Deformation Calculation And Stability Analysis On High Reinforced Slope

In the western mountains, cutting hills to backfill ditchs not only meets the needs of disaster prevention and mitigation, but also contributes to ease the shortage of land. With Lueyang comprehensive treatment project in the Phoenix Mountains, FEM calculation of stress and strain field and stability analysis to Tuqiaogou and Luojiagou Embankment are done in the paper. The following is the main contents in the paper:(1) The stability of the concrete retaining wall located in the lower embankmen is analysed. The influence of the downstream face slope, the upstream face angle, friction angle of soil behind the wall and seismic intensity is studied. The calculation results show that: reducing the downstream slope or increasing the upstream face angle and internal friction angle can increase the stability of the concrete retaining wall; When the downstream face slope is 1:0.8, the the concrete retaining wall of Tuqiaogou Embankmen meets the normal use and seismic requirements; to the concrete retaining wall of Luojiagou Embankmen, the downstream face slope of 1:0.8 can meet the normal use and seismic requirements.(2) Using the FEM softward ABAQUS, stress and strain fields in Tuqiaogou Embankment and Luojiagou Embankment are calculated and the influence of soil deformation modulus, Poisson's ratio and deformation modulus of geogrid is studied. The results show that: increasing deformation modulus of soil, horizontal displacement and vertical settlement are reduced at the same time; increasing Poisson's ratio, the horizontal displacement increases, but the vertical settlement decreases; increasing deformation modulus of geogrid, the horizontal displacement decreases, but the vertical settlement remains unchanged.(3)Using the software STAB developed by Chen Zuyu Academician, the reinforced slope stability under normal use and seismic load conditions is calculated. The calculation results of Swedish circle method and simplified Bishop method show that: the reinforced slopes of Tuqiaogou Embankment and Luojiagou Embankment meet the normal use and seismic requirements. (4) Using ABAQUS software, the reinforced slope stability is analysed by FEM strength reduction, and three slope failure criteria are studied. When the equivalent plastic strain zone with a given value develops from the toe and the top, the displacement occurrs mutation or calculation fails to converge, we think the slope becomes instable. The calculation results show that the safety factor of slopes under different criteria is different. The safety fator is not reliable if single criterion is used to judge whether the slope is safe or not was used. So the three slope failure criteria should be all considered. If the tensile force of geogrid is beyond tensile strength, the slope may slide. So the tensile forces of geogrid should be considered as a secondary criterion of slope failure and the criterion for reinforcement design rationality. Studies show that: the stress of the geogrid in toe of the slope often firstly reaches its tensile strength, and local instability in reinforced slope may be control factors.(5)Based on the vector characteristics of slope sliding, safety factor formula of vector sum method is constructed. It assumes that the geigrid has the same safety factor with soil, and vector sum method in natural slope is introduced to the reinforced slope safety analysis. The results show that whether it is natrual slope or reinfored, the results of vector sum method were similar with the limit equilibrium method. It overcomes shortcomings of FEM strength reduction-the safety fator is subjected to failure cateria and stress field is unreal.