Research On 3D Slope Strength Reduction Method Based On Inclined Deformation

Slope instability is a common geological disaster in the field of transportation and civil engineering in my country,which brings potential safety hazards to people's lives and property and social and economic development.Therefore,it is very important to carry out research on slope stability.The slope stability analysis includes two key issues:the critical state of the slope and the determination of the position of the critical slip surface of the slope.Aiming at two key issues in slope stability analysis,this paper takes three-dimensional rock slope as the research object,adopts Mohr-Coulomb criterion of equivalent strength parameters instead of the Hoek-Brown criterion to carry out strength reduction calculation in FLAC 3D software,and carries out three-dimensional slope stability research work based on incline deformation.First,establish three-dimensional slope numerical calculation models with different slope heights,slope angles,and aspect ratios,continuously adjust the strength reduction coefficients to simulate the progressive failure process of the slopes,and study the variation law of the spatial inclination angle of slope top monitoring points with different calculation lengths of inclination deformation.And the slope safety factors are calculated based on the relationships between the inclination deformation of the monitoring points and the strength reduction coefficients,and then a method for judging the critical state of the slope based on the inclination deformation is proposed.Then,a three-dimensional numerical calculation model of the slope is established,and the strength reduction method is used to calculate the slope in a critical failure state,study the characteristics of the spatial inclination deformation of the points on the critical slip surface when the slope is in the critical failure state,search for the position of the critical slip surface of the slope by the spatial inclination angle,and then propose a determination based on the inclination deformation method for critical slip surface of slope.The main conclusions of this paper are as follows:(1)In the process of slope progressive failure to instability,the spatial inclination deformation of the slope top monitoring points have a sudden change with the increase of the strength reduction coefficients.(2)The angle-reduction coefficient relationships of the monitoring points under different calculated lengths of inclined deformation shows that:the sensitivity of the angle change of the monitoring points improves with the calculated length of the tilt deformation increases.(3)The hyperbolic equation has a good fitting effect on the angle-reduction coefficient relationship.The equation can be used to fit and calculate the slope safety factor,and when the slope deformation calculation lengths increases,the value of the correlation coefficient R~2 will increase to a certain extent,and the fitting effect of the angle-reduction coefficient relationship of the monitoring points on the slope top monitoring line will be improved.(4)The relative errors of the slope safety factors calculated by hyperbolic equation fitting for the angle-reduction coefficient and FLAC 3D software are within5%,which are close to the slope safety factors calculated by the feature points displacement mutation criterion,which indicating that the method of determining the critical state of the slope based on the inclination deformation is feasible.(5)The critical slip surface of the slope can be characterized by the position of the maximum spatial inclination angle.A series of spatial points that characterize the critical slip surface are found by arranging search paths and discrete points,and the three-dimensional critical slip surface of the slope can be obtained by LOWESS method to smooth many scattered points.(6)Choosing different calculation lengths of inclination deformation to calculate the spatial inclination angle generated by the discrete points on the search path has little effect on the position and shape of the critical sliding surface of the three-dimensional slope.As the distance between discrete points decreases,the shape of the critical slip surface is close to the real three-dimensional slope critical slip surface under fully constrained boundary conditions.