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The utilisation of rock bolting for the support of British coal mine roadways can improve roadway strata conditions and, by permitting a reduction in the density, cross-section or total elimination of steel standing support, can produce considerable savings in roadway support costs. This study reviews worldwide experiences in the use of rock bolt reinforcement techniques to enhance the stability of coal mine roadways. Details of methods of geotechnical design data acquisition and assessment are given as well as a critical study of various empirical, analytical and observational methods of tunnel support design. The use of scale model studies is shown to be particularly effective for the design of rock bolt support systems for coal mine roadways. With reference to numerous case studies, descriptions are given of rock bolt systems available and their suitability to specific mine roadway conditions is discussed. Installation procedures and equipment are also reviewed. It is the author's intention that this study should be used as the basis for further detailed investigation of specific aspects of rock bolt support systems. A number of recommendations are made as to the fields in which further research should be undertaken.

Full scale field trials, carried out during the construction of the Penmaenbach Tunnel in North Wales, have shown that two-speed resin bonded rock bolts are resilient to close proximity blasting. Fully grouted 6m long rock bolts, installed within 0.7m of the tunnel face, have shown no significant signs of distress or failure. Instantaneous loads of up to 40% of the characteristic strength of the bolt were observed together with average residual load losses of 5% of the working load, which compares favourably with the acceptable tolerance of 10% working load stipulated by current practice. Analysis has also shown that rock bolts with low prestress sustain greater vibrations and proportionately higher dynamic load changes during blasting. However, bolts with relatively high prestress loads sustain greater induced loads. Empirical relations have been established to describe rock bolt behaviour in terms of induced vibration and scaled distance. In particular, a predictive equation relating dynamic load changes in the experimental rock bolts to scaled distance, is presented. Calculations based on approximate bolting costs have indicated that cost savings of up to 38% of the total bolting cost could have been effected if the results of this work had been implemented at the design stage. Physical modelling work has confirmed that the distribution of loads in the fixed anchor of a resin bonded bolt are non-linear when both static and impulsive loads are applied to the bolt head. Corroboration of the field results has also been established with respect to the significant influence of initial prestress load on dynamic load change. Complementary finite element modelling work has successfully predicted fixed anchor load distributions under static and dynamic loading conditions. Attempts to establish a detailed relation between distance from blast, magnitude of charge and change in residual load, for low to medium capacity rock anchorages on the West Portal of the tunnel, were thwarted by the poor performance of instrumentation with respect to temperature sensitivity. However, a simplistic approach to analysis has enabled the establishment of a tentative predictive relationship.

The distinct element method (DEM) is a useful tool in rock engineering to model jointed rock masses. To simulate a jointed rock mass realistically, the main challenge is to be able to capture its complex geometry which consists of blocks with various shapes and sizes, and to model the interactions between these blocks. The main contribution of this thesis is the development of novel algorithms in the DEM to model jointed rock masses, namely rock slicing procedures for block generation, and algorithms for contact detection between polygonal blocks in 2-D or polyhedral blocks in 3-D. These algorithms make use of convex optimisation techniques, for which there exist efficient solution procedures. They do not rely on conventional vertex-edge-face hierarchical data structures and tedious housekeeping algorithms. The algorithms have been verified against analytical and numerical solutions, as well as validated against experimental results published in the literature. Among those, the results of DEM simulations were compared against the experimental model tests and numerical simulations of jointed beams carried out by Talesnick et al. (2007) and Tsesarsky & Talesnick (2007) respectively. Emphasis was placed on modelling the stiffness of the block interfaces accurately, and this was accomplished by reinterpreting the laboratory data published by the investigators. The capabilities of the numerical tools are also examined and demonstrated in areas for which the DEM has found practical application. A substantial fraction of this thesis is devoted to illustrating how these tools can assist the engineer in designing support systems; for example, designing the length and spacing of rock bolts and the lining thickness for a tunnel. Algorithms to model rock bolt and lining support were implemented for this purpose. Interesting comparisons with elastic solutions for supported openings were obtained. Further, it is shown that the relative benefit of introducing more rock bolts or thicker lining can be evaluated using the numerical tools with the aid of an interaction diagram. In the final part of this thesis, the case history of the 1963 Vaiont rock slide in Italy is studied. The 2-D analyses led to useful insights concerning the influence of the reservoir water level, the rock mass strength and deformability, and the slide surface shear stiffness. 3-D analyses were undertaken to investigate the influence of the eastern boundary of the slope, and interesting insights were obtained concerning the slope kinematics. Overall, the case study shows that the tools are capable of modelling problems with specific physical and geometrical detail in both 2-D and 3-D.

