杨房沟坝址高边坡工程地质特征及稳定性评价

Engineering geological characteristics and stability evaluation of the high slope at the dam site of Yangfanggou hydropower station

为掌握杨房沟坝址高边坡稳定性情况及治理措施,采用现场调查及室内分析计算方法对河谷高边坡岩体工程地质特征及稳定性展开了全面研究。得出以下结论:高边坡花岗闪长岩可划分为块状、次块状及镶嵌结构等类型;边坡岩体质量从坡面向内分别为Ⅲ2、Ⅲ1、Ⅱ类,Ⅳ类岩体很少;天然边坡存在松动张裂、楔形体滑动及崩塌等破坏形式,控制性结构面为顺河向卸荷裂隙;从河谷演化角度通过数值模拟方法分析现今边坡应力分布、塑性区范围、变形规律及总体稳定性,认为坝址区天然边坡整体稳定性较好,降雨或地震等不利条件边坡可能存在浅部块体滑移失稳。

In order to evaluate the slope stability and propose control measures for Yangfanggou dam,on-site investigation and laboratory analysis and calculation were used to study the high slope engineering geological characteristics and stability of Yangfanggou dam.It concluded that granodiorite in the high slope exists in block,sub-block,or mosaic structures.Rock mass of the high slope,from the surface to inside,basically could be classified as Class Ⅲ2、Class Ⅲ1、and ClassⅡ,but rare in Class Ⅳ.The slope in natural conditions would be loosened and fractured by tension and take place wedge sliding or collapse.The structural control surface was the unloaded fissures along the river.From the view of valley evolution,a numerical simulation analysis was conducted to calculate the current stress distribution,plastic deformation zone and the overall stability of the slope.The results showed that the natural stability of the slope was good,but its superficial part was prone to slide when raining or earth quaking.