Physical modeling of failure process of the excavation in horizontal strata based on IR thermography

In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.

Analyzing capacity of a consumer-grade infrared camera in South Africa for costeffective aerial inspection of building envelopes

Prohibitive equipment cost and certain export regulations are the major obstacles to the widespread adoption of infrared(IR)thermography when evaluating building envelopes.In this work,we propose the use of an affordable and easily available camera as a first step of making the technology accessible.Combined with image post-processing,we hypothesize that a low-cost,low-resolution,and consumer-grade device can provide an economic alternative for the periodic evaluation of building envelopes.Following a market survey,the Seek Thermal Compact(STC)was chosen for evaluation.The STC was able to accurately measure the temperature of surfaces and distinguish small thermal anomalies(3 mm in diameter),and the IR images can be post-processed to reasonably estimate the anomaly areas.The STC was particularly effective when images were taken within 1.75 m from the surface.The 1.75 m distance did not pose a challenge in this study,as the goal was to mount the selected IR camera on an unmanned aerial vehicle for the surveys.The small size and weight of the STC were also useful.The results from the analysis of the capability of the STC and the image post-processing techniques may help form the basis of future investigations aiming at lowering the cost of building thermographic surveys.