Mechanism And Stability Analysis Of Loess Landslide Induced By Groundwater

This paper relies on the National Natural Science Project “Study on the Formation Mechanism and Strength of Shallow Loess Mudflows” undertaken by the Institute of Geomechanics of the China Geological Survey.Taking the Heifangtai area as a research area,the sliding mechanism of key landslides was studied.The groundwater environment in the study area was studied and a hydrogeological conceptual model of the area was established.The stability of loess slope under different conditions was analyzed and discussed,which provided theoretical guidance for the study of loess landslide warning in the study area.The following conclusions were obtained through research:(1)The number of pure loess landslides in the study area is dominant in the study area.Most of the landslides are seriously affected by groundwater,occur frequently and have a wide range of hazards,which may have reached 74.7% of the total landslides in the study area.Such landslides have emerged Strong,fast sliding speed and other characteristics.(2)The loess soil sample obtained in the study area has obvious strain softening effect.The increase of groundwater level will cause the sudden destruction of saturated soil mass in the infiltration zone.The groundwater level in the study area increased year by year due to irrigation.Due to the relatively poor permeability of clay soil,there was an infiltration zone inside the loess layer.Groundwater leaked from the junction of the loess and clay layers and eroded the slope angle,and the loess in the infiltration zone bore holes.As the pressure rises and the external disturbances are statically liquefied,the landslide slips.(3)The groundwater level rises with the irrigation time,and the center of the groundwater table also shifts from northwest to southeast.The thickness of the infiltration layer gradually thins from the center to the periphery,making the center of Taiwan and the southeast of Taiwan The head difference in the drainage area increases.As the groundwater table rises steadily,the stability of water-induced loess landslides in the study area will decrease in a geometric manner,and the frequency of landslides will increase significantly.(4)When the groundwater table is at a low level,the stability coefficient caused by it does not change much.This shows that under the high water level conditions,the elevation of groundwater level will play a controlling role in the occurrence of loess landslides.An observation device at the trailing edge of the landslide body can be used to monitor the surface elevation of the water in the loess aquifer in the study area.When the water reaches a distance of 30 m or more above the ground surface,and a groundwater drainage hole is found in the loess layer,it should be Make a landslide warning.