Abstract
Urea-formaldehyde resin (UFR), one of chemical grouts in which the major ingredients are urea-formaldehyde and resin, is widely used in Chinese coal mines grouting. The gel characteristics of urea-formaldehyde resin (UFR) chemical grout under static conditions have been studied by many researchers. However, there is little research carried out on the gel characteristics under shear flow conditions. In fact, chemical grout like UFR keeps in shear flow conditions before gelling in the grouting process. In order to investigate the gel characteristics of UFR in shear flow conditions, an apparatus which consists of a magnetic stirrer and a viscometer was established. Magnetic stirrer was used to shear UFR at different velocity. Then the changes of UFR viscosity could be recorded by viscometer. As a result, the gel characteristics were summarized under different shear rates, and a formula of gelling is derived. The results show that the grouting flow rate influences the gelling time. Faster flow rates will cause longer gelling time, which means that the time for the grout to gel during the flowing process under shear flow conditions is longer than that under static conditions.
Highlights
Chemical grout is widely used to control seepage and leakage, especially in the prevention and treatment of water and quicksand in coal mines
Urea-formaldehyde resin (UFR) has been used to address many difficulties as it has the advantages of low viscosity, good groutability, and good performance in terms of antiseepage and water plugging in a high pressure stratum
In reality, when underground water is in static conditions, the grout flow rate is lower, in which pressure is increased with time [5, 6]
Summary
Chemical grout is widely used to control seepage and leakage, especially in the prevention and treatment of water and quicksand in coal mines. From 2002 to 2007, UFR resin chemical grout has been popularized and applied in the curing of shaft wall fractures and used in water and sand inrush disasters in the east of China. In reality, when underground water is in static conditions, the grout flow rate is lower, in which pressure is increased with time [5, 6]. When underground water is in motion, the grout flow rate is faster, in which pressure is lower at first and increases after a lengthy amount of time [7, 8]. The method specified in this standard test the gel time of grout under static conditions Whether this standard can be employed for UFR still requires further studies [9]. Mathematical Problems in Engineering the flowing characteristics of the UFR chemical grout so as to draw the attention of experts in the field to this problem
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