دانلود مقاله probabilistic evaluation of underseepage of dam rock foundation considering spatial correlation in permeability
سال انتشار: ۱۳۸۴
محل انتشار: سمپوزیوم برآورد عدم قطعیت در مهندسی سد
تعداد صفحات: ۱۱
H. SATOH – Researcher, Dam Structures Research Team, IAA-PWRI, Japan
Y. YAMAGUCHI – Leader, Dam Structures Research Team, IAA-PWRI, Japan
Grouting is conducted to control underseepage of a dam rock foundation. In order to perform the grouting works efficiently, it is important to precisely estimate the spatial distribution of permeability considering the spatial correlation. However, it is difficult to estimate the permeability distribution of a dam rock foundation because it is underground work and because the permeability of the foundation varies spatially. Therefore, it is necessary to quantitatively estimate the uncertainties of the permeability distribution and their influences on the evaluation of underseepage in the dam rock foundation. To evaluate the influences of the spatial correlation of the permeability and the uncertainty of the estimation, we perform the Monte Carlo simulation using two-dimensional seepage analysis. In the Monte Carlo simulation, the spatial distributions of permeability are generated based on random numbers using the geostatistical method. Because we can consider the spatial correlation and the uncertainty of the physical properties such as permeability by using the geostatistical method, this method is now being used in many fields of engineering. In addition, the main flow path is evaluated from the results of the Monte Carlo simulation using the percolation theory. Percolation theory is commonly used to consider the connections of various phenomena, and we treat the main flow path in the seepage analysis results as the connection of the high-velocity elements. Because the velocity distributions are greatly influenced by the various spatial distributions of permeability generated by the geostatistical method, we evaluate the main flow path probabilistically, and we consider the influences of the spatial distribution of permeability or the influences of the grouting specification, such as depth or the target value of imperviousness. We find that the spatial correlation, especially the lateral correlation, of the permeability is important for the formation of the main flow path.