云南地区构造应力应变场年变化特征的数值模拟

NUMERICAL SIMULATION OF ANNUAL CHANGE CHARACTERISTICS OF TECTONIC STRESS-STRAIN FIELD IN YUNNAN AREA

根据云南地区的地质构造、三维波速结构、地震活动性等相关资料,建立云南地区三维非线性有限元模型,模拟云南地区构造应力应变场的年变化特征。结果表明:1)云南地区的地壳运动速度具有北强南弱、西高东低、围绕东喜马拉雅构造结顺时针旋转的特征;2)由于印度洋板块的俯冲作用,造成云南地区地壳运动速度场的规律性变化:红河断裂带以东由北部的SEE向到南部的SE向,而以西为SE-NS-SW向变化;3)最大主应变具有西高东低,北强南弱的特征,达到10-8量级,主要分布在滇西地区、安宁河断裂带两侧及小江断裂北段;4)最大主应力主要分布在断裂带沿线及其交汇处,最大差应力分布与其较为一致;滇南地区具有较大的差应力分布,且处于拉张状态,而其他地区大部分为压性状态。

On the basis of the geological structure, 3 D velocity structure and seismic activity in the Yunnan area a 3D finite element model is established, for simulating the present-day annual change characteristics of tectonic stress-strain fields in Yunnan area. The results indicate that ： 1 ） The crustal movements in the north and west of the area are stronger than that in the south and east, also the Yunnan area is characterized by clockwise rotation around the eastern Himalayan syntaxis. 2） Because of the subduction of the India plate, the directions of the crustal movement are as follows ： in the east of Red river fault, it＇ s from SEE in the north to SE in the south, while in the west it＇ s SE-NS-SW. 3） The maximum principal strain shows the pattern of higher value in the west and north but lower in the east and south, also the maximum value reaches 10^-s, it＇s mainly on the western Yunnan area, both sides of the Arming river fault and the north segment of Xiaojiang fault. 4） The maximum principal stress are mostly located along the faults zones and their intersections, the distribution of the maximum differential stress accords with it. In addition, in the south of Yunnan area the differential stress is high, and is tensile, while that is mostly compressive in the other place.