Current methods for assessing the integrity of ground anchorages during service are primarily restricted to monitoring by load cells or load lift-off testing. Both are expensive and lift-off testing is time consuming and can damage the anchorage construction below the anchor head. Hence, only typically 5-10% of anchorages are monitored in service. As a result, The Institution of Civil Engineers reported that non-destructive test methods for ground anchorages need to be developed as a high priority (ICE, 1992). The Universities o f Aberdeen and Bradford have been conducting research since 1986 to investigate the response o f rock anchorages to dynamic loading arising from blasting operations. Full scale field trials were conducted during the construction of two tunnels in North Wales. An important finding from the research revealed that certain characteristics of the dynamic response of a rock bolt resulting from blasting operations, were similar for different blast sequences. This indicates that the dynamic response o f an anchorage system is dependant on the construction of the anchorage and the characteristics of the co-vibrating rock mass. Consequently, the University of Aberdeen has developed a new non-destructive condition monitoring and integrity assessment system for ground anchorages (GRANIT ™). A range of patent applications have been successful world-wide and the system has been exclusively licensed to AMEC Civil Engineering Limited. The system operates by applying an axial tensile impact load to the free end of an intact anchorage immediately after installation. The resulting vibrational response is monitored by an accelerometer, located at the anchorage head, which produces a datum signature for that anchorage. The condition of the anchorage is then inferred by comparing subsequent response signatures with the datum. A change in the signature indicates that there may be a potential change in the integrity of the anchorage. Artificial Intelligence systems are employed to compare response signatures. As part of the research programme, the author conducted commissioning tests on small scale laboratory test rigs and was responsible for the development of a prototype non-destructive test system, which included a means of applying an impact load and recording the vibrational response. In addition, the author conducted full scale laboratory tests and field trials to investigate the effect of prestress on the dynamic response of ground anchorage systems. As a result, the prototype non-destructive test system has been employed to successfully predict the amount of load within an anchorage installation.

The provision of a safe and economic rock support system is of primary importance for any excavation programme. If the excavation is to be developed by explosives, then the effect of blast forces on the performance of the rock support system must be considered. A review of current literature has highlighted a general lack of information regarding rock anchorage performance under blast loading. With this in mind, a full scale field test programme was undertaken to study the effect of close proximity blasting on resin bonded rock bolts, during the construction of the Pen y Clip Tunnel in North Wales together with a re-analysis of data from a previous study at the nearby Penmaenbach Tunnel. In both cases, accelerometers were used to monitor vibration and hydraulic load cells recorded the changes in rock bolt load during production face blasting. For the Pen y Clip trials, an additional monitoring system was developed which incorporated load cells positioned along the length of specially made experimental rock bolts. Further trials were conducted at an Edinburgh City Centre site to assess the likelihood of damage to temporary, cement grouted rock anchorages whose fixed anchors were positioned as close as 5m from nearby tunnel blasting. These trials involved the measurement of vibrations, both on the anchor head and down specially constructed boreholes, together with lift off load testing. Analysis consisted of the time and frequency domain examination of the signals, recorded on FM magnetic tape, from the three sets of field trials. Resin bonded rock bolts installed in microdiorite and rhyolite were found to be highly resilient to blasting, even those positioned down to lm from full face tunnel blasting. Temporary anchorages in mudstone were more susceptible to blasting but damage could be limited by monitoring of vibrations and careful control of blast parameters. The frequency response of the anchor head was found to be dependent on the characteristics of the anchorage and the nature of the environment in which it was installed. This raises the possibility that the analysis of spectral responses could form the basis of a technique for the non destructive testing of rock anchorages.