Mechanical Shock Load Influence On Adjacent Buried Pipeline And Control Research

As an effective transportation, buried pipeline has more and more close relationship with modern industrial manufacture, agricultural production and ordinary life. While large scales of infrastructure such as highways and railways, the disturbance, caused by machine constructing to surrounding ground of buried pipelines, has taken negative infection on the buried pipeline normal use and safe operation. Once the oil and gas pipeline has operation incidence (rupture, tube explosion, leakage), there would bring out server inducing disaster, pollution to the soil and underground water, huge economic loss and casualty and damage to the social product and the people’s life, besides the direct loss caused by pipeline system damage. So the study on the influence and control of machine construct impact to adjacent buried pipelines has become a key program in Geotechnical Engineering and pipeline safety protection immediately.This dissert made an integrated analysis on the buried pipeline force character in the machine impact loads by theoretic analyzing, finite element numerical simulation and field testing, which could be used to evaluate and handle construct vibration to the adjacent buried pipelines. It was comprised of the following aspects.(1) Quantitative and qualitative illustrating to impact loads, building the impact physic model and deducing the mathematic expression by solving the motion equation had been carried out. Moreover, based on the wave theory, propagation characteristic of vibration waves caused by impact in clay was analized and the influence scope of vibration waves was evaluated. Combined theoretical analysis with numerical simulation, propagation law of vibration waves in attenuate viscoelasticity medium was acquired.(2) The present computational theories and methods about mechanical analysis of buried pipelines was expatiated and the deficiency of popular pipe-soil interaction theoretic analysis model was reviewed. In favor of the contact surface deformation accordance, the elastic solution of soil stress around the buried pipelines was deduced by stress function method. In this way, the relationship between stress around pipeline and section stiffness was built and the methods for calculating soil pressure on rigid and flexible pipelines were unified.(3) Based on the mechanical analysis of buried pipelines, impact loads acting on the pipelines was analyzed in theory for the first time. In view of the Boussinesq equation, mechanical calculate expression of buried pipeline under impact loads on the earth’s surface was established. Also, based on the Mindlin calculate model and elastic ground of boundless beam model, mechanical calculate formula of buried pipeline under impact loads inside the pile was set up. Besides, found on the unit impulse function of δ and Fourier series, ground beam model of Eular-Bernoulli for buried pipeline under impact loads was established and the dynamical response of buried pipeline was solved. The methods could provide theoretical support for analysis of bridge pile foundation construction effecting on buried pipelines.(4) By constructing the3-dimension pipe-soil nonlinear contact finite element model, dynamic response of buried pipelines under impact loads was studied from the aspects of vibration source, pipeline depth, impact energy, the distance between pipeline and vibration source. Furthermore, parametric sensitivity was analized. Through numerical calculation, the relationship between vibration velocity on the ground surface and pipeline deformation was discussed emphatically. According to periodic cycle loads, the accumulative effect of buried pipelines was calculated and analyzed from the aspects of displacement.(5) By the means of field microseism experiments, the construction vibration character and the influence on the adjacent buried pipelines were studied, which compare with the outcome of numerical simulation. Through locating analysis of impact vibration source, the vibration affect area was setted. And it put out a new method for vibration research on bridge pile foundation construction.(6) Based on simulating calculation and field testing, reasonable control standard of vibration caused by punching construction was discussed. By analyzing relative specifications and calculating the pipeline load ability, a control standard was put on desk on vibration caused by punching construction. Besides, pipeline protection and control measures were summarized systematicly from aspects of initiative and passivity control. And the practical application in engineering obtained preferably effect. The achievements in task research may have an immediate utilization in close projects. Also the study method provides reference for developing and researching similar projects.