Stability Analysis Of Graben Slope Of Suida Expressway In Heilongjiang Province

During the construction of Suida Expressway project in Heilongjiang Province,the phenomenon of mud gushing and water gushing occurred in the cutting slope of some excavated sections,which was greatly affected by seasonal conditions.In order to ensure the follow-up construction of Suida Expressway project,it is necessary to fully understand the internal mechanism of cutting slope instability in excavation section,and analyze and evaluate its stability correctly.First of all,this paper introduces the general situation of the project.The instability of the slope is investigated through field investigation,and the physical indexes and microscopic characteristics of the slope soil are determined through laboratory tests.The soil categories are identified and named as loess-like subsandy soil and black silty clay.Through direct shear tests and SEM scanning electron microscopy tests on soil under different freezing-thawing conditions,the strength trend and microstructure characteristics of soil under freezing-thawing conditions were clarified.In order to construct the numerical model,the typical section is selected and introduced according to the site survey of the excavated slope.Secondly,based on the hydro-thermal coupling theory,combined with meteorological data and field survey,a proportional saturation/unsaturated transient hydro-thermal coupling numerical calculation model was constructed considering various climatic conditions.After model verification,the distribution characteristics of water field,temperature field and freezing depth of slope before and after excavation of Suida Expressway cutting slope were analyzed,which revealed the variation of water and heat during slope instability.Then,according to the stability analysis theory,the slope stability analysis model was constructed by combining the research results of slope soil strength and the research results of hydrothermal coupling numerical model,and the development trend of slope safety factor and potential slip surface location in Suida Expressway under different conditions were analyzed.The results show that K26-AA ’slope and K26-BB’ slope are in a less stable state at the initial stage of excavation,and K27 slope is in a basically stable state.After that,with the outflow of water in the slope,the stability is enhanced.At the beginning of excavation,the slope of K32 was in a stable state,and under the influence of rainfall,the stable state decreased and then rose steadily.Finally,the index system of slope stability evaluation for cutting in Suida Expressway is constructed to evaluate the stability of cutting slope in field engineering situation,and the results of stability analysis are compared.The results show that the stable state is basically the same at the initial stage of excavation,which proves the feasibility of the constructed model,but the stable state is low under some conditions.In this paper,the stability of cut slope is considered as a whole according to the two results.According to the overall research results,the protective measures of deformation monitoring + engineering drainage + engineering support + ecological slope protection are proposed and deployed.