Representing spalling in rock excavations with BBM
Series: BeFo report ; 212Publication details: Stockholm : Stiftelsen bergteknisk forskning. BeFo, 2021Description: 54 sOther title:- Representation av spänningsinducerade brott i tunnlar och bergrum med BBM
Spalling occurs in many different types of projects in rock masses in Scandinavia, including projects in the mining, infrastructure, and storage sectors. Spalling can be problematic for these projects as it may change the profiles of the excavations and transmissivity of the surrounding rock mass. However, numerical modelling of spalling is complex. Typically, continuum models are used with strain softening constitutive models, but they are only a proxy for spalling. They are unable to capture the mechanisms underlying spalling, and they therefore work best as back analysis. This project studies the suitability of a new modelling technique to represent spalling in Scandinavia. The technique is called “Bonded Block Modelling” (BBM) and represents the rock mass as a conglomerate of blocks. Rock mass damage is represented by breakage of the contacts between blocks. The focus of this study is to give advice to practitioners who wish to use BBM in the future, through a literature review and an application of BBM to laboratory tests and in situ spalling of an actual case from LKAB’s Malmberget Mine.