The development of a method to generate constitutive properties of the jointed rock mass, requiring limited number of experiments, and the related numerical model of the jointed rock mass for introduction in modern high-techgeomechanically oriented computer codes should partly fill the existing gap between experimental and numerical techniques in rock engineering. This goal can be reached by combining accumulated experience and factual data with the capabilities of recent computer methods. As the first step in the creation of a comprehensive numerical model for jointed and layered rock, a series ofFEM numerical experiments was conducted in 2D and 3D for jointed rock blocks using Mohr-Coulomb, multilaminate and Hoek-Brown models. Compression strength and deformation parameters of blocks were evaluated for different joint spacing, joint thickness and joint inclination angles. The results fit well into the multitude of independent experimental, analytical and numerical data. Practical implementation is shown.
1. INTRODUCTION
Tunneling in jointed rock masses requires good understanding of rock-structure interaction processes. Most practical examples need three dimensional representations of rock mass and structural elements for realistic description of such processes. The joint system determines the behavior of rock masses in many cases more than any other factor [1]. Strength and deformation behavior of rock masses are governed by joint distribution, orientation and properties. Both continuous and discontinuous approaches in numerical modeling are recently in use for prognoses of the structure behavior in jointed rock masses. Explicit numerical modeling of jointed rocks is a tedious task, the main drawback being difficulty if not impossibility to represent with sufficient detail and reliability the rock mass structure and joint properties. The appealing explicit clarity of the discontinuous approach is thus restricted by usual uncertainty of real joint distribution and properties along with considerable computational effort of the 3D distinct element modeling.
Continuous approach requires implementation of implicit models with somehow averaged deformation and strength parameters for jointed rock masses. The development of constitutive models for jointed rock has been the subject of many investigations in experimental rock mechanics and related software engineering. Many different models were developed and published recently, only a few are used in practice, the reason being the high cost of input parameters evaluation and the dependency of the models on particular features of rock masses. The evaluation of effective properties of rock joints is the least developed area in modeling rock masses. The problem here is the difficulty of representing the real irregular roughness of the joint in a regular model and, especially, of evaluating the sizes and angles of joint protuberances and of introducing these factors into the numerical model.
