Multi-turn Pipe Freezing Hydro-thermal Coupling Model Test And The Research Of Optimization Design

Through access to the relevant literature, combing with our current application status of the freezing sinking in the coal sector, using the model tests and numerical simulation method to study the moisture field, the temperature field, as well as the hydro-thermal coupling law under the multi-turn freezing pipe conditions, and then explored to optimize the freezing design of a project instance, these were play a catalytic role for the theoretical research and technological progress of our freezing sinking through the deep alluvium.By the multi-turn pipe freezing model test platform of the Permafrost Institute of Anhui University of Science&Technology, we obtained that:The shortest permafrost cross-lap time was the middle circle tube; the followed were between the outer ring and the middle ring, between the inner ring and the middle ring, between the outer and the inner ring pipes. The law of the distribution of moisture field can be divided into three moisture migration zone:The area within the inner ring tubes and outside the outer ring tubes, soil water content increased by about11%after frozen; the area between the outer and inner ring, the water content of the soil then decreased about9%after frozen; near the area of frozen pipes, the soil water content increased about8%to12%after frozen. Combined with the design parameters of the model test and related conditions, using the large finite element numerical simulation software ADINA to simulate hydro-thermal coupling, we got that the freezing front at the maximum temperature gradient, moisture migration was the most dramatic. In the entire temperature field, the migration of moisture had heterogeneity; the moisture migration was mainly effected by the cooling region of the freezing, the most intense area was the freezing front.According to a coal mine air shaft freezing design parameters, by the numerical simulation method, we preliminary studied the multi-turn pipe freezing optimized design, the distance between the inner ring and the middle ring accounts for0.55to0.62of the distance between the inner and outer rings, it can promote the largest migration of the water at the outer tube, to reduce the freezing pressure of the outer tube; through appropriate extent the freezing time, reducing the average temperature of the frozen wall, could compensate the lack of effective thickness of the frozen wall to improve the freeze wall bearing capacity and reduce costs.