The Strength Reduction Method Application In Analysis Of Stability Of Expansive Rock Slope

This paper conducts the research on expansive rock channels slope engineering which in Xinjiang.Systematic elaboration on the mineral composition of expansion rock, distinguishing index and gradingstandards, as well as the characteristics of engineering properties, aiming at the special engineeringproperties, calculation and selection for the expansive rock of shear strength index, study on different drydensity, water content influence on shear strength and residual strength of expansive rock remoldedsamples, and study on the influence of the shear strength of expansion rock remolded samples which indifferent cycles of wetting and drying times and repeated direct shear test times. In order to solve practicalproblems in engineering, through engineering examples, by using the finite element software (ABAQUS)on channel in different replacement depth, infiltration depth, using temperature control of strengthreduction finite element method in stability analysis, and using Duncan-Chang E-μ model in deformationanalysis. The main conclusions are as follows:(1)In the shear strength test of expansive rock, the shear strength of expansion rock which in the nativestate found effect of Shear specimen size, the shear strength of expansion rock was which in the native statefound effecting by Shear test specimen size, the shear strength index of small-sized bigger thanmedium-sized ones, direct shear data of medium-sized test more discrete than small-sized expansionrock,in saturated state, especially cohesion is almost zero. In the triaxial compression test, using the theoryof curve Duncan-Chang, E-μ model derivation in the initial stage (strain within5%) can fit the test curvewell, in a certain range of deformation, still can use this model to fit..(2)In same dry density, the strength parameters of the expansive rock remolded sample with theincrease of moisture content exist the best moisture content, the peak intensity and residual strength werealso having a best water content. but the peak intensity effected by moisture content change is obvious. insame water content, remolded samples with the dry density increases, the cohesion increases linearly, therelatively of the angle of internal friction and dry density change is little, The peak strength and residualstrength have a little effected by dry density, its strength increases are small.(3)The strength parameters of expansive rock remolded sample decreased with increasing times of thedry-wet cycling, but at certain times, strength index decline was not obvious, and finally tends to be stable.using the modified Liu Huaqiang strength attenuation formula can reflect the strength attenuation of soilvery well.(4)In saturation conditions, the residual strength of expansive rock remolded sample has a littledifference of numerical with the strength in full development fracture. can use the residual strengthassessment of fracture under saturated condition was fully developed after the saturation intensity.(5) In the analysis of slope stability using strength reduction finite element method, when the channelinfiltration depth is shallow (1m), safety coefficient does not vary with the thickness changing. When thechannel infiltration depth is deep (2m or3m), replacement thickness is greater, the greater safetycoefficient.(6) In deformation analysis of the canal slope, analysis of deformation for different parts of the slope,the slope under different conditions are the central deformation is the biggest, top of slope deformation isvery small, the slope bottom minimum deformation.when the infiltration depth, different replacementthickness, slope bottom deformation difference is small, the he midpoint of the slope deformationdifference is slightly larger, the top of slope deformation difference is slightly largest; replacementthickness is small, slope surface deformation is large, horizontal displacement at the top of slope have agreater displacement at the canal outside, the greater possibility of slope destruction.(7) In a variety of different depth of infiltration, replacing small main layer within the minor principalstress is positive (tensile stress), but near the top of the slope exist tensile stress and bigger than at thebottom, also have appeared crack may.