Influence Of Dry-wet Cycles On The Strength And Stability Of Loess Embankment Slope

Taking the slope of loess embankment Q₃ between Sanmenxia and Xichuan Expressway?Lingbao-Lushi-Xiping section?as the research object in this paper,the paper studies the load ratio?CBR?and shear strength of loess embankment slope under the action of dry-wet cycle.The cohesive force c,internal friction angle?,etc.Most of the shear strength parameters are mainly tests,the test conditions are different,the parameters obtained are very different,so it is necessary to take effective parameters according to the actual working conditionsIn this paper,through CBR test and triaxial shear test,the variation law of subgrade bearing capacity and shear strength parameters,such as cohesive force c and internal friction angle?,are obtained under different dry-wet cycle conditions.The mechanical mechanism of loess strength attenuation under different conditions and the deformation and failure of loess embankment slope are revealed,which provides a certain reference for practical engineering.Finally,based on the Mohr-Coulomb deformation and failure theory of soil mass,the slope deformation and stability analysis is carried out by using PLAXIS software,and somemeaningfulresearch results areobtained as follows:?1?In CBR experiment,the CBR value decreases with the increase of cycle times.When the cycle times are the same,the penetration increases with the increase of unit pressure,and the more cycles,the more serious the soil failure.After repeated cycles,the strength deterioration effect accumulates,the strength decreases obviously,the original integrity of the structure is destroyed,and thestrengthofthe soil decreases.?2?In triaxial shear tests,the failure modes of compacted loess are mainly weakly softening,ideal elastic-plastic and weak hardening.With the increase of water content and compaction degree,the stress-strain curve of the specimen changes from weak softening type to ideal elastoplastic and hardening type,and increases with the increase of dry-wet cycle times.The stress-strain curve of the specimen has an ideal elastic-plastic transition to a weak hardening type.The relationship between cohesive force c and water content w is linear,and the relation with compaction is exponential,which decreases with the increase of dry-wet cycle times,and the internal friction angle increases with the increase of moisture content and the number of dry-wet cycles.With the increase of compaction degree,theeffectofwatercontent onshearstrength isthe most important.?3?With the increase of water content,the displacement and deformation gradually increase,the stability coefficient of embankment slope decreases gradually,the stability decreases,and the ability to resist deformation weakens,which is obviously affected by water content.When the water content is 9.7%,The plastic deformation of the slope body begins with the slope foot,the shallow layer of the slope body is first affected,and the local deformation is obvious.When the water content is 18.7%,the displacement deformation gradually concentrates to the bottom slope foot and gradually becomes larger,and finally produces a certain amount of displacement deformation at the slopefoot.Thedisplacementdeformation ofthe wholeslopeis frompart to whole.?4?In the stability analysis,with the increase of dry-wet cycle times,the deformation displacement of embankment slope increases,the overall stability is destroyed,the strength of soil decreases,and the ability of resisting deformation decreases.The range of displacement and deformation of embankment slope gradually diffuses from shallow layer to deep layer,indicating that theeffectofdry-wet circulation onslopebody isfromshallowtodeep,fromlocal towhole.?5?After the third dry-wet cycle of embankment slope,the foot of the third floor embankment has obvious displacement and deformation,and the displacement of the foot of the slope increases obviously after the fifth dry-wet cycle,and the influence range is enlarged,which indicates that after several cycles,the possibility of failure of the foot of the slope is greater.According to the displacement cloud map of slope body under different conditions,the influence of watercontenton slopebodyis greaterthanthaton slopebody bydry-wetcycle.