This article deals with the casting of concrete and reinforced concrete pipes by vibro-vacuum technique. The existing techniques are investigated, the shortcomings are revealed and the solutions to major issues with the improved techniques were offered. Improvement of a technological process of concrete and reinforced concrete pipes production is an important and current task. Development of such technologies should ensure the required supporting capacity reducing the cost of pipeline construction thereof. In this article the existing ways of molding concrete and reinforced concrete pipes have been evaluated. Their engineering deficiencies in terms of labour-intensity and obtaining the products with increased physical and mechanical characteristics have been identified. The offered solution addressing the problems has been identified, namely, the casting of concrete pipes by vibro-vacuum technique. Pilot studies have confirmed that this method makes it possible to achieve the sufficiently high physico-mechanical characteristics of the products. Tensile strength of vibro-vacuum pipes is 40% higher than that of pipes obtained by layer-by-layer axial compaction.

A new calculation method for the strength of concrete pipes, developed, helps to determine the stresses in the walls of concrete pipes under the combined action of an external (compressing pipe) load and internal pressure from the fluid transported under pressure. An analysis of the nature and magnitude of the stresses is necessary to choose the material of the pipe walls, as well as to establish a possible combination of ultimate external. New formulas make it possible to determine the stresses in the pipe walls under the combined action of an external load and internal pressure. Based on the developed formulas, it was found that the main dangerous stresses in the pipes are tensile stresses. Using the obtained equations allows to determine the range of application of pipes made of modified concrete and to select the necessary concrete strength based on operational loads. There are two methods for determining the bearing capacity of pipeline: three-edge bearing method, in which the maximum breaking load (ultimate), and hydro-static loading method to determine the maximum internal pressure. The design of the test bench for pipes was developed in order to determine the maximum internal pressure on the pipe walls.