摘要:
回顾了城市活断层探测现状，指出了采用二维地震探测在活断层精确定位中存在中浅层小构造控制程度较差，在地层倾角较大地区断层归位不够准确，受建筑物和其它障碍物限制致使测线布设与断层走向斜交造成断层定位不准，以及由于测网密度限制造成的断层交汇处、断层分段点、端点位置控制程度较差等主要问题．从理论上分析了三维地震勘探的优势，认为三维地震勘探可以较好地解决由于二维地震勘探本身的技术缺陷和地表环境、地质条件影响所造成的断层定位不准的问题．通过实例剖析，从野外采集难点, 仪器选择, 观测系统定义, 优化施工设计, 野外质量监控, 特殊数据处理手段, 以及取得的良好地质效果等方面进行详细阐述，论证了利用三维地震探测在城市进行活断层精确定位中的可行性及其意义．
Abstract:
Present state of urban active fault survey is reviewed. Some problems of unban active fault fine locating by using 2D seismic exploration are presented, such as poor controlling of small-scale structures in middle-shallow strata, insufficient precision of fault homing in steeply dipping strata, inaccurate fault location coming from oblique intersection between surveying lines and fault strike due to existing buildings and other obstacles, and inadequate constrain on fault breakpoint, intersection position and endpoint due to sparse surveying grids. Advantage of 3D seismic exploration is analyzed theoretically. The problem of inaccurate fault location, induced by limitation of 2D seismic exploration, surface environment and geological conditions, can be solved by using 3D exploration. The feasibility and significance of using 3D seismic exploration in urban region is demonstrated through example analysis in data acquisition, instrument selection, geometry design, optimizing design, field quality monitoring, special data processing and good geological effects.
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