Os sistemas de classificação maciços rochosos e as redes neurais artificiais possuem diversas similaridades. Existem características que estão presentes nos dois tipos de sistemas: bases de dados são usadas para o seu desenvolvimento; e pesos são parte da representação do conhecimento. Os principais sistemas de classificação geomecânicas (Sistema Q e RMR) podem ser escritos como representações neurais locais. Tais representações permitem uma melhor compreensão do processo de classificação e identificação de padrões realizado pelas classificações convencionais. Experimentos convencionais foram realizados com modelos de redes neurais não-supervisionados. Os modelos não supervisionados permitiriam uma melhor compreensão da distribuição dos dados no espaço de feições. Um modelo supervisionado para escavações subterrâneas em todo domínio do espaço de feições. Importantes relações entre características foram encontradas. / Rock mass classification systems and artificial neural networks have several similarities. There is some characteristics present in both systems: data bases are used in they development, and weights are part of the knowledge representation. The main rock mass classification systems (Q-system and RMR) can be written as local neural network representations. This representation helps a better understanding of the pattern classification and identification process made by the conventional classifications. Computational experiments were made with unsupervised and supervised neural networks models. Unsupervised models allow a better understanding of the data in the feature space. A supervised model allow to make a mapping of the support type used in underground excavation in all feature space domain. Important relations between domain regions characteristics and type of support used were found.

The paper presents a method of calculating deformation coefficients for any point situated in the overlying rock mass or on the ground surface. This solution was based on the method presented by Sroka and Schober (1982, 1987), taking into account new theoretical achievements and the current results of in situ measurements.

The paper presents a method of calculating deformation coefficients for any point situated in the overlying rock mass or on the ground surface. This solution was based on the method presented by Sroka and Schober (1982, 1987), taking into account new theoretical achievements and the current results of in situ measurements.

Detta examensarbete genomfördes i samarbete med Trafikverket och analyserar möjliga orsaker till avvikelser mellan karaktärisering utförd på kärnborrhål vid förundersökningar, uppförande av ingenjörsgeologisk prognos och karaktärisering och klassificering utförd i tunnel vid byggnadsskedet för Citybanan. Två av projektets delentreprenader utvärderades – Norrströms- och Norrmalmtunneln. Totalt analyserades 4596 löpmeter tunnel (Norrströmstunneln) och 2557 meter (Norrmalmstunneln) i syfte att identifiera varför och vart i processen som avvikelser uppstod. Den utförda studien tyder på att inom de två undersökta delentreprenaderna uppstod en skillnad i resultat mellan karaktärisering utförd i kärnborrhål och karaktärisering och klassificering utförd i tunnel. Övergripande visar resultat från karaktäriseringen i samband med tunnelkartering generellt sämre bergförhållanden jämfört med det som prognostiserats. Skillnaderna  otsvarade sämre förhållande uttryckt i 5 (för Norrströmstunneln) respektive 7,5 enheter (Norrmalm) i RMR-systemet från borrhål till tunnelkaraktärisering. Analysen av det utvärderade resultatet indikerar att avvikelserna mellan karaktärisering på borrkärnor jämfört med karaktärisering och klassificering utförd i tunnel antagligen till viss del beror på den använda metodiken vid karaktärisering och klassificering av bergkvaliten med RMR- och Q-systemet. Detta på grund av att parametrarna i systemen inte bestäms på exakt samma sätt vid karaktärisering i förundersökningsskede och karaktärisering och klassificering i byggnadsskede. Dessutom indikeras att anvisningarna för karteringsrutiner vid karaktärisering och klassificering hanteras olika av karterande geologer vid tunneldrivning. Baserat på resultaten från den utförda analysen diskuteras även om det för vissa parametrar för karaktärisering och klassificering finns ett behov av uppdatering i den använda metodiken. Detta för att få förundersökningsprocessen att samspela med det arbete som sker i en tunnel. Resultaten tyder också på att geologerna vid tunnelkartering har en tendens till att kartera sämre bergförhållanden jämfört med det som är prognostiserat samt att vissa egenskaper hos berget kan vara lättare att beskriva på plats i tunneln än vid karaktärisering av berget från en borrkärna. Genom att harmonisera processen för beskrivning av ingående parametrar i de system som används vid karaktärisering mellan förundersökning och karaktärisering och klassificering i byggskede kan skillnader mellan stegen reduceras och risken för prognosavvikelser kan minska för tunnelprojekt i framtiden. / This thesis was carried out in cooperation with the Swedish Transport Administration and analyzes the possible causes of differing rock mass quality assessed in boreholes, engineering geological forecast and tunnel mapping. Two contracts from the City Line project where investigated - in total has 4596 meters (the Norrström tunnel) and 2557 meters (the Norrmalm tunnel) of tunnel mapped during construction been analyzed. The purpose was to identify the reason and where differences in the process of rock evaluation arose. The performed study indicates that in the two investigated tunnels it arose a difference in the results between the characterization performed in boreholes and the subsequent geological forecast compared with the characterization in the tunnel. The assessed rock mass quality became generally successively poorer as the process progresses. This was particulary the case when comparing the geological forecast with tunnel mapping during construction The differences corresponded to a difference of a downgrade of 5 (for the Norrström tunnel) and 7,5 units (the Norrmalm tunnel) in the RMR-system from bore holes to tunnel mapping. The analysis of the evaluated results indicates that the differences between the characterization of boreholes and geological forecasts compared to the characterization and classification performed in the tunnel is probably due to the methodology in the characterization and classification of rock quality with the RMR- and Q system. This is because the parameters of the  ystems is not determined exactly in the characterization of the preliminary investigation stage and the characterization and classification in the construction stage. Also the instructions for mapping routines for the characterization and classification are handled differently by the mapping made by geologists during tunneling. Based on the results of the analysis it is recommended that the way in which some parameters in the systems of characterization and classification of rock are determined should be updated. This is in order to standardize the process for characterizing the rock mass when mapping boreholes, creating geological forecast and conducting tunnel mapping. It is also indicated  that geologists tend to conservatively scale down the rock quality in the tunnel and that certain features of the rock is easier to determine in the tunnel than during characterization of bore holes. By harmonizing the description of parameters of the systems used in the characterization of bore holes and characterization and classification in the construction stage, differences between the steps can be reduced for projects in the future.

