RMR, Rock Mass Rating, is one of the famous rock classifications. However, RMR was proposed empirically and absolutely depends on the experience of engineer. Therefore, engineering verification is needed for RMR system itself. In this study, the factor analysis and the multiple regressions were performed in order to evaluate the validity of rating factor of RMR. Also numerical analysis was carried out using the FLAC based on Taguchi method, a kind of robust designs, in order to examine the support of tunnel corresponding to the revaluated RMR. As the result of the analysis new RMR was proposed with five minimized factors of intact rock strength, RQD, spacing, persistence and roughness of discontinuities.

RMR est un des procedes de la classification du roc qui sont generalement utilises. Mais RMR s'appuie sur l'experience et se absolument soumet à l'experience d'ingenieur. Il est donc necessaire de verifier techniquement sur le système de RMR. Dans cet etude, on met à execution l'analyse du facteur et la regression multiple pour evaluer la convenance de la cause de classification de RMR. De même, pour evaluer le support du tunnel selon RMR reestime, on a execute l'analyse de la valeur numerique par FLAC qui se base sur la lois de Taguchi, laquelle est une sorte de système du plan robuste. Selon le resultat de la regression multiple, il est propose de nouvel RMR à partir de l'intensite de roc intact, RQD, l'espacement, la persistance et la rugosite RMR ist eine der weit benutzten klassifikationen fuer die felsenstuecke. Da aber RMR erfahrungsmaessig ist und ueberwiegend von der persoenlichen Erfahrung eines Ingenieurs entschieden ist, ist es mit Sicherheit notwendig, das RMR-system selbst technisch zu ueberpruefen. In diesem studium waren die faktorenanalyse und mehrfachregressionanalyse durchgefuehrt, um die gerechtigkeit der klassifikationenfaktoren von RMR zu bewerten. Ferner war noch eine numerische analyse mit benutzung von FLAC aufgrund der Taguchi-methode, eine art technik der robust design, eingefuehrt, um die tunnelstuetze infolge der neubewertung von RMR unterzusuchen. Gemaess der mehrfach regression analyse wurde eine neue RMR, die sich aus 5-eingeschraenkten faktoren wie intact rock strength, RQD, spacing, persistence und roughness von discontinuities zusammensetzen, in vorschlag gebracht.

Introduction

In RMR, a discontinuous rating is applied after the characteristic value of each classification element is grouped in certain categories. Since the demarcation of rating for each element depends entirely on the personal experience of RMR proposer, the proficiency of a technician in charge of classification can exercise a decisive impact upon the outcome, leading frequently to inconsistency even from the planning stage on. By means of immediate testing or survey, the intact rock strength and RQD are rated just as 35 out of total 100 points of RMR at the most, while 65 points are rated for spacing and state of discontinuities and state of groundwater, which is, however, only a rough assumption due to limited access to tunnels at the stage of executable drawing until it may be corrected by observing the blind end of tunnels, a factor that can exert a critical influence upon determination of RMR. It would be hard to maintain the consistency of RMR because it usually differs depending on accessibility to the inspection site and, moreover, on proficiency and experience of inspector. It should also be noted that proposer allocates the scores by factor empirically.

This content is only available via PDF.
You can access this article if you purchase or spend a download.