Slope Stability Analsis And Its Protection Research Based On Strength Reduction Methou

In this paper, aiming for the construction of subgrade widening without suspending road service, finite element analysis was performed on this special engineering status using strength reduction method in subgrade slope stability analysis.In order to know well that how cross section geometric morphology and soil quality mechanical strength factors perform influence on the stability of the construction of subgrade widening without suspending road service, laboratory experiments were done on representative soil sample from site to measure their physical and mechanical properties. A subgrade slope stability model using strength reduction method was build according to the laboratory experiment results and impact analysis was made on cross section geometric morphology, material mechanics index and calculated parameters. Two methods for protecting the slope were proposed according to the model calculating, in order to make the construction process more precise in theory.The results show:1. The subgrade slope stability model using strength reduction method performs well in imitating this special construction method. The displacement of one point in the slope and the mutation point in relation curve of reduction factor was treated as discriminating standard in analysis process.2. In this model, subgrade filling height should not be over high, and the gradient of the slope should be over1:1.5. The safety factor becomes larger as the number of the step in excavation process goes larger, which means that multilevel excavation makes construction safer. C,φ and dilatancy angle of subgrade soil can affect the slope stability factor significantly, but C and dilatancy angle of soil base basically perform no affect and φ perform less affect than subgrade soil does. The rebound modulus of both subgrade soil and soil base perform little affect on the slope stability factor. The load of roller is a significant factor. When the load is over4500KN, the slope stability factor drops rapidly and the slope fails.3. Using geotechnical grille and disposal soil transferring are two economic and practical methods for protecting the slopes. The slope safety factor doubles, illustrating that geotechnical grille can offer great support, when geotechnical grille is set. And the slope safety factor increase38.2%when disposal soil transferring method is used, illustrating that disposal soil transferring method performs well in improving the stability of the slope.