Development of a Novel Aeration Measurement System to Evaluate Water Treatment Process in a River

A novel aeration measurement system was developed to evaluate the water treatment process in a river to acquire a more comparable dissolved oxygen value even if various types of aerations are tested. The system comprises of DO sensor, water flowmeter, anemometer, PVC pipes, water pump, air compressor pump, and truck tyre tubes. The PVC pipes consisting of a main drainage hole, 5 holes for dissolve oxygen data collection, 1 hole as the location of aerator system, and connectors were designed as the major part of the system by using Computer Aided Design software. The main drainage hole (horizontal pipe) was designed to be 288.5 cm in length, while the measured holes (vertical pipes) were designed to be 45.7 cm in height. By considering a systematic approach, the designed system is hopefully able to solve measuring issue of dissolved oxygen in moving water and to provide a better evaluation of water treatment process.

Prediction Model for Spontaneous Combustion of Coal around Boreholes Using Bedding Gas Drainage

To accurately and reliably predict the time of spontaneous combustion of fractured coal around a borehole induced by gas drainage along the seam, this study performed an orthogonal test taking the No. 10 Coal Mine of Pingdingshan as the research object, in terms of the suction negative pressure and coal seam buried depth. COMSOL Multiphysics was used to model the orthogonal test results, and a multielement statistical analysis of four factors and their relationships with the spontaneous combustion of coal around the borehole and a single-factor analysis in line with the site conditions were performed on the modeling results through multiple regression. The results showed a nonlinear regression relationship between the sealing hole length, sealing hole depth, negative pressure, and coal seam depth and the spontaneous combustion of the coal around the gas drainage borehole; the prediction regression model is significant. Taking the field gas drainage in the No. 10 Coal Mine of Pingdingshan as an example, the relationship between the time of spontaneous combustion of gas drainage and the drainage pressure follows a power of two. When the drainage negative pressure is less than 45 kPa, the coal around the borehole is more likely to undergo spontaneous combustion with increasing pressure, and the sealing hole length has a positive linear correlation with the time of spontaneous combustion of the coal around the borehole. When the sealing hole length is 23 m, the time of spontaneous combustion of the coal around the gas drainage hole is >500 days, and the coal around the borehole does not easily undergo spontaneous combustion. When the sealing depth is 15 m, the time of spontaneous combustion of the coal around the gas drainage hole is 76 days, which is most likely to cause spontaneous combustion.

Mathematical characterization of pile-soil interface boundary for consolidation analysis of soil around permeable pipe pile

Permeable pipe pile is proposed to accelerate the dissipation of excess pore water pressure through drainage holes around the pile circumference into the pile’s cavity. This investigation generalizes the permeable pile-soil interface as an impeded boundary, based on which a mathematical model for soil consolidation around permeable pile is derived. Subsequently, the influence of opening pattern, drainage hole-to-pipe pile radius ratio, and opening ratio on the consolidation efficiency is numerically investigated. A total of 240 numerical cases with different drainage hole-to-pipe pile radius ratio, opening ratio, and hydraulic conductivity ratio are calculated to determine the permeable pile-soil interface parameter using back-analysis, and an approximate expression for interface parameter is obtained. Comparing against experimentally measured excess pore water pressure dissipation, the proposed technique with impeded drainage boundary can provide good evaluations for drainage characteristics at the permeable pile-soil interface and consolidation behavior of the surrounding soil. It is found that the spatial distribution pattern of drainage holes has negligible influence on the consolidation efficiency. Increasing the opening ratio (with constant opening size) or reducing the drainage hole-to-pipe pile radius ratio (with constant opening ratio) can both accelerate the consolidation efficiency.