3-D fracture network dynamic simulation based on error analysis in rock mass of dam foundation

Abstract

Accurate 3-D fracture network model for rock mass in dam foundation is of vital importance for stability, grouting and seepage analysis of dam foundation. With the aim of reducing deviation between fracture network model and measured data, a 3-D fracture network dynamic modeling method based on error analysis was proposed. Firstly, errors of four fracture volume density estimation methods (proposed by ODA, KULATILAKE, MAULDON, and SONG) and that of four fracture size estimation methods (proposed by EINSTEIN, SONG and TONON) were respectively compared, and the optimal methods were determined. Additionally, error index representing the deviation between fracture network model and measured data was established with integrated use of fractal dimension and relative absolute error (RAE). On this basis, the downhill simplex method was used to build the dynamic modeling method, which takes the minimum of error index as objective function and dynamically adjusts the fracture density and size parameters to correct the error index. Finally, the 3-D fracture network model could be obtained which meets the requirements. The proposed method was applied for 3-D fractures simulation in Miao Wei hydropower project in China for feasibility verification and the error index reduced from 2.618 to 0.337.

Keywords

rock mass of dam foundation / 3-D fracture network dynamic simulation / fractal dimension / error analysis / relative absolute error (RAE) / downhill simplex method

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