Statistics for Spatial Data.

A review of techniques, advances and outstanding issues in numerical modelling for rock mechanics and rock engineering

The goal of this review paper is to provide a summary of selected discrete element and hybrid finite–discrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fracturing processes in rocks and rock masses. The fundamental principles of each computer code are illustrated with particular emphasis on the approach specifically adopted to simulate fracture nucleation and propagation and to account for the presence of rock mass discontinuities. This description is accompanied by a brief review of application studies focusing on laboratory-scale models of rock failure processes and on the simulation of damage development around underground excavations.

https://cyberleninka.org/article/n/14358.pdf

A review of discrete modeling techniques for fracturing processes in discontinuous rock masses

The effect of scale on the shear behaviour of joints is studied by performing direct shear tests on different sized replicas cast from various natural joint surfaces. The result show significant scale effects on both the shear strength and deformation characteristics. Scale effects are more pronounced in the case of rough, undulating joint types, whereas they are virtually absent for planar joints. The key factor is the involvement of different asperity sizes in controlling the peak behaviour of different lengths of joints. It is shown that as a results both the joint roughness coefficient (JRC) and the joint compression strength (JCS) reduce with increasing scale. The behaviour of multiple jointed masses with different joint spacing is also considered. It is found that despite unchanged roughness, jointed masses consisting of many small blocks have higher peak shear strength than jointed masses with larger joint spacing. These scale effects are related to the changing stiffness of a rock mass as the block size or joint spacing increases or decreases. Economic methods for obtaining scale-free estimates of shear strength are described.

Experimental studies of scale effects on the shear behaviour of rock joints

http://uu.diva-portal.org/smash/get/diva2:1153724/FULLTEXT01

The use of discrete fracture networks for modelling coupled geomechanical and hydrological behaviour of fractured rocks

Reassessing the Joint Roughness Coefficient (JRC) Estimation Using Z2

An experimental study on the progressive shear behavior of rock joints with tooth-shaped asperities

Effect of joint sets on the strength and deformation of rock mass models

The effect of asperity order on the roughness of rock joints

A discrete element model is proposed to examine rock strength and failure. The model is implemented by UDEC, which is developed for this purpose. The material is represented as a collection of irregular-sized deformable particles interacting at their cohesive boundaries. The interface between two adjacent particles is viewed as a flexible contact whose constitutive law controls the material fracture and fragmentation properties. To reproduce rock anisotropy, an orthotropic cohesive law is developed for the contacts, which allows their shear and tensile behaviors to be different from each other. Using a combination of original closed-form expressions and statistical calibrations, a unique set of the contact microparameters are found based on the uniaxial/triaxial compression and Brazilian tension test data of a plaster. Applying the obtained microparameters, joint specimens, made of the same plaster, are simulated, where the comparison of the obtained results to laboratory data shows a reasonable agreement.

/pdf/a-discrete-element-model-for-predicting-shear-strength-and-vk6rr1bkt7.pdf

Zon-Yee Yang

Papers

Reassessing the Joint Roughness Coefficient (JRC) Estimation Using Z2

An experimental study on the progressive shear behavior of rock joints with tooth-shaped asperities

Effect of joint sets on the strength and deformation of rock mass models

The effect of asperity order on the roughness of rock joints

A Discrete Element Model for Predicting Shear Strength and Degradation of Rock Joint by Using Compressive and Tensile Test Data