Analysis of Aseismatic Reliability for Gas Pipeline Network System in Large-Scale Gas Field

摘要

A method for calculating aseismatic reliability of gathering and transferring pipeline network in large-scale gas field is put forward. Taking the maximal seismic intensity S that might occurred during the design service life in the engineering site of gas gathering and transferring pipeline as seismic loads and the fortification intensity ld that is determined during pipelines design as structure resistance, this paper comes up with random reliability analysis model of pipeline to predict the seismic damage. Under the same geological damage environment, pipelines in network are of failure dependency. Aseismatic reliability of pipelines can be expressed with the occurring probability of geological disasters like fault rupture, sand liquefaction, slippage and so forth. For avoiding the NP hard problem caused by the calculation of network reliability, the paper applies breadth first search technology of graph theory to propose the algorithm for determining probability of connectivity reliability for the multi-source and multi-terminal network, and combines it with Monte Carlo simulation to apply to the aseismatic reliability calculation of super-large gas pipeline network. On the basis of the result, the safety of the system will be analyzed and assessed. This method is also able to assess the operation condition of pipeline network after earthquake quickly and constitute reconditioning plan for pipeline network to reduce the earthquake-induced disasters. This paper takes a gas field in western China with 35 pipelines, 4 gas gathering stations and 3 industrial users as example to give the detailed process of the calculation of seismic reliability for pipeline network under the impact of a serious seism at seven magnitudes, analyses the sensitivity and critical importance of pipeline network system and find out the corresponding links of aseismatic weakness. The example demonstrates the simplicity, validity and practicability of this method.