不同组合形式叠瓦状逆断层地应力分布规律研究

发布时间：2018-07-25 10:39

【摘要】：叠瓦状逆断层是地壳中分布的主要断层组合形式之一。为了揭示地质演化过程中不同组合形式下叠瓦状逆断层间地应力分布规律,采用大型物理模拟手段,以龙门山地区的地质构造为背景,研究了两条平行叠瓦状逆断层和在其间与之相交的断层组合形式下地应力分布和变化规律。取得的主要认识如下:(1)对于研究区仅分布两条平行的叠瓦状逆断层,构造挤压方向与它们的走向垂直的情况,靠近构造挤压端的断层会首先发生失稳破坏,较大的局部应力释放会使地壳内部整体应力有所降低,但在下伏断层的深部会出现应力的突然升高;(2)对于研究区不仅分布两条平行的叠瓦状逆断层,而且在两条断裂之间存在一条与它们垂直的逆断层,构造挤压方向与叠瓦状逆断层垂直,叠瓦状逆断层附近浅层地应力变化较早,地壳易沿叠瓦状逆断层首先失稳活动,进而带动所夹逆断层的地应力发生调整;(3)对于研究区不仅分布两条平行的叠瓦状逆断层,在其间夹着走向与它们垂直的逆断层,构造挤压方向与叠瓦状逆断层斜交情况,地壳易沿所夹断层首先失稳活动,进而触发叠瓦状逆断层地应力变化;(4)仅存在叠瓦状逆断层,地应力分布较为均匀;叠瓦状逆断层间夹逆断层的情况下,在断层端部和几条断层交汇部位出现了应力集中现象。该问题的研究对区域稳定性评价和地震预测具有一定的指导意义。
[Abstract]:Imbricate thrust fault is one of the main fault assemblages distributed in the crust. In order to reveal the distribution of in-situ stress between imbricate thrust faults in different combination forms during geological evolution, a large-scale physical simulation method is adopted, and the geological structure in Longmen Mountain area is taken as the background. The distribution and variation of in-situ stress of two parallel imbricate thrust faults and their intersecting fault assemblages are studied. The main results are as follows: (1) for only two parallel imbricate thrust faults distributed in the study area, if the direction of tectonic compression is perpendicular to their strike, the failure of faults near the compressive end of the structure will occur first. The larger local stress release will decrease the overall stress in the crust, but it will suddenly increase in the deep part of the underlying fault. (2) not only two parallel imbricate reverse faults are distributed in the study area, Moreover, there is a thrust fault perpendicular to them between the two faults, the direction of tectonic compression is perpendicular to the imbricate thrust fault, the shallow ground stress changes earlier near the imbricate thrust fault, and the crust is prone to be unstable first along the imbricate thrust fault. Then the in-situ stress of the thrust fault is adjusted. (3) for the study area, not only two parallel imbricate thrust faults are distributed, but also the thrust faults with strike perpendicular to them, the tectonic compression direction and the imbricate thrust fault are oblique. The earth's crust is easily unstable along the fault, and then triggers the change of in-situ stress of the imbricate thrust fault. (4) there is only the imbricate thrust fault, and the distribution of the in-situ stress is more uniform. In the case of interlocking thrust fault between the imbricate thrust faults, Stress concentration occurs at the end of the fault and at the intersection of several faults. The study of this problem has certain guiding significance for regional stability evaluation and earthquake prediction.
【作者单位】：长安大学地质工程与测绘学院;国土资源部岩土工程开放研究实验室;西北有色勘测工程公司;
【基金】：中央高校基本科研业务费专项资金(310826151048) 国家自然科学基金(41030749,41072223) 中国地质调查局项目(1212010914205)资助
【分类号】：P315

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