Abstract:

In order to study the distribution of fractures controlled by layer curvature, fold and fault-related folds in East Kuqa, including one anticline (Biyoulebaoguzi Anticline profile), one fault-bent fold (Kezilenuergou Faultbent Fold profile) and one drag fold (Yangxia Coal-mine Drag-fold profile), are selected as investigating profile, and density of their structural factures and the layer curvature of middle-lower Jurassic and Triassic are measured. The result shows that the layer curvature has an effect on the fracture density; structural fractures are easier to be developed in the layers with larger curvature compared with those with smaller one within the same stratum. Besides, there is a positive linear relationship between fracture density and layer curvature. The mechanics of layer curvature’s effect on structural fracture from angle of solid mechanics is discussed: fracture density is tightly related to stress distribution, and stress is proportional to curvature in bent beam model; hence, a positive linear relationship exists between the fracture density and layer curvature, which is applied to both elastic and plastic folds.

Key words: words curvature, structural fracture, Eastern Kuqa, fracture density, mechanical mechanism

摘要：

为了研究地层曲率对构造裂缝发育的控制作用, 以库车东部中?下侏罗统至三叠系碎屑岩地层为例, 选取其中3 个褶皱或与断层相关褶皱(比尤勒包谷孜背斜、克孜勒努尔沟断层转折褶皱和阳霞煤矿牵引褶皱)为测量剖面, 进行构造裂缝面密度测量和地层曲率统计。结果表明: 地层曲率会影响构造裂缝的发育程度, 在同一地层中, 曲率大的位置比曲率小的更容易发育裂缝, 并且裂缝密度与地层曲率之间呈正线性关系。从固体力学角度对地层曲率影响裂缝发育的力学机制进行探讨, 认为裂缝密度与应力分布密切相关, 而应力与曲率呈正比例关系, 因此裂缝密度与地层曲率呈线性关系, 此结论对于弹性和塑形挠曲都成立。

关键词: 曲率, 构造裂缝, 库车东部, 裂缝面密度, 力学机制