Three-dimensional geometrical simulation of rock mass discontinuities network in the access tunnel of Rudbar Lorestan dam & hydropower plant

In this paper, Given the high importance of joint persistence characteristics on the mechanical behavior of the rock mass, geometric-stochastic joint network model, based on Veneziano method, has been developed by considering the statistical characteristics of joint size. Using surveyed data in the access tunnel of Rudbar Lorestan dam & hydropower plant and estimation of the best probability distribution function on geometric characteristics of existing joint sets in the study area, three-dimensional (3-D) geometric model of joint network has been presented. Nowadays, modeling is increasingly put forward as a method of determination of rock mass strength characteristics. An accurate description of the rock mass structure does provide a better starting point for modeling of rock mass. Besides, there will always be some random variation in the geometric properties of joints by virtue of rock mass heterogeneous nature. Therefore, it is necessary to describe the ordered properties stochastically and to use in rock mass modeling. 3-D stochastic joint network modeling technique represents the most optimal choice for simulating the probability nature of joint geometric properties. Methodology and Approaches: Using field measurements and statistical analysis, stochastic parameters of discontinuities are detemined. In this paper, collected data is obtained using a linear surveying. Data processing including matching different probability distribution function on geometric properties of surveyed joint sets has been performed using Dips and EasyFit software packages. In order to calculate volumetric joint density, joints, which have been visible to the naked eye in the field, have been counted within an area of 1 m2 using a square frame (1×1 m) with grid lines at 10 cm intervals. Using the areal joint density and existing equations, the volumetric joint density has been calculated for each joint set, separately. Thus, to prepare the geometric-stochastic model, the required inputs,mentioned above, have been used. The generated joints by the developed model, are coincided on the ordered probability distribution function of joint persistence. Results and In this paper, a 3-D geometrical- stochastic discontinuities network model for the access tunnel of Rudbar Lorestan dam has been presented. In order to model implementation, a computer code written in C++, named DFN-FRAC3D, has been developed to represent the joint network in different directions and to generate digital outputs. The results of this paper can be a useful input for numerical stability analysis and hydraulic behavior studies of rock mass.