溪洛渡库区星光三组岸坡倾倒变形成因机制分析

Formation mechanism of Xingguangsanzu toppling deformation in Xiluodu Reservoir

溪洛渡库区星光三组岸坡发生了严重的倾倒变形破坏,由原本的顺层斜坡变为反倾边坡,像星光三组这类特殊的倾倒变形体由于其成因机制与常规的倾倒变形体不同而受到了许多学者的关注。详细描述了星光三组变形体的工程地质条件、变形破坏特征,并基于数值模拟对该倾倒变形体的成因机制进行了分析。结果表明:星光三组岸坡岩层呈现软硬互层的薄层结构,该结构为倾倒变形的形成提供了物质基础;构造作用与金沙江的快速下切分别为变形体的形成提供了高水平地应力与地形条件;溪洛渡库区星光三组岸直倾倒变形演化过程可划分为卸荷变形、时效变形、灾变失稳3个阶段。

The bank slope of the Xingguangsanzu in the Xiluodu Reservoir underwent severe toppling deformation,changed from the original inclined steep-dip bedding slope to the counter-tilt layered slope.Special toppling deformations such as Xingguangsanzu have attracted attention from many scholars because its formation mechanisms are different from the conventional toppling deformations.In this paper,the engineering geological conditions,deformation and failure characteristics of the Xingguangsanzu toppling deformation body are described in detail,and the formation mechanism of the toppling deformation body is analyzed based on numerical simulation.The results show that the thin layer structure of the Xingguangsanzu bank slope are soft-hard interbedded rock slopes,which provides the material basis for the toppling deformation;while the tectonic compression and the rapid incising of the Jinsha River provide high horizontal geo-stress and terrain conditions for the toppling deformation;the deformation evolution process of the Xingguangsanzu bank slope can be divided into three stages,unloading deformation stage,time-dependent deformation stage and destruction and unstability stage.