锦屏一级水电站左岸深部卸荷裂隙的加固方案及数值模拟研究

STUDY ON REINFORCEMENT TECHNOLOGY OF DEEP UNLOADED FISSURES IN LEFT BANK OF JINPING FIRST STAGE HYDROPOWER STATION AND ITS NUMERICAL SIMULATION

锦屏一级水电站左岸边坡1650～1900m高程的岩体内存在着大量的卸荷裂隙。这些裂隙分布在50～300m深度范围内,数量多,规模大,延展长,走向基本平行于河道。水电站坝顶高程为1885m,正常蓄水位为1880m,大坝上游岩体的深度卸荷裂隙基本上位于正常蓄水位之下,而大坝下游的深度卸荷裂隙又受到水电站泄流导致的雾化雨的影响。这些深部卸荷裂隙在水的长期作用之下,工程性质进一步恶化,对大坝拱肩的安全性具有不利的影响,必须进行加固。采用通常的灌浆、锚索技术不能很好地予以加固。借助于现存的地质探洞,利用锚固洞技术、预应力锚梁技术予以加固可望取得较好的效果。选择左岸雾化区IV–IV剖面,用数值模拟方法,分别对锚固洞方案、预应力锚梁方案进行数值模拟计算。通过比较两种加固方案裂隙周围塑性区的分布状态发现,预应力锚梁技术对卸荷裂隙的加固效果较好。

There are many unloaded fissures in elevation more than 1 650 m in the deep left bank of Jinping First Stage Hydropower Station. These fissures occur in the depth from 50 m to 300 m, with large quantity, large scale and long extension, and strike basically parallel with the waterway. The elevation of the dam crest is 1 885 m, and its normal impounded level is 1 880 m. Therefore, these fissures possess adverse impact on safety of the dam after water impound and must be reinforced. The usual grouting or anchor cable technology can not reinforce it better. By the aid of existing geologic exploratory tunnel, anchor tunnel technology and prestressed anchor beam technology maybe have good reinforcement effects. Anchor tunnel technology is a new kind of technology which makes use of existing geologic exploratory tunnels, lays steel and fills concrete in the tunnels to form reinforced concrete columns in order to prevent side slopes from sliding by tensile strength and shear strength of reinforced concrete. Prestressed anchor beam technology is one that is improved from anchor tunnel technology, which divides the anchor tunnel into key reinforcement section and common reinforcement section. The key reinforcement section is often the position where faults or fissures occur while the common reinforcement section is the position where rock mass is good. IV - IV section in the foggy region of left bank is selected for numerical simulation of anchor tunnel and prestressed anchor beam. After comparison of the reinforcement effect of both technologies, it is found that the reinforcement effect of prestressed anchor beam is better than that of anchor tunnel.