Influence of degree of interlock on confined strength of jointed hard rock masses
The strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks. The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and slide along the block forming joints. The Hoek–Brown (HB) failure criterion and th...
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| Format: | Article |
| Language: | English |
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Elsevier
2020-12-01
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| Series: | Journal of Rock Mechanics and Geotechnical Engineering |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674775520301098 |
| _version_ | 1819275311870640128 |
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| author | Navid Bahrani Peter K. Kaiser |
| author_facet | Navid Bahrani Peter K. Kaiser |
| author_sort | Navid Bahrani |
| collection | DOAJ |
| description | The strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks. The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and slide along the block forming joints. The Hoek–Brown (HB) failure criterion and the geological strength index (GSI) were developed based on experiences from mine slopes and tunneling projects in moderately to poorly interlocked jointed rock masses. It has since then been demonstrated that the approach to estimate the HB strength parameters based on the GSI strength scaling equations (called the ‘GSI strength equations’) tends to underestimate the confined peak strength of highly interlocked jointed rock masses (i.e. GSI > 65), where the rock mass is often non-persistently jointed, and the intact rock blocks are strong and brittle. The estimation of the confined strength of such rock masses is relevant when designing mine pillars and abutments at great depths, where the confining pressure is high enough to prevent block rotation and free sliding on block boundaries. In this article, a grain-based distinct element modeling approach is used to simulate jointed rock masses of various degrees of interlock and to investigate the influences of block shape, joint persistence and joint surface condition on the confined peak strengths. The focus is on non-persistently jointed and blocky (persistently jointed) rock masses, consisting of hard and homogeneous rock blocks devoid of any strength degrading defects such as veins. The results from this investigation confirm that the GSI strength equations underestimate the confined strength of highly interlocked and non-persistently jointed rock masses. Moreover, the GSI strength equations are found to be valid to estimate the confined strength of persistently jointed rock masses with smooth and non-dilatant joint surfaces. |
| first_indexed | 2024-12-23T23:22:19Z |
| format | Article |
| id | doaj.art-737721d95f4647c293363d9c87390cbe |
| institution | Directory Open Access Journal |
| issn | 1674-7755 |
| language | English |
| last_indexed | 2024-12-23T23:22:19Z |
| publishDate | 2020-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Rock Mechanics and Geotechnical Engineering |
| spelling | doaj.art-737721d95f4647c293363d9c87390cbe2022-12-21T17:26:18ZengElsevierJournal of Rock Mechanics and Geotechnical Engineering1674-77552020-12-0112611521170Influence of degree of interlock on confined strength of jointed hard rock massesNavid Bahrani0Peter K. Kaiser1Department of Civil and Resource Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Corresponding author.Bharti School of Engineering, Laurentian University, Sudbury, Ontario, CanadaThe strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks. The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and slide along the block forming joints. The Hoek–Brown (HB) failure criterion and the geological strength index (GSI) were developed based on experiences from mine slopes and tunneling projects in moderately to poorly interlocked jointed rock masses. It has since then been demonstrated that the approach to estimate the HB strength parameters based on the GSI strength scaling equations (called the ‘GSI strength equations’) tends to underestimate the confined peak strength of highly interlocked jointed rock masses (i.e. GSI > 65), where the rock mass is often non-persistently jointed, and the intact rock blocks are strong and brittle. The estimation of the confined strength of such rock masses is relevant when designing mine pillars and abutments at great depths, where the confining pressure is high enough to prevent block rotation and free sliding on block boundaries. In this article, a grain-based distinct element modeling approach is used to simulate jointed rock masses of various degrees of interlock and to investigate the influences of block shape, joint persistence and joint surface condition on the confined peak strengths. The focus is on non-persistently jointed and blocky (persistently jointed) rock masses, consisting of hard and homogeneous rock blocks devoid of any strength degrading defects such as veins. The results from this investigation confirm that the GSI strength equations underestimate the confined strength of highly interlocked and non-persistently jointed rock masses. Moreover, the GSI strength equations are found to be valid to estimate the confined strength of persistently jointed rock masses with smooth and non-dilatant joint surfaces.http://www.sciencedirect.com/science/article/pii/S1674775520301098Rock mass strengthDegree of interlockNon-persistently jointed rock massBlocky rock massGeological strength index (GSI)GSI strength equations |
| spellingShingle | Navid Bahrani Peter K. Kaiser Influence of degree of interlock on confined strength of jointed hard rock masses Journal of Rock Mechanics and Geotechnical Engineering Rock mass strength Degree of interlock Non-persistently jointed rock mass Blocky rock mass Geological strength index (GSI) GSI strength equations |
| title | Influence of degree of interlock on confined strength of jointed hard rock masses |
| title_full | Influence of degree of interlock on confined strength of jointed hard rock masses |
| title_fullStr | Influence of degree of interlock on confined strength of jointed hard rock masses |
| title_full_unstemmed | Influence of degree of interlock on confined strength of jointed hard rock masses |
| title_short | Influence of degree of interlock on confined strength of jointed hard rock masses |
| title_sort | influence of degree of interlock on confined strength of jointed hard rock masses |
| topic | Rock mass strength Degree of interlock Non-persistently jointed rock mass Blocky rock mass Geological strength index (GSI) GSI strength equations |
| url | http://www.sciencedirect.com/science/article/pii/S1674775520301098 |
| work_keys_str_mv | AT navidbahrani influenceofdegreeofinterlockonconfinedstrengthofjointedhardrockmasses AT peterkkaiser influenceofdegreeofinterlockonconfinedstrengthofjointedhardrockmasses |