Abstract: Shear displacement along bedding defects is a well-recognised behaviour when tunnelling and mining in stratified rock. This deformation can affect the durability and integrity of installed rock bolts. In-situ monitoring of rock bolt deformation under bedding shear cannot be accurately derived from traditional strain gauge bolts as sensors are too large and spaced too far apart to accurately assess concentrated displacement along discrete defects. A possible solution to this is the use of fiber optic technologies developed for precision monitoring. Distributed Optic Sensor (DOS) embedded rock bolts were installed in a tunnel project with the aim of measuring the bolt deformation profile under significant shear displacements. This technology successfully measured the 3D strain distribution along the bolts when subjected to bedding shear and resolved the axial and lateral strain constituents in order to determine the deformational geometry of the bolts. The results are compared well with the current visual method for monitoring shear displacement using borescope holes, considering this method as suitable.
Abstract: We developed a non-contact method for the in-situ
monitoring of the thermal forming of glass and Si foils to optimize
the manufacture of mirrors for high-resolution space x-ray
telescopes. Their construction requires precise and light-weight
segmented optics with angular resolution better than 5 arcsec. We
used 75x25 mm Desag D263 glass foils 0.75 mm thick and 0.6 mm
thick Si foils. The glass foils were shaped by free slumping on a
frame at viscosities in the range of 109.3-1012 dPa·s, the Si foils by
forced slumping above 1000°C. Using a Nikon D80 digital camera,
we took snapshots of a foil-s shape every 5 min during its isothermal
heat treatment. The obtained results we can use for computer
simulations. By comparing the measured and simulated data, we can
more precisely define material properties of the foils and optimize
the forming technology.