双核型旋扭构造影象云纹法实验分析

EXPERIMENTAL ANALYSIS BY SHADOW MOIRE METHOD FOR BINUCLEUS-TYPE TORSIONAL STRUCTURE

本文采用近年引入的影象云纹法,对作者提出的双核型旋扭构造进行了大变形实验分析。实验结果表明,双核型旋扭构造展布区域发育两个凹陷与两个隆起,前者与平均应力引张区相对应,后者与平均应力挤压区相一致。沿凹陷轴线发展起来的简单S形构造可进一步发展成“对帚状S形构造”。文中还给出了挠度W与S形凹陷轴线和双核连线的夹角θ,以及区域地块旋转角度β相互关系的实验曲线。

The binucleus-type torsional structure presented by the authors is a new type of structure . It is characterized by its two nuclear columns ,which differ from that of uninucleus - type torsional structure . A shadow moire method is applied to experimental analysis for the new structural type of large deformation . The result of experiments shows that two depressions and two upwarps are developed in the area where a binucleus-type torsional structure is developed . The depression districts happen to correspond to the extensive districts of mean stress and the upwarp districts to those compressive ones . Extensive faults are developed along the axes of depressions with progressive loading . The rate of depression is greater than that of upwarp before faulting . The faults spread progressively with time and form a sigmoid structure . Furthermore , it can be developed to form an asymmetrical - broom sigmoid structure . Some experimental curves are given in the paper to show the relations among the deflection (W), the angle (θ ) between the axis of the sigmoid depression and the line linking the two nuclear columns , and the rotational angle (β ) of the regional massif. These curves may be available for the prediction of sedimentary deposits and research on geological structures .