摘要
基于城市隐伏活断层钻孔联合剖面探测的多次实践,总结出一种优化的断层定位方法——对折法。其步骤为:首先实施剖面两端的钻孔,在确保断层在两孔间之后,在两孔中间位置布设第3孔;继续确定断层所在区段,然后在其间二分之一处布设下一钻孔,依次类推,逐渐限定出断层的准确位置。同时,引入孔间标志层位坡降这一量化指标替代落差分析,并归纳出2个判据:1)若两孔间主要标志层位坡降>0,且坡降由浅至深递增,表明断层位于两孔之间;2)两孔间实施第3孔之后,若两孔间标志层位坡降相对之前及相邻区段显著增大,且随埋深递增,则为断层所在区段,而正常层位区段孔间标志层位坡降显著减小。应用实例表明,这种方法可较好地实现隐伏活断层的准确定位。
In this paper,an optimized drilling exploration method,the doubling section method,was summarized after many composite drilling section explorations of buried active fault in urban areas.Operation steps of this method are as follows： Firstly,drill a borehole at each of the two ends of the drilling section to make sure that fault is between the two boreholes,then,drill the third borehole at the middle of the two holes;and secondly,confirm again the segment where the fault is and drill the next borehole in the middle of it.By repeating the similar practice,the accurate location of fault can be constrained progressively.Meanwhile,this paper also uses a quantitative indicator,the key horizon gradient between two boreholes,instead of stratigraphic throw,to determine the location of buried fault and puts forward two criterions： 1）the fault is located between two boreholes if the key horizon gradients between these two boreholes are positive and increase with depth;and 2）the fault is located where the key horizon gradients between two boreholes increase obviously relative to the previous values and that of adjacent segments,besides the increase with depth.While in contrast,the key horizon gradient in a normal fault segment decreases obviously.Application cases show that the method can determine precisely the location of buried active fault.
出处
《地震地质》
EI
CSCD
北大核心
2011年第1期45-55,共11页
Seismology and Geology
基金
国家财政部经常性项目(1521044025)
地震行业科研专项(201008003)
关键词
隐伏活断层
钻孔联合剖面
对折法
层位坡降
buried active fault
composite drilling section
doubling section method
key horizon gradient
