A Comparative Study Of The Strength Reduction Method And Its Improved Method Based On A Finite Element Difference Method

The study on the slope stability has always been hot issues in the field of engineering. With the rapid development of our country’s construction and the complexity of both topographic and geological, this issue has become particularly prominent. The study involves of geotechnical problems is complex, not to mention the Irregular shapes as well as vulnerable to interference from the outside world, which makes the slope stability study more complex. That is why although many engineers engaged in slope studies; the progress has been relatively slow. And with the constant improvement of the project to carry out the speed, the relevant theoretical research has lagged behind the engineering practice.Due to the powerful data processing ability a computer has, more and more scholars began to combine the slope stability theory with computer technology to simulating the slope body damage. Many numerical simulation programs are based on strength reduction to simulation. The traditional FEM based on the strength reduction technique defines that shear strength parameters of soil (cohesion c, friction tan φ) should use the same reduction coefficient. However, when the slope damage occurs, the soil above the landslide surface doesn’t play the same role with the soil below to resist the slope sliding. Therefore they should have their own reduction factors F1 and F2. In view of this, this paper uses FLAC3D program to analyze slope problems, and then put forward to the improved strength reduction method. Because this method is in its infancy, this improved strength reduction method is more suitable for the slide with potential landslide surface, judging from the calculation efficiency. Main process of this paper is as follows:(1) This paper first gives a brief introduction about the FLAC3D finite difference numerical computation software and the strength reduction method. Then selecting ideal slope model with the safety factor is greater than 1, as well as the model with safety factor less than 1, to research and analysis. For a slope model, i reduce the shear strength of the soil above the landslide surface and the soil below the landslide surface separately, then putting forward the improved strength reduction method through comparison and analysis.(2) This paper verifies the reliability of the improved strength reduction method based on the results of the traditional strength reduction method, by changing the values of cohesion and friction angle to analysis whether the improved strength reduction method is reliable to evaluation of slope stability. And the following conclusions are drawn:A. Cohesion and friction angle have a great impact on the stability of soil slope.B. Compared the results between the traditional strength reduction method and the improved strength reduction method, the maximum safety factor deviation is less than 5%, which means that the improved strength reduction method is fit for the slope analysis.C. To the slope with safety factor greater than 1, the traditional strength reduction method has a higher evaluation of its safety than the actual situation, while to the slope with safety factor less than 1, the traditional strength reduction method has a lower evaluation of its safety than the actual situation. The improved strength reduction method is more reasonable to analysis the slope than the traditional strength reduction method.(3) This paper analysis the YouSuoTun landslide with the improved strength reduction method. I select the most typical profile of the YouSuoTun landslide to analysis, the sliding surface turned to be exactly the same with the most dangerous sliding face given by the prior geological exploration data.(4) As a measure with the advantages of good anti-slide performance, quick construction, applicable to any terrain, anti-slide pile gets the favor. This paper uses double row anti slide piles to reinforce the typical profile of the YouSuoTun landslide. Through single factor analysis on some anti-slide pile indexes, the law that the space between two row; the location of the anti-slide pile influence the slope stability are achieved. Then the optimal solution is obtained.(5) Finally, this paper summarized, and puts forward some suggestions for scholars who will carry out the relevant research in the further.