Research On Slope Stability Considering The Behavior Of Loess Rheology

Geologic hazards such as landslides and debris flows can cause detrimental effects on structures and result in loss of human life. In recent years, the frequencies of geologic hazards are rising. One of the most important behaviors of geologic materials is rheology and lots of landslides indicate rheologic characteristic phenomena before their failures. It is important that rheologic behavior of soil should be considered for analysis slope stabilities.In north-west of china, most regions are covered by loesses. With the developing campaign in that area, large scale constructions such as railway, expressway and urban base facilities are in building. As a result, loess slope failures are increasing with more loess slopes produced by constructions. In this paper, loess rheologic property is taken to study the slope stability and main works are below:1. Hydrological and Engineering Geology have been investigated about two loess landslides which located in the sections of shannxi tongchuan-huangling expressway between 151,890 meters to 152,080 meters and 157,130 meters to 157,380 meters.2. Creep and stress relaxation couple laboratory tests have been carried out which soil got from sites that two expressway landslide projects above. Two types of couple rheology tests were carried out: direct shear creep and stress couple tests; Triaxial consolidation-undarianed creep and stress couple tests, which were used to detect the changing of the pore water pressure in testing. In order to prove the common rheologic properties of loess, other direct shear couple rheology tests were carried which soil obtained from xi'an university architecture & technology official building excavation project, different pore water content soil specimens also carried in this test. Through the laboratory rheology tests above, some loess rheologic principles are included. Long term strength of loesses contrast with short term strength has obvious decrease.3. Based on the stress-strain-time relation principles of loess couple rheology tests, constitutivemodels are proposed: the first method is experience model that using double line stress-time logarithmic curve to simulate testing date, the other is five elements Kervin couple rheology model to mimic testing date. The results show that two constitutive models provide highly satisfactory correlations for the behaviors of loess creep and stress relaxation couple rheology proceeds.In the end of this paper, analysised two slope stabilities with loess rheologic theory. The results show that loess rheologic characteristics have magnitude effects on slope stabilities. So, it is necessary to consider loess rheology when calculation the slope stability. Although this paper discussing loess slope stability, it can be used for reference in other type soils slope stability analysis.