Study On Stability Analysis And Treatment Of Soft Hard Rock High Slope Excavation

Soft interlayer is a major safety hazard in slope engineering.Soft and hard interbeds have more complex geological structure and mechanical characteristics than single weak interlayer,which makes it easy to instability in excavation and treatment.Limited by indoor test site,the research on soft hard interbedded rock high slope mainly focuses on the failure mechanism and structural strength analysis based on model test,and the lack of Application Research on slope excavation and treatment in real scale,so the research results are difficult to solve the problems encountered in actual engineering.Based on the engineering geological investigation,the paper mainly uses numerical test and numerical simulation method to study the failure process of soft hard interbedded rock mass under triaxial compression and unloading.The change of stress and strain,displacement and plastic zone of the slope before and after excavation is analyzed.The excavation stability of the actual engineering of soft hard interbedded rock slope under different working conditions is calculated,The optimal treatment scheme is determined by optimization comparison and selection,and the improvement effect after slope treatment is analyzed.The main research results are as follows:(1)In the process of triaxial compression test of soft and hard interbedded rock,the higher the confining pressure,the more concentrated the plastic damage area in the failure of the model is 45 ° The shear crack line of;The larger the confining pressure and thickness ratio,the greater the peak value of partial stress;The larger the inclination of rock,the smaller the peak value of the partial stress.(2)During the numerical test of soft and hard interbedded rock mass unloading,the model has obvious lateral expansion,and the damage area gradually concentrates,and finally forms the through plastic zone in a certain part and breaks down.The main shear fracture is ductile under low confining pressure;Shear failure is the main factor in high confining pressure.The higher the initial confining pressure and thickness ratio,the higher the peak value of partial stress;The higher the inclination of rock,the lower the peak value of the partial stress.(3)During the process of excavation and unloading,soft and hard interbedding has a great influence on the maximum principal stress and shear stress distribution of the slope.The strain of slope mainly occurs in soft rock and mainly concentrates in the disturbed area of excavation.The main displacement of slope is the horizontal displacement of the slope toe and the vertical settlement of the top of the slope.The plastic zone and strain are distributed from the foot of soft rock layer closest to the new excavation surface along a certain arc to the top of the slope.The slope stability is obviously affected by the construction conditions,and the stability coefficient of the slope under the heavy rain condition after each excavation is about 18.54% lower than that of the natural condition.(4)The optimized treatment scheme can improve the distribution of stress,strain,displacement and plastic zone of slope.The stability coefficient of the slope after treatment was increased from 0.887 to 1.456,and the effect of the treatment was significant.