小湾水电站进水口高边坡变形机理分析及工程意义

小湾水电站进水口高边坡地质条件及开挖坡型复杂，断层、节理裂隙发育并相互切割，坝顶平台至进水口底板平台平均开挖坡度88°，最大高差106m，其中垂直开挖段81m，最大水平退坡深度170余米。伴随边坡开挖过程中，边坡上部岩体产生了一系列的变形破裂现象，主要表现为沿混凝土坡面分布的张开宽度和延伸长度不一的裂缝及起壳现象。本文结合边坡的实际工程地质条件和监测结果数据，对变形破裂现象的形成机制进行了系统的分析。结果表明，裂缝产生的原因主要是由于地处高地应力区岩体在边坡开挖过程中产生的卸荷回弹表现，是正常的卸荷松弛变形。在此基础上，对边坡的稳定性分析表明，该边坡稳定性良好。

DEFORMATION-FRACTURE MECHANISM ANALYSIS AND STABILITY EVALUATION OF HIGH SLOPE FOR WATER-INTAKE OF XIAOWAN HYDROPOWER STATION

The geological condition and excavation shape of a high rock slope at the water-intake of a hydropower station are very complex. The faults, joints and fissures develop well in the rock mass and cut each other, which makes the engineering geological property for the rock mass to degenerate. The average excavation inclination is 88° and the maximal height difference is 106 m including vertical height part  of 81 m from the dam crest to the bottom of the water-intake.  The maximal horizontal depth of excavation is about 170 m. During the slope excavation, a series of deformation and fracture phenomena appear along the concrete surface covering the slope. They mainly includes cracks and surface bulging.  Combining the engineering geological conditions and the monitoring data of the scene, a systematic analysis is made on the mechanism of deformation and fracture. The results indicate that the unloading fracture zone of the high rock slope especially in a high-intensive geo-stress environment is very significant in rock slope engineering. So, the fracture system is the normal response of the unloading and relaxation. Base on the analysis, the assessment is made on the slope stability. The analytical results show that the slope is stable at present.