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MULTIPLE UNDERGROUND EXCAVATIONS FOR various purposes including transportation tunnels, repositories for nuclear waste disposal and other types of waste, facilities for oil and gas storage, mining, etc., are under development [...]

ARISING DEMAND FOR UNDERGROUND transportation and resource management has led to the development of many more subterranean projects (deep foundations, tunnels, utility corridors, etc.), which are constructed at larger scales, [...]

Implementing sustainable field training for geology and geological engineering is mutually beneficial for students and industry. Nicholas Vlaehopoulos, professor in the civil engineering department, and Efrosyni-Maria Skordaki, geosciences research staff, [...]

The uniaxial compressive strength (UCS) test is a key tool used by the geotechnical industry to determine the strength and stiffness behavior of intact rock. A fundamental procedure in the process of these experiments is strain response measurement. The standard method of measuring UCS test strain response is to use discrete strain measuring devices such as extensometers or electric strain gages, or both, at the mid-height of a specimen. However, by using a novel technique of integrating distributed optical strain sensing with UCS testing, a high-density full-field strain response of UCS specimens can be measured. This article presents a novel device that can be used as a turnkey solution for installing optical strain sensors to the exterior of UCS specimens for the benefit of measuring full-field specimen strain during UCS testing.

A recent research campaign at a Canadian nickel-copper mine involved instrumenting a hard rock sill drift pillar with an array of multi-point rod extensometers, distributed optical fibre strain sensors, and borehole pressure cells (BHPCs). The instrumentation spanned across a 15.24 m lengthwise segment of the relatively massive granitic pillar situated at a depth of 2.44 km within the mine. Between May 2016 and March 2017, the pillar's displacement and pressure response were measured and correlated with mining activities on the same level as the pillar, including: (1) mine-by of the pillar, (2) footwall drift development, and (3) ore body stoping operations. Regarding displacements of the pillar, the extensometers provided high temporal resolution (logged hourly) and the optical fibre strain sensors provide high spatial resolution (measured every 0.65 mm along the length of each sensor). The combination of sensing techniques allowed centimetre-scale rock mass bulking near the pillar sidewalls to be distinguished from microstrain-scale fracturing towards the core of the pillar. Additionally, the influence and extent of a mine-scale schistose shear zone transecting the pillar was identified. By converting measured rock mass displacement to velocity, a process was demonstrated which allowed mining activities inducing displacements to be categorised by time-duration and cumulative displacement. In over half of the analysed mining activities, displacements were determined to prolong for over an hour, predominately resulting in submillimetre cumulative displacements, but in some cases multi-centimetre cumulative displacements were observed. This time-dependent behaviour was more pronounced within the vicinity of the plumb shear zone. Displacement measurements were also used to assess selected support member load and elongation mobilisation per mining activity. It was found that a combined static load and elongation capacity of reinforcing members was essential to maintaining excavation stability, while permitting gradual shedding of stress through controlled pillar sidewall displacements.

A novel catalytic material (mesoporous TiO2films) for the cathodic detection of hydrogen peroxide in air‐saturated aqueous solution is described. The immobilization of glucose oxidase (GOD) as enzyme model onto the TiO2electrode provides an efficient biosensor for the amperometric detection of glucose at −0.15 V (vs. SCE). GOD molecules were immobilized in an inorganic laponite gel and cross‐linked by glutaraldehyde. The highest sensitivity and detection limit were 3.33 mAM−1cm−2and 15 μM, respectively. In addition different procedures of enzyme immobilization including cross‐linking with glutaraldehyde and physical entrapment in a functionalized polypyrrole film have been compared.