金沙江某水电站地质构造及其对下游坝址的工程影响

Geological structure of the hydropower station at Jinsha river and the influences on the downstream dam site

某水电站工程场地位于金沙江中游河段内,属于高山峡谷地貌。坝址区前期受印支运动期NE向构造应力作用,后期又逐渐转向为NNE向。坝址区发育有其宗向斜褶皱构造,轴向延NW-SE向展布,由于枢纽方位与坝址区河谷方向近重合,其宗向斜控制了坝址区的岩层产状、地质构造展布。主要构造应力场的三向应力状态由"潜在逆断型"转变为"潜在走滑型"。地质构造的复杂,成为影响坝址选择及枢纽布置格局的关键因素。同时,对坝址区地质构造的研究,也为坝型设计的合理优化,提供了可靠的科学依据。

A hydropower station located on the middle reaches of Jinsha river. The topography belongs to alpine valley. In prophase of dam area endured with NE strike tectonic stress on Indosinian movement epoch, then gradually turned to NNE during anaphase. Dam area developped Qizong synclinal fold structure, axial direction spread NW to SE .For the direction of valley on dam area was approximately coincided with hinge of syncline, Qizong syncline controlled with rock attitude and spread of geological structure on dam site. Triaxial stress state turned ＂potential thrust type＂ to ＂potential strike-slip type＂ on main tectonic stress field. The geological structure was complicated which became a critical factor of influence on dam site selection and junction lay pattern. At the same time, the geological structure research on dam site also offered reasonable optimization of dam pattern.and give some sound scientifical evidences.