金沙江上游快速隆升河段复杂结构岩体灾变特征与机理

Genetic Mechanism and Disasters Features of Complicated Structural Rock Mass Along the Rapidly Uplift Section at the Upstream of Jinsha River

横断山脉北麓金沙江上游河段沟壑纵横,水能资源丰富。中、晚更新世以来,快速隆升的新构造活动导致该河段复杂结构岩体在重力场的持续作用下灾变频繁。笔者阐述了该河段高地应力的基础地质背景与金沙江板块构造结合带蛇绿岩套的复杂结构岩体基本特征,提出了快速隆升河段的基本认知,建议将≥5mm/a作为快速隆升河段的界限值;列举了21.4km河段内不同时期、不同类型4处大规模堵江事件的证据和基本特征,阐述了其与快速隆升之间的关系;运用地质过程机制法分析了4个堵江体的致灾机理,指出早期堵江残体为未来人类工程活动的潜灾体。

Ravines gullies crisscrossed that makes hydropower resources abundant at the up reaches of Jinsha River,north slope of Hengduan Mountain.Since the Middle and the Late Pleistocene,rapidly uplift neotectonic activity gives rise to gravitational deformation and disasters occurrence due to the complexed structural rock mass in this river section.Basic geological background due to high geostress and the basic features of the complicated structural rock mass for ophiolite suite developed in Jinsha River plate tectonics joint belt of this river section were stated.A new concept of rapid uplift river section is put forwarded,annul uplift value up to≥5mm/a is recommended to be the threshold of rapid uplift river section.Evidences and basic features related to four events of huge landslide dams originated from defferent time and different scale were enumerated,the relationship between the rapid uplift riversection and four landslide dams was expressed.Genetic mechanism of four huge landslide dams developed in the reach of 21.4km river section was disccussed and analyzed based on geological process mechanism method,and earlier landslide dam residual might be a potential harzadous for the future human activities is pointed out.