PARAMETRIC FLUCTUATIONS OF UNDERGROUND AND ELEVATED OIL PIPELINE

Abstract

Based on the use of the assumptions of the theory of closed cylindrical shells by Vasiliy Z. Vlasov, the authors suggested an analytical method for the study of dynamic instability of pipelines. The nonstationary internal pressure induced by the pumping equipment of the pumping stations is considered as the stimulation source. This pressure excites the longitudinal compressive force, the elastic soil resistance reaction, and the velocity of the flowing fluid. The result of the proposed method is inequalities that take into account the damping properties of the ground and the above factors. By means of these inequalities, it can be determined the upper and lower limits of the region depending on the excitation frequency of the pumping station. And the estimation of the stability loss is reduced to the determination of the value of the natural pipeline frequency. If a point falls into the constructed region, the appearance of parametric resonance is inevitable. Comparison of the instability areas for elevated and underground installation depending on the longitudinal force parameter showed that the shift of the area for the  underground method is towards the increase of the longitudinal force parameter.