Study On The Value Of Rock And Soil Load On Retaining Structure Of Polygonal Sliding Surface Slope

Whether the supporting and retaining structures are reasonable and effective affects the safety and stability of the slope and surrounding projects directly,and the rock and soil load on retaining structure is the most concerned problem during designing the support structure such as the retaining wall or anti-slide pile.For polyline sliding slopes such as soil-rock mixed slopes,China usually adopts the residual sliding force calculated by the transfer coefficient method as the rock and soil load on retaining structure.However,the sliding surface and geotechnical calculation parameters are limited and uncertain.Based on the spatial interpolation method,ultimate balance theory and reliability theory,the determination of the sliding surface and the calculation method of the rock and soil load on retaining structure are studied.The main work and conclusions are as follows:The following three aspects of the polygonal sliding surface are mainly studied and solutions are proposed to reduce the calculation deviation caused by the determination of the polygonal sliding surface:(1)When the single sliding surface is too long,the calculation based on the entire block will underestimate the rock and soil load on retaining structure,and the too thin partition will increase the amount of calculation.The principle of size division is proposed.(2)When the inclination angle difference between two adjacent sliding surfaces is too large,the calculation result obtained is underestimated.It can be processed by applying the chamfering method or rounding angle to the two sliding surfaces.(3)When the bedrock surface undulate largely or the borehole spacing is large,the polyline sliding surface obtained by adjoining two adjacent holes in a straight line is not consistent with the actual sliding surface.Support vector machine algorithm is used to predict the elevation of sliding surface between boreholes in order to approximate the actual polyline-shaped sliding surface shape by adding polylines to calculate the load on retaining structure more accurately.The transfer coefficient method belongs to the single safety coefficient method,which cannot reflect the safety reserve of the slope,so the reliability analysis design method and design method of limit state of partial coefficient are introduced.For the calculation method of the rock and soil load on retaining structure,the following contents are mainly studied:(4)The two existing calculation methods and their characteristics are summarized.One is based on the remaining sliding force,the other is based on the slope stability coefficient after retaining.And the load on retaining structure obtained by the two methods is compared according to the example,and find that the method based on the slope stability is safer.(5)Using random field theory to consider the spatial variability of shear strength parameters,its application in calculating the load of supporting structure is put forward,and sensitivity analysis was carried out form the aspects of the vertical and horizontal autocorrelation distance,shear strength parameters' variation level and the safety factor of stability.(6)The basic principle of the limit state design method of partial coefficients is systematically introduced.The general separation method is used to calculate the partial coefficients of the parameters,and on this basis,the calculation formula for the partial coefficient method of the rock and soil load on retaining structure are derived.(7)The slope reliability index is deviated from the target reliability index,and for a single slip slope,the deviation is within 6%.For more complex slopes,such as polyline slopes,the deviation is larger.