Vid en ombyggnation av Henriksdals reningsverk har ett vertikalschakt utformats och anlagts. Under berguttaget tillämpades extensometermätningar för att följa upp deformationer i en bergpelare mot en befintlig tunnel. Mätningar utfördes automatiserat och regelbundet. För uppföljning av deformationer tillämpades tre larmnivåer avgränsade av två larmgränser vid 1.0 mm samt 3.0 mm deformation och var förbundna till olika motåtgärder. Målet med detta arbete harvarit att studera hur tillämpade larmgränser har presterat relativt dokumenterade och prognostiserade deformationer ur ett sannolikhetsbaserat perspektiv. Samt vid behov formulera och föreslå nya larmgränser. En litteraturstudie om modellering av bergmassor samt mekaniska egenskaper hos förekommande bergmassa av gnejs genomfördes. Därefter modellerades objektet för vidare numerisk analys genom FEM i Plaxis 3D. Med grund i uppställd modell kunde in-situ spänningsfältet skattas och modellen optimeras. En känslighetsanalys för bergmassans hållfasthetsparametrar utfördes och de fyra mest känsliga parametrarna: γ, ν, σci, Qbas, applicerades statistiskt i efterföljande studier. Föreslagna och tillämpade larmgränser studerades genom utförande av Monte Carlo-simuleringar. Använda deformationsbaserade larmgränser återfanns inte vara tillfredsställande och nya individuella töjningsbaserade gränsvärden framställdes. De ursprungliga deformationsbaserade larmgränserna resulterade för längre mätankare i utlösta larm och visades vara ouppnåeliga för kortare mätankare. En resulterande sannolikhet för överskridande av föreslagna varningsgränser vid dragtöjning skattades till storleksordningen 10−2 till 10−1 samt för stoppgränserna vid dragtöjning till 10−4. Sannolikheterna för överskridande av föreslagna larmgränser vid trycktöjning var inte möjliga att uppskatta för det studerade fallet. / During a rebuild of Henriksdal wastewater treatment plant, a vertical rock shaft was constructed. During the excavation, extensometers were used for monitoring deformations in a rock pillar against an existing tunnel. Measurements were automatically and regularly performed. Three alarm levels for follow up of the deformations were used and associated with different counter measures. The alarm levels were divided by two alarm limits at 1.0 mm and 3.0 mm deformation. The goal with this work was to study how the applied alarm limits from a probabilistic point of view have performed relative to obtained and forecasted deformations. And, if necessary, propose new alarm limits. A literature study about modeling of rock masses and mechanical properties of the occurring gneiss at site was performed. The object was thereafter modeled for further numerical analyzes using FEM in Plaxis 3D. Based on the performed model, the in-situ stress field could be estimated,and the model was further optimized. A sensitivity analysis of the rock mass strength parameters was conducted and the four most sensitive parameters: γ, ν, σci, Qbas, were applied as probabilistic in the following studies. Proposed and applied alarm limits were studied through Monte Carlo simulation. Applied deformation-based alarm limits were found not to be sufficient and two new strain-based were prescribed. The deformation-based limits were for the longer extensometer anchors resulting in triggered alarms and were only considered to be applicable for anchor lengths between 3.0 to 5.0 m. The probability of exceeding the proposed warning limits for tensile strain was estimated to be of a magnitude 10−2 to 10−1 and for the stop limits to be of a magnitude 10−4. The probabilities of exceeding the proposed alarm limits during compressive strain were not possible to estimate for the studied case.

