Slope Stability Analysis And Simulation Based On Strain Information

In this paper, the abruptness of the displacement strain and soil displacement occurred at a certain node in the slope are taken as instability criterion for evaluating the stability of slopes. Combined numerical simulation with model testing method, the stability study of slope is conducted in the condition of applying uniform surface load, changing soil parameters and excavating the slope. The strain distributing disciplinarian and the relationship between safety factor and the maximum horizontal linear strain are obtained in these conditions. Main work of this paper can be summarized as follow:(1) The method of slope stability analysis and the criterion for evaluating slope stability have been explained, and three kinds of strain monitoring techniques, including electric resistance strain gauge, FBG and BOTDR, have been analyzed and compared.(2) Combined strength reduction method with limit equilibrium method, the stability of slope based on numerical simulation method is conducted under the condition of applying uniform surface load. The results show that the sliding surface determined by the line connecting the points where shear strain increment is maximum and the sliding surface determined by the line connecting the points where horizontal (vertical) linear strain is biggest are all consistent with the sliding surface determined by the limit equilibrium method. This indicates that taking the linear strain mutation on sliding surface as a criterion for slope instability and searching for the location of sliding surface is reasonable and feasible. Based on the definition of characteristic horizontal linear strain, the relationship between safety factor and the characteristic horizontal linear strain are obtained. This result can provide a theoretical guidance for slope stability assessment and perform early warning of landslides.(3) The stability study of slope based on numerical simulation method is conducted under the condition of changing soil parameters. The results show that when the values of cohesion and internal friction angle are large, the strain concentration phenomena will occur in the middle of the slope. With the decrease of cohesion or internal friction angle, strain concentration phenomena will occur in multiple areas within the slope, which suggests that many potential sliding surfaces exist in the slope. Upon slope failure, the strain concentration area will decrease and slippage of slope mass happened in one of the strain concentration areas. The results show that upon slope failure, the sliding surface determined by the line connecting the points where horizontal linear strain is biggest are consistent with the sliding surface determined by the limit equilibrium method.(4) The stability study of slope based on numerical simulation method is conducted under the condition of excavation by steps. The results show that with the excavation going on, the potential sliding surface will change. However the strain concentration area will always emerge at the slope toe. The decrease and slippage of slope occur in one of the strain concentration areas. The results show that upon slope failure, the sliding surface determined by the line connecting the points where horizontal linear strain is biggest are consistent with the sliding surface determined by the limit equilibrium method. So in the monitoring of the slope stability based on strain information, the priority should be given to the monitoring of linear strain in the middle part and the toe of the slope.(5) The stability study of slope based on model test method is taken in the condition of Layered Excavation. In the process of slope excavation, the change of strain in the slope presented ladder lanes. The value of strain in the middle part of the slope is significantly bigger than the value of strain in the rest parts of the slope and strain concentration phenomena occur in the middle of the slope. Establish the relationship between safety factor and the characteristic horizontal linear strain and compare the result with the conclusion of the stability study of slope based on Numerical Simulation method, it suggest that This indicates that taking strain information as a criterion for slope instability is reasonable and feasible.