Study On Risk Assessment Technology For River Crossing Construction Of Oil And Gas Pipeline Excavation

With the quickening pace of global oil and gas pipelines construction, scale and level of oil and gas pipelines construction has greatly improved. Meanwhile, the large excavation through the construction is the main type of oil and gas pipeline construction methods because of simple, direct, low construction cost. And, because of the specific hydrological and engineering geological conditions, the large excavation of river-crossing oil and gas pipelines which as the national large-scale construction projects have more difficult than onshore pipeline construction conditions. The oil and gas pipeline construction have the serious influence on people’s life, social stability and the sustainable development of the regional ecological environment. Therefore, it is of significance to study the technology of risk evaluation of the large excavation of river-crossing oil and gas pipelines with the actual situation of river-crossing.In this article, on basis of domestic and foreign relevant information on construction technologies, construction standards and work instructions, possible risk factors are found out, which induce an substandard construction of the large excavation for river-crossing oil and gas pipelines. Then, the fault tree for the construction system of river-crossing oil and gas pipelines is established, and an qualitative analysis is conducted on the fault tree to determine the minimal cut set and structural importance of each basic event. At last, main factors which lead to the failure of the entire system are confirmed.Aimed at actual situation about the large excavation of river-crossing oil and gas pipelines,the basic model of risk assessment is modified and risk assessment model of the the large excavation of river-crossing oil and gas pipelines is established. After studied the risk factors which affect this construction, a relatively perfect index system of risk evaluation is established.The risk assessment is conducted on the construction of large excavation for river-crossing oil and gas pipelines by fuzzy comprehensive evaluation method and BP neural network evaluation method, respectively. Index factor weight at all levels is calculated which applies analytic hierarchy process. And, with specific examples, the applicability of the fuzzy comprehensive evaluation method and BP neural network evaluation method are analyzed by determining the risk level of the excavation phase in the construction of the large excavation for river-crossing oil and gas pipelines. As the BP neural network evaluation method has more applicability than the fuzzy comprehensive evaluation method,the BP neural network evaluation method is used in this article.The model of risk management of river-crossing oil and gas pipelines is studied,the corresponding risk mitigation control measures are made.