Study On Soil Slope Reliability Based On Random Field Theory

Slope stability analysis is one of the classical topics in geotechnical engineering, meanwhile, it is a critical point in safety evaluation of earth dams. The traditional factor of safety method in slope project fails to fully consider the uncertainties in different working conditions of the earth, which have a noticeable impact on the analysis results and cannot be ignored. In view of the deficiency of traditional factor of safety method in slope project, it is of important significance to introduce random fields theory and reliability theory into slope stability analysis.This thesis focused on the the application researches on slope stability of reliability analysis method and the random field of mechanical parameters for soil, then summarized the sources of uncertainty and its effect on the reliability of calculation. A C++ program is developed to apply this method with an earth dam in Henan. Meanwhile, the effects of the variability and association of c andφon slope stability are analyzed. By means of case analysis, the following conclusions can be obtained:1. When it is in inverse relationship between c andφ, the reliability index of slope will increase with increasing of correlation coefficient's absolute value; when it is in positive correlation between c andφ, the reliability index will decrease with increasing of correlation coefficient; it is always in negative correlation beteen c andφ, so it is good for the slope stability. The result is conservative to predict slope safety without considering the correlation because the soil parameters is always negatively correlated.2. Changeability of material parameters adversely affect the slope safety. In the case of same safety factor, the reliability index will decrease with increasing of the coefficient of variation,while the the failure probability will increase.3. In the case of same safety factor, the reliability index is particularly sensitive to friction factor tanφ.On the basis of random field theory, the influences of correlation and variability between c andφon slope reliability are analyzed, a method is proposed to simulate the characteristic section with one-dimensional or two-dimensional random field, it is adopted to modify the parameters, the result shows that the reliability index increased greatly considering parameters'spatial variability.The reliability method based on random field theory can directly calculates the failure probability. It is proved more intuitive and practicable in slope project compared with the traditional factor of safety method. It is of great signifiance to determine the reasonable correlation distance and correlation function in reliability analysis, but in this field theory aspects is not so perfected that it needs further research.