Study On Slope Stability Of Deep Foundation Excavation Based On The Gray System Theory

In recent years, the rapid development of high-rise buildings and the full utilization of underground space accelerate the development of deep foundation, this will bring about a large scale of deep foundation excavation. However, due to the complex stratum conformation, the high uncertainty in soil properties and the defect in design and construction management, the instability and the collapse of deep foundation excavation slope are common forms of accidents, and cause huge economic losses and adverse social impact. There is a lot of objective uncertainty in traditional slope stability analysis of deep foundation excavation; giving full consideration to the uncertainty caused by a variety of factors is the development trend.The principle and applicability of some limit balance methods, which are commonly used and simplified in the slope stability analysis, are introduced. And the flaw of several uncertainty analysis methods is pointed out.The application of gray system theory in the deep foundation excavation slope stability has just begun. A GM (1,1) model was set up for the horizontal displacement data of the supporting structure of deep foundation excavation through the choice of gray prediction model, and the time—horizontal displacement relationship is fitted and predicted. The results show that the precision of model itself is very high, the error in fitting and prediction is fairly small; and the error of prediction model set up by 5 data is 0.01, which shows that is a good result.The relational analysis method of the gray system theory is adopted in analyzing the effects of the excavation slope stability for the first time, the role of factors is classified in order to define the extent of the impact and provide guidance for construction design. By using gray correlation analysis in deep foundation excavation supported by soil nail wall,the main reason and the corresponding control measures for instability of the slope are identified. It shows that gray system theory can be effectively and practically adopted in the slope stability analysis of deep foundation excavation and that has a good prospect. The security state of slope can be controlled effectively by predicting deformation using gray model. Practical effect in controlling slope instability can be obtained via gray correlation analysis.