range will be larger through filter paper test.The research of the crevice characteristic under different dry density in drying and wetting cycle showing: Along with the humidifying time's extension,the crevice will show a concave change and it will close at first then extend.The crevice characteristic will increase along with the increase of humidifying times.However the crevice will show a convex change along with the dehumidification time's extension and it will extend at first and then close.The time of concave change reaching its peak point will decrease when the dehumidification times increase.The microstructure test shows that the microstructure will change more obvious when the dry density becomes bigger and the characteristic parameters of microstructure will be opposite in low and high magnification.The larger the initial dry density is,the more asymmetrical the moisture content and the expansion will be,and the craze will be more serious.The study of the crevice characteristic under different moisture content in drying and wetting cycle showing: When the initial moisture content is bigger the samples is easier to break.And the time spending on crevice characteristic parameters reaching its peak point will be shorter when there are more cycling times,the contracted stable time will be shorter as well.The microstructure change will be more significant when the initial moisture content is higher.As for the samples with higher initial moisture content because its thickness of free water surface film is thicker,it will bring effect to the cementation effect of the soil and lead to the heavily break of it.