| There are abundant oil and gas resources at the shallow-sea area of north Liaodong Bay,which has great potential development value. While the seabed stability is the basis of ocean development,in this thesis,based on the sufficient study of geohazards of oil and gas resources development area of Liaodong Bay,the seabed stability is synthetically evaluated.The forming and developing of geohazards is closely related to the environment. This thesis discusses the geohazards environment backgrounds from the next 6 aspects,such as hydrometeor,topography and geomorphy,deposited environment,acoustic stratigraphy,engineering geology and tectonic character etc,so as to identify the geohazards types and lay a foundation for the comprehensive evaluation. At the same time,the concepts of geohazards and geology disaster are explained and the difference is pointed. After concluding the different sorted methods of geohazards,a method which is more compatible to ocean development is brought forward. By the collected information of this area,there are several kinds of geohazards which have potential menace to seabed structures,such as tidal scour trough,shoal,buried paleo channel,shallow gas,liquefaction sand layer and soft layer. From their forming,distribution and potential menace,this thesis carefully analyzes these geohazards factors.Regarding the above geohazards factors as evaluation indicators,and determining their weight values and membership degrees using analytic hierarchy process and normal distribution function,the fuzzy comprehensive evaluation model is established to quantificationally evaluate the geohazards risk of study area. According to the evaluation results,the study area is divided into five risk-level regions. It objectively and authentically reflects the geohazards risk and its distribution features,and proves that the study of this thesis is beneficial for the seabed structures and geological disaster prediction. |
PDF Full Text Request