Determination of the subsurface geology is very important for the rock quarry industry. This is primarily done by drilling and mapping of the surface geology. However in Sweden the bedrock is often completely covered by Quaternary sediments making the prediction of subsurface geology quite difficult. Incorrect prediction of the rock-mass quality can lead to economic problems for the quarry. By performing geophysical measurements a more complete understanding of the subsurface geology can be determined. This study shows that by doing 2D-parallel data sampling a 3D inversion of the dataset is possible, which greatly enhances the visualization of the subsurface. Furthermore the electrical resistivity technique together with the induced polarization method proved to be very efficient in detecting fracture frequency, identification of major fracture zones, and variations in rock-mass quality all of which can affect the aggregate quality. With this technique not only the rock-mass quality is determined but also the thickness of the overburden. Implementation of geophysics can be a valuable tool for the quarry industry, resulting in substantial economic benefits. / QC 20101118

This thesis analyzes the potential systematic errorin the characterization of the rock mass quality in borehole and tunnel mapping. The difference when assessing the rock mass quality refers to the fact that the characterization performed on drilled rock cores are commonly done on-meter length, while the tunnel section can be up to 20-25 m wide. At the same time, previous studies indicate that the engineering geologist tends to characterize the rock mass quality during tunnel excavation with a conservative estimation of the parameters defining the rock mass quality to ensure a sufficient rock support. In order to estimate this possible systematic error produced by the size difference when assessing the rock mass quality, a simulation was performed within a geological domain, representative of Stockholm city. In the simulation, each meter of the tunnel section was given a separate value of the rock mass quality, randomly chosen from a normal distribution representative for the studied geological domain. The minimum value was set to represent the characterized rock mass quality for that tunnel section. The results from the simulation produced a systematic error due to the difference between the geological domain, reproducing the borehole mapping, and the simulated values, representing the tunnel mapping. The results showed a systematic error in the RMR basic index around 15 points in average, which compared to the difference of 5-7 points obtained in Norrström and the Norrmalm tunnels in the Stockholm Citylink project recently constructed, are found to be excessive. However, in the simulation, it was assumed that (1) the results obtained were the same in the bore hole mapping and in the tunnel mapping, (2) with the only difference of the engineer geologist assigning to the tunnel section the lowest RMR basic value, and (3) that there was no spatial correlation between the quality RMR basic index. After analyzing the three assumptions the simulation was based upon, the absence of spatial correlation was found to be the most significative, which indicate that spatial correlation in rock mass quality needs to be included if a more correct value should be obtained.

In the construction of a tunnel, the characterization of the rock mass is performed in three different steps, in the pre-investigations, in the engineering geological forecast and in the tunnel mapping during construction. There has in previous work been observed that discrepancies exist between the results from these different steps, with a tendency to assign poorer rock mass quality in the tunnel mapping than in the pre-investigations and in the engineering geological forecast. One example is the work done by Kjellström [1] on the Cityline where the divergence in rock mass quality was analyzed between the different steps. If a divergence exists between the engineering geological forecast and the actual conditions observed in the tunnel mapping, it will influence both planning and budget. It is therefore important that the engineering geological forecast is as close as possible to the actual rock mass conditions in the field. The aim of this thesis was, using the case study of the Northern Link, to analyze those discrepancies in the rock mass quality estimated in the characterization and in the classification between the mapping of drill cores, the engineering geological forecast and the tunnel mapping thus complementing the work by Kjellström [1]. The aim was also identifying which parameters included in the Q-system that causes these discrepancies The analysis of the results showed that it is difficult to make the engineering geological forecast and the actual mapping match for every single meter, but that the overall correlation between them was good. The methodology used in the characterization and classification in the different phases (drill-core mapping, engineering geological forecast, tunnel mapping) may to some extent explain this divergence. The parameters Jr, Jn and Ja, included in the Q-system were the ones identified as having the largest influence on the discrepancies. In future work, it is recommended that focus is given on these parameters. A way to improve future engineering geological forecast for tunnel contracts would be to have a better follow up of the engineering geological forecast and to have standardized guidelines on how to assess clearly the value of the Q parameters in each phase (for the drill cores as well as for the actual mapping). The reduction of those differences would then lead to a better planning and budget management in future tunnel projects in Sweden.

