| Loess is loose and porous,the vertical joints are well developed,and it would disintegrate when soaking water.The loess gulley,loess cave and loess landslide are widely developed in loess areas,which formation process was related to the loess disintegration.The disintegration characteristics of loess would have great significance in geological hazard prevention and controlling.Based on study on the rock-soils disintegration of the domestic and foreign scholars,loess disintegpration is analyzed relied on the national "12th Five-Year Plan" science and technology support topics called"control technology and demonstration research of landslide in Heifangtai Gansu Province".Firstly,loess disintegration characteristics are studied through in-situ submerging disintegration test for loess samples of the different shapes.Then,series of disintegration experiments for loess of Heifangtai are tested by the reconstructive disintegration instrument.Four impact factors are selected with variable-controlling approach to test disintegration,which includes sample size,initial moisture content,water temperature and salinity.Then,the main controlling factors of disintegration are studied by comparing with the loess disintegration characteristics of different areas.Finally,loess disintegration mechanism and disaster mechanism can be analyzed based on field investigation and disintegration tests.The results show that as follow:(1)The disintegration process of loess can be divided into three stages including water absorption stage,softening stage and collapsing stage,especially the disintegration is main in third stage because of shorter the duration of first two stages,(2)The typical curve of disintegration is " S" shape,up and down trend of curve may reflect rate of disintegration,but the disintegration mainly occurs in the intermediate stage of curve,and the disintegration is relatively stable in this stage,the relationship between disintegration rate and various variable is fitted with average disintegration rate of the intermediate stage of curve.(3)The disintegration is affected by the shape,the size,the wetted surface of samples and so on.The disintegration velocity are positively correlated with water temperature but negatively correlated with sample size and initial moisture content.And there is smaller effect on salinity.By using the grey correlation analysis,relating degree of water content is highest,next is soil sample size,then is water temperature.(4)The loess disintegration characteristics are closely related to own structure,particle composition and cement. |
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