Determination of pipelines laid in rocky ground damage
Background Interaction of rocky ground with pipes leads to the implementation of the metal local plastic deformations, strain aging and macroscopic shape change. All this reduces the resistance to brittle rupture and operation life of pipelines. The first two factors are associated with the embrittlement of the metal and reduction of fracture toughness of the metal. As a result, a dent is generated by the macroscopic shape change in the area of the concentrated load, this dent is a source of stress concentration and the initiation and development of cracks in the pipes. It should be noted that the dent, qualified as invalid in accordance with the requirements of the standard materials, may not reduce the static strength pipes even in the presence of cracks of a certain size. Therefore estimation of the limiting parameters of cracks has a practical interest, causing leakage and destruction of the pipes during subsequent cyclic loading, which is in-dicative for oil pipelines. Aims and Objectives: to assess the degree of damage of the metal oil pipes in their interaction with rocky ground; to substantiate the normalized parameter of risk assessment of damage caused by contact of the pipe with the ground. Methods Solving of the problems based of the known positions of fracture mechanics and experimental data on crack resistance of metals pipes. Results The high degree of stress concentration that occurs in the contact of pipe and solid rocky soils, leads to the realization of metal cracks of different orientation, as well as the V-shaped cracklike defects. The presence of stress concentrators in the pipes decreases the strength and service life of pipelines in several times. Therefore, the compensating elements should be used for the laying of pipelines.