兰州-天水地区现今区域构造应力场光弹模拟实验研究

STUDYING THE FIELD OF THE TECTONIC STRESS IN LANZHOU-TIANSHUI REGION BY MEANS OF PHOTOELASTIC SIMULATION

摘要:

兰州-天水地区现今区域构造应力场光弹模拟来验的范围是:北纬34°-38°、东经102°-108°之间。我们采用平面模型单轴压缩进行实验。结果表明最大剪应力集中区很有规律地分布在北北东和北西西共轭剪切断裂的端点、弧形拐弯及断裂交汇等部位。与本区强震发生的部位相吻合。同时实验得出的主压应力方向与本区震源机制解很接近。此外通过对同一构造模型施加不同方向载荷及打孔等一系列实验证明:能量的积累,调整和迁移与作用力的方式密切相关,並严格地受着区域应力场的控制。

Abstract:

The field of the tectonioc stress in Lanzhou-Tianshui region was studied by means of photoelastic simulation.Results show that the points where maximal shear stress concentrates are distribfited along NNE and NWW conjugate shear lines and agree very well with the epicentral locations of some historically strong earthquakes.The orien-tations of the principal stress in the present region tally with the mechanism solutions of earthquake foci.
By loading in different directions and punching on the structure mod-el,it is proved that the accumulatioh,adjustment and movement of en-ergy have close relation to the action manners of forces and are strictly controlled by the field of regional stress.In the particular tec-tonic places distributed along the conjugate shear directions of the re-gional stress field,strong earthquakes,will most likely develop and oc-cur.This will provide some useful data for forecasting strong earthqu-akes.