| In this paper, the Bohai Strait Sea-crossing Tunnel Project area is selected as the study area Through using the fuzzy mathematical evaluation method, this paper focuses on the research the regional crustal stability in the Bohai Strait Sea-crossing Tunnel Project area. The indexes to evaluate the crustal stability of the study area in this paper are fault activity, seismic activity, ground deformation characteristics, stress characteristics and ground geophysical field characteristics. And the weight of each evaluation factor is determined by Analytic Hierarchy Process. In the evaluation, the stability of the crustal is divided into four levels:very stable, stable, unstable, extremely unstable. The study on fault activity and seismic activity shows that the study area is under the control of NNE and NW-trending faults, and most of the faults have had activities since the Late Pleistocene. The study also shows that the seismic is active in the study area and there is a high probability that large earthquakes would happen in the future hundred years in the study area.Moreover, crustal deformation, geophysical field and crustal stress data manifest a trend that these characteristics change along NNE and NW directions, this trend may also be because the impact by NNE and N W trending faults.After the evaluation with the above indexes, the result shows that most of the area is in unstable and extremely unstable state, this situation is mainly caused by the relatively active faults and seismic activity in this area. This evaluation result indicates that it is unfavorable for the planning and construction of the Bohai Strait Tunnel. It is necessary to strengthen the study of faults and seismic in the study area, and pay more attentions to both prevention and treatment of these two adverse factors in the future construction process. |
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