Causes Of Landslides And Their Treatment Measures For Engineering Projects In Longxi Loess Areas

About one third of geological disasters of China occurs in loess areas,and Gansu Province is one of the most extensive loess-covered areas.With the rapid development of infrastructure constructions,the mechanized construction is greatly increased and the engineering activities of human are also greatly unprecedented.However,lots of potential risks exist,and landslide disasters occur more fervently.The protection theories and control measures of slopes have become one of the key issues in present engineering constructions.In this study,the cause and impact factors of the landslide,located at the Xiejiao Village of Kangle County in the Loess Plateau were analyzed,and the stability of the landslide was evaluated;and then,the optimized control design of the landslide was proposed.And some preliminary conclusions were drawn as follows:1)The effects of impact factors,i.e.geological structure,landform,stratum lithology,underground water,climate,on the landslide were analyzed.And it was found that the landslide was mainly triggered by three key factors:(1)high and steep side slopes were formed by artificial excavation;(2)the soil engineering properties of the slope were relatively poor;(3)the rainfall infiltration increased the self-weight of the slope,and decreased the cohesion and internal friction angle.2)The the stabilities of landslides was quantitatively evaluated based on the Mohr strength theory of soils and the dynamics equilibrium principle of slopes.The stability of the landslide was checked by the transfer coefficient method.Through the qualitative evaluation and quantitative analysis of the loess landslide,it was found that the landslide was in a sub-stable state under natural or earthquake conditions,while it was in an instable state under rainstorm conditions.3)Based on the Geo-Studio(a finite element software),a two-dimensional strain landslide was simulated.The development process of the plastic zone was reproduced,and the most dangerous sliding surface was determined.At the same time,some variables of the landslide were analyzed,e.g.main stress,normal stress,pore water pressure and friction.A numerical simulation was performed for the landslide to determine the most dangerous potential sliding surface and stability factor of the slope.4)Based on the control principles of landslides in loess areas,combined the causes of the landslide and the stability analysis of the slope,two kinds schemes were preliminarily adopted,i.e.landslide front sheet-pile retaining wall and sloping surface,landslide front retaining wall and main sliding direction anti-slide pile.Considering the economic and environmental benefits,the anti-slide piles,along with strengthening the ground drainage,were adopted to control the landslide.