The Great Glen Fault (GGF) of Northern Scotland is one of the most enigmatic fault structures in the UK. Despite much previous work, its status, longevity and movement history remain controversial. The British Geological Survey (BGS) are currently undertaking a nationwide project aimed at characterising major faults in the UK. ‘UK Structure’ aims to generate a baseline dataset that will meet the needs of various stakeholders requiring information about faulting history and properties in the UK and its impact on national infrastructure, groundwater resources and geodisposal, for example. The Coire Glas project is a hydro pumped storage scheme with the capability to double the current electricity storage capacity of Great Britain. The ambitious and large-scale civil engineering project will involve tunnelling through the GGF in order to connect the lower reservoir (Loch Lochy) with the new upper reservoir. Detailed characterisation of fault rocks encountered during the project will help to better understand the GGF, and has potential implications for future engineering projects. Here we have devised and applied a characterisation workflow to a suite of fault rocks from the GGF. The workflow includes the application of CT during sample preparation, allowing for preparation of an undisturbed and fully orientated section of fault gouge material. Furthermore, detailed petrology of fault rocks is determined using a range of methods including X-ray Diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and optical (cold-cathode) cathodoluminescence (CC-CL). The microstructure of the fault rocks reflects a complex multigenerational fracturing history associated with movement on the GGF, indicated by numerous different phases of carbonate and silicate mineralisation as identified using SEM Mineralogic software. These phases include Mg-siderite cements within fault gouge, and late-stage authigenic kaolinite and calcite cements within fractured ferroan dolomite clasts. In addition to detailed petrological characterisation, we intend to carry out U-Pb dating of calcite crystals within fault rocks to determine the age of calcite mineralisation, thus providing a better understanding of the timing of fault movement.

Localised failure in the form of shear localisation bands is always observed in triaxial tests on rocks and other geomaterials. The deformation inside a shear band is usually much higher than its counterpart in the zone outside the shear band, while stresses inside and outside a shear band are comparable, due to equilibrium conditions across the boundary of the shear band. Inelastic behaviour of the specimen is mainly governed by the behaviour inside shear bands and hence should be considered as true intrinsic properties of the material. Nevertheless, traditional practice in analysing and interpreting triaxial test data usually ignore localisation of deformation by taking averaged measurements of both strains and stresses over the volume of the specimens. As a consequence, the use of stress-strain relationships obtained from triaxial tests to represent behaviour of geomaterials is questionable, given they are the averaged quantities and hence cannot truly represent intrinsic properties of rocks and other similar geomaterials. In this study, an approach considering localised failure is developed and used to correctly interpreting and analysing triaxial test results on rocks. The obtained results on stress and relative displacements between two sides of a shear band are considered intrinsic post-localisation behaviour of rocks. They can be used directly for the development of a new generation of constitutive models taking into account localised nature of failure. Both benefits and practical implications of the proposed new approach for obtaining intrinsic properties of geomaterials are discussed and highlighted.

The Capo d'Orlando is a terrigenous formation outcropping in the northeastern part of Sicily (southern Italy). Its deposition is related to the preliminary erosion of basement metamorphic rocks, and subsequent transport through gravitational processes in different sedimentation ba-sins. This led to the formation of heterogeneous deposits consisting in sandstone banks, locally alternating with pelitic and conglomeratic layers. The present research aims to study the sand-stones at the scale of both intact rock, that was analyzed in laboratory to assess their physical - mechanical properties, and rock mass, through field surveys. The achieved results confirmed that although the sandstones are part of the same geological formation their physical-mechanical features are strongly variable.

Heritage conservation is of great importance to society, particularly in light of the recent increase in fires affecting historical buildings. This study investigates the effects of high-temperature exposure on Pedra de Borriol, a specific type of limestone. This rock has been commonly used in the construction of historical monuments in eastern Spain since the 17th century, and it continues to be utilized today, particularly for ornamental purposes. The study analyzes the effects of high temperatures on the strength, mineralogy, and color of this cretaceous limestone. On one hand, it is known that the strength of rocks decreases with increasing temperatures when subjected to thermal treatment. In the case of the limestone studied in this research, a decrease in strength of over 90% has been observed when exposed to temperatures exceeding 800°C. On the other hand, it has been noted that the color of this rock varies noticeably at different temperatures. The significant color changes are directly linked to the mineralogical composition of the rock. At an exposure temperature of 400°C, the natural color of the rock turns reddish; at 600°C, the color becomes gray, and at 900°C, the rock exhibits a whitish coloration. By considering the three aspects of mineralogy, color, and strength, it becomes possible to assess the impact of a fire on a historical monument constructed with this particular rock. Through this analysis, it is possible to (i) estimate the maximum temperature the material has been exposed to, (ii) evaluate the decrease in strength using non-destructive testing methods such as color changes, and (iii) identify the areas of the building affected by varying degrees of thermal damage. The ultimate objective is to investigate the effects of high temperatures on both the ornamental and structural functions of the rock. The results obtained from this research contribute to the advancement of techniques for assessing thermal damage to historical heritage after a fire