Study On The Formation Mechanism Of Loess Collapse Induced By Rainfall In Yan'an Area

Loess Collapse is the most common and dangerous geotechnical hazard in Yan'an Area.According to scientific research,the rainfall infiltration is the main factor which induces the loess collapse hazard.The main research content is the formation mechanism of loess collapse induced by rainfall.Through the investigation of the loess collapse slope in yan'an are,the main influence factors of the loess collapse were researched.Based on the dry-wet circle experiment,the variation law of shear strength and loess fissures influenced by dry-wet circle was researched.According to the saturated-unsaturated seepage theory and unsaturated soil shear strength theory,the influence law of loess strength and loess slope stability induced by rainfall was researched.By the stability coefficient calculation formula of loess collapse,the influence law of stability coefficient was discussed.Based on the Geo-Slope Software analysis,the loess collapse mechanism influenced by the rainfall intensity was researched.Through the scientific research,this paper achieved the following results.The internal factor of the loess collapse are the loess property,jont fissure and slope form.The external factor of the loess collapse are the rainfall infiltration,freeze-thaw action and the human engineering activity.Under the action of dry-wet circle,the cohesion and internal friction angle of loess decrease.The infiltration mechanical action of rainfall will decrease the shear strength of loess.By the increase of rainfall intensity and rainfall capacity,the loess matric saction,shear strength and slope stability will decrease.For the action of loess fissures,the shear strength of loess decrease which lead to the occurrence of loess collapse.