大型复杂岩质高边坡安全监测与分析

SAFETY MONITORING AND STABILITY ANALYSIS OF LARGE-SCALE AND COMPLICATED HIGH ROCK SLOPE

岩石高边坡稳定性是水电站建设能否顺利进行的关键问题之一。锦屏一级水电站左岸开挖高边坡地应力高、断层裂隙发育、岩体卸荷深度大,地质条件十分复杂,边坡在施工期和运行期的稳定性问题特别突出。介绍左岸边坡的监测布置,并对岩体表面变形趋势、空间分布形态、变形与开挖的关系进行分析,对多点位移计变形大小、岩体变形与结构面的关系进行探讨,对平洞石墨杆收敛计变形、谷幅平距观测、锚索荷载和抗剪洞变形等监测结果进行综合分析,得到边坡岩体的变形规律。研究结果表明,锦屏一级水电站左岸边坡岩体受开挖影响的范围较大,超过80m,边坡岩体卸荷松弛变形量级较大,边坡岩体应力释放与转移过程较长,边坡达到完全稳定需要的时间较长。该工程的监测成果可供其他类似工程参考和借鉴。

The stability of high rock slope is one of important issues during construction period of a hydropower station, which is related to success of project. The stability of the left bank excavation slope of Jinping first stage hydropower station is remarkable because of its high ground stress, faults and fissures developed, large-scale excavation, deep unloading and complicated geological conditions. The layout of safety monitoring of the left bank excavation slope is introduced： the deformation trend, spatial distribution and the relationship between deformation and excavation of surface deformation points are investigated. The deformation size and the relationship between deformation and structural face of multi-point extensometers are discussed. The deformation laws of rock mass of the left bank slope are obtained based on the comprehensive analysis of the monitoring results of surface deformation points, multi-point extensometers, graphite bar-type extensometers, measurement of valley width, anchor cable dynamometers and shearing-resistance tunnels. The research result shows that the influence scope of excavation in left bank slope is larger than 80 m; and the magnitude of relaxation deformation of the left bank slope is relatively large. The process of transfer and release of slope rock mass is long and the longer time is needed for the slope to reach complete stability. The monitoring results can be used for reference by other similar engineering.