EXPERIMENTAL STUDY OF SOIL THAWING AROUND SHALLOW SEWAGE PIPELINES IN WINTER

Introduction. The article addresses issues related to the thermal interaction of sewage pipelines (with complete and incomplete filling) with soils characterized by deep seasonal freezing up to three or more meters in areas with severe climate. Sewage pipelines represent one of the main elements of the water disposal system, determining its reliability and efficiency. To reduce the costs for the construction of sewage pipelines, it is proposed to reduce the depth of pipe laying, i.e. to lay pipelines in a layer of frozen soil. The conducted experimental studies of the interaction between a pipeline and frozen soil revealed conditions under which it is possible to lay pipes in a layer of frozen soil. Methods. The purpose of this study was to determine experimentally the size of the talik around a pipeline laid in frozen soil, with heated water passing through, with the pipeline filling of 0.5 where the water flow covered the full cross-section. To determine the size of the talik, a series of laboratory experiments were carried out. The paper provides a description of the corresponding experimental setup. Results. The authors present results of the laboratory experiments aimed to determine the size of the talik around a pipeline operating with different degrees of filling. They established that in a pipeline where the water flow covers full cross-section, the contours of thawed soil are close to a circumference; in a pipeline with the filling h/d = 0,5, the talik is egg-shaped. According to the results of a comparative analysis of the talik sizes obtained experimentally and by calculations, the actual talik sizes exceed the calculated values by 10–16%.