Analysis of Joint Surfaces with GIS Methods
- Z. Biber (Koméro (RockStudy) Ltd) | G. Szujó (Koméro (RockStudy) Ltd) | V. Gál (Koméro (RockStudy) Ltd) | L. Kovács (Koméro (RockStudy) Ltd)
- Document ID
- International Society for Rock Mechanics and Rock Engineering
- ISRM International Symposium - EUROCK 2020, 14-19 June, physical event not held
- Publication Date
- Document Type
- Conference Paper
- 2020. International Society for Rock Mechanics and Rock Engineering
- shear-strength test, shear-strength test, GIS, 3D modelling, discontinuity, photogrammetry, photogrammetry, GIS, 3D modelling, discontinuity
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- 9 since 2007
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In real rock masses, the discontinuities play a generally significant role in the stability of rock slopes or underground facilities. On a laboratory scale, shear-box tests are most frequently used for determining their rock mechanical features. Using the methodology approved by ISRM multiple-step tests are carried out in our laboratory, without repositioning of core specimens. Constant normal force and gradually increasing shear force is applied to the core at each step. Mechanical behaviour of the joint surface can be calculated following ISRM suggestions, taking into account the continuously changing surface. This methodology however still comprises some uncertainties. One of those is the lack of knowledge on real surface effectively contributing to the shearing process.
The goal of this research is to provide a deeper understanding of the geometrical attributes of rock joints. The core specimen pairs were reconstructed virtually before and after the tests, using digital close-range photogrammetry, then the models were analysed with 3D modelling and GIS software. High resolution 3D textured reconstructions were created and characterized by their real spatial dimensions. By deeper analysing the models the real mechanism of shearing and the mechanical behaviour of infilling materials are expected to be understood more accurately.
Using the joint surface models multiple analysing methods were developed. Firstly, the areas of the fracture surface were separated from the mantle and handled as a relief model in GIS environment. These models can be used for creating high-resolution JRC profiles by objectively defining their line of strike. Then using the pre-shear and post-shear state of the specimens the surface change was determined. Our next goal was to locate the primary contact areas of the specimen pairs in terms of shear-, and normal force. Finally, a new index was developed to describe the surface roughness of rock masses in three dimensions.1 Introduction
In order to determine the shear strength of naturally occurring discontinuities of rock samples and to investigate their mechanical behaviour, the shear box test can be the solution. These measurements were carried out in our rock mechanical laboratory and were executed according to the official ISRM (International Society of Rock Mechanics) suggested method (Muralha et al, 2014).
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