Research On Deformation And Stability Control Mechanism Of Loess Slope Supported By Frame Prestressed Anchors Under Earthquake Action

The landform of Northwest China is mainly mountainous of loess,and it is one of the main areas of strong earthquake activity,due to the advantages of effectively limiting the lateral displacement of the slope and improving the stability of th e slope,the frame prestressed anchors has been widely used in the engineering practice of slope in the loess area of Northwest China,and has been widely concerned by a large number of scholars.At present,the research on the reinforcement mechanism of f rame prestressed anchors mainly focuses on the anchoring mechanism of anchors,however,there are few research on deformation and stability control mechanism of loess slope supported by frame prestressed anchors under earthquake from the synergy of anchors-frame-soil.This paper is based on the current research status,theoretical and numerical simulation are used to research on deformation and stability control mechanism of loess slope supported by frame prestressed anchors under earthquake,the main research contents are as follows:(1)Optimize some coefficients in the calculation formula of dynamic earth pressure on the existing supporting structure,determined that the dynamic earth pressure on the supporting structure presents a cubic curve distribution pattern with the slope height,then analyze the force of the supporting structure and determine deformation mechanism of loess slope supported by frame prestressed anchors under earthquake,on this basis,a simplified dynamic model of the supporting structure is established,and then the slope horizontal dynamic displacement is solved,the relationship between the horizontal dynamic displacement of the slope and the slope height is established.The comparison and verification of theoretical calculation and finite element simulation ensure the rationality and feasibility of algorithm in this paper,then the horizontal dynamic displacement of the supported slope and the unsupported slope is compared,the results show that the frame prestressed anchors has good seismic performance.(2)Use horizontal and vertical slice method to establish dynamic stability of slope calculation model,the range of the anchors anchoring area is solved,take the horizontal soil strip as the horizontal soil layer within the range of the anchors anchoring area,the vertical soil strip is taken as the vertical soil layer corresponding to the sliding surface of the horizontal soil strip,then the force balance and moment balance of the above two soil strips are combined through the sliding surface side pressure and the sliding force,the analytical solutions of all unknown inter-strip forces on the soil strips is solved,and the calculation formula of supported slope dynamic stability is solved.Apply the above calculation method of inter-strip force and stability calculation method to unsupported slope,then the calculation formula of the dynamic stability coefficient under earthquake action is solved.Use the algorithm in this paper and the finite element method to calculate the actual engineering examples,on the basis of ensuring the rationality and feasibility of the algorithm in this paper,the stability control mechanism of loess slope supported by frame prestressed anchors under earthquake action is analyzed.The results show that the main function of the frame prestressed anchors under earthquake is to increase the normal force on the surface of the soil strip and reduce the tangential force,thereby,the integrity of the slope under the action of earthquake is improved,and then the dynamic stability coefficient of the slope under the action of earthquake is improved.(3)Taking a slope engineering in Lanzhou as the background,with the help of Geo Studio finite element software,the dynamic finite element model and the finite element model of the dynamic stability of the loess slope supported by frame prestressed anchors are established,the influence of beams spacing,columns spacing,anchors inclination angle,groundwater level,anchors prestress and vertical earthquake on deformation and stability control mechanism of loess slope supported by frame prestressed anchors under earthquake are analyzed.