كليدواژه :
Dam foundation , Main flow path , Monte-carlo simulation , Seepage analysis , Geostatistics
چكيده لاتين :
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.