La conception des ouvrages de génie civil dans les massifs rocheux fracturés nécessite une connaissance de leur comportement lors des travaux. Les ma ssifs fracturés sont généralement très complexes et représentés par des matrices et des discontinuités rocheuses. Cette thèse a pour objectif d'étudier le comportement mécanique du massif du futur tunnel de St Béat. La thèse est divisée en trois parties. Nous étudions tout d'abord les phénomènes prépondérants et les facteurs agissant sur le comportement mécanique des massifs rocheux. Dans la seconde partie, nous effectuons séparément des études expérimentales sur le comportement mécanique de la matrice et des discontinuités rocheuses. Enfin, dans la dernière partie, nous présentons une modélisation en 2D du comportement du massif fracturé lors du creusement du tunnel. L'étude expérimentale s'appuie sur des marbres rencontrés sur le site du tunnel. Le comportement de la matrice rocheuse est étudié à partir des essais de compression triaxiale sur des échantillons de roche saine. L'évolution de l'endommagement est caractérisée à l'aide des mesures de vitesses de propagation des ondes élastiques. Une enveloppe de rupture selon le critère linéaire de Mohr-Coulomb est proposée pour la matrice rocheuse. Le comportement au cisaillement des discontinuités naturelles est ensuite étudié sous différentes conditions de chargement (contrainte normale constante et rigidité normale imposée). La mesure de topographie des surfaces des discontinuités avant et après chaque essai mécanique permet de déterminer les paramètres statistiques de la rugosité. L'influence de la contrainte normale, la rigidité normale imposée, la rugosité initiale et la vitesse de cisaillement sur le comportement des discontinuités est mise en évidence. Des lois de comportement pertin entes sont proposées pour chaque type d'essais.Les caractéristiques mécaniques obtenues sont alors introduites dans le code de calcul UDEC afin de modéliser le comportement du massif en présence du tunnel, sous différentes conditions aux limites. La réponse en terme de déformations et de contraintes induites autour du tunnel est analysée / The design of civil engineering structures in fractured rock masses requires knowledge of their mechanical behavior. The fractured rock masses are usually very complex and separated in matrix and rock discontinuities. This thesis aims to study the mechanical behavior of St Beat tunnel rock mass. The thesis is divided into three parts. We study first the predominant phenomena and factors affecting the mechanical behavior of rock masses. In the second part, we perform separately experimental studies on the mechanical behavior of matrix and rock discontinuities. Finally, in the last section, we present a 2D model of the fractured rock mass behavior during the digging of the tunnel. The experimental study is based on the marbles encountered on the future tunnel site. The rock matrix behavior is studied using triaxial compression tests on intact rock samples. The damage evolution is characterized using propagation velocities measurements of elastic waves. A failure envelope by Mohr-Coulomb linear criterion is proposed for the rock matrix. The shear behavior of natural discontinuities is investigated under different loading conditions (normal stress or constant normal stiffness imposed). The discontinuities surfaces topography is measured before and after each mechanical test to determine the roughness statistical parameters. The influence of the normal stress, the normal stiffness, the initial roughness and the shear rate on the discontinuities behavior is demonstrated. A behavior law is proposed for each type of test.The mechanical properties obtained are introduced into the code UDEC to model the rock mass behavior with the presence of the tunnel, under different boundary conditions. The response in terms of deformations and stresses induced around the tunnel is analyzed

The geological disposal of nuclear waste, in underground openings and the long-term performance of these openings demand a detailed understanding of fundamental rock mechanics. A full scale field experiment: Äspö Pillar Stability Experiment was conducted at a depth of 450 m in sparsely fractured granitic rock to examine the rock mass response between two deposition holes. An oval shaped tunnel was excavated parallel to the σ3 direction to provide access to the experiment and also provide elevated stress magnitudes in the floor. In the tunnel floor two 1.75-m diameter 6-m deep boreholes were excavated so that a 1-m thick pillar was created between them. In one of the holes a confinement pressure of 700 kPa was applied and in the other displacement transducers were installed. The pillar volume was monitored by an Acoustic Emission System. Spatially distributed thermocouples were used to monitor the temperature development as the pillar was heated by electrical heaters. The excavation-induced stress together with the thermal-induced stress was sufficient to cause the wall of the open borehole to yield. The temperature-induced stress was increased slowly to enable detailed studies of the rock mass yielding process. Once the rock mass loading response was observed, the rock mass was unloaded using a de-stress slotting technique. This thesis focuses on the in-situ study of the rock mass response to coupled mechanical thermal loading and thermal-mechanical unloading. The experiment, its design, monitoring and observations are thoroughly described. An estimate of the yielding strength of the rock mass is presented and compared with laboratory test and results from other rock mass conditions reported elsewhere in the open literature. General conclusions about the effect of the confining pressure and the observations from the unloading of the pillar are also presented. Important findings are that the yielding strength of the rock mass has been successfully determined, low confinement pressures significantly affects the onset of yielding, the primary mode of fracture initiation and propagation is extensional, no significant time dependency of the yielding process was observed. The unloading studies also indicated that what appeared to be shear bands likely was a propagating zone of extensile failure that weakened the rock so that displacements in the shear direction could occur. / <p>QC 20100622</p>