Analysis of the connectivity rate of the gently dipping structural plane of the foundation rock of an arch dam of a hydropower station in southwest China
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摘要:
连通率是岩体内部结构面发育尺寸及贯通程度的重要指标, 决定着岩体的工程力学特性, 对边坡、坝基等工程岩体的整体强度和稳定性评价等发挥着至关重要的作用。以西南地区某水电站拱坝建基典型岩体缓倾结构面为研究对象, 根据现场岩体实测数据, 基于自行开发的裂隙网络模拟程序, 采用蒙特卡洛(Monte-Carlo)随机模拟方法对水电站左、右岸岩体不同剪切方向下缓倾结构面的连通率和岩体强度参数开展研究。研究表明: 该水电站左、右岸岩体在不同剪切方向上的连通率是不同的, 通过不同方向的角度旋转, 总体获得的裂隙连通率较低; 水电站右岸平洞PD02处缓倾角结构面的裂隙连通率约在27.35%左右, 摩擦系数为1.04, 黏聚力为0.89 MPa。研究成果可为水电工程建设提供理论参考和借鉴。
Abstract:The connectivity rate plays an essential role in the stability evaluation of engineering rock masses such as slopes and dam foundations. This paper takes the foundation rock mass of an arch dam of a hydropower station in southwest China as the research object. Based on the field-measured data and the self-developed fissure network simulation program, we used the Monte-Carlo stochastic simulation method to calculate the connectivity rate of the gently dipping structural planes and the strength parameters in different shear directions of rock mass on the left and right bank of the hydropower station. The results show that the connectivity rate of the left and right banks of the hydropower station is different in different shear directions, and the overall fissure connectivity rate is low. The fissure connectivity rate of the gently dipping structural planes at PD02 on the right bank is about 27.35%, the friction coefficient is 1.04, and the cohesion is 0.89 MPa. The research results can provide a theoretical reference for this and similar projects.
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Key words:
- low-angle dip /
- intermittent joint /
- connectivity rate /
- Monte-Carlo
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表 1 PD02缓倾角结构面分组统计表
Table 1. Statistical table of three groups of gently dipping structural planes at PD02
组别 产状 优势方位 裂隙条数 百分比/% 走向/(°) 倾向 倾角/(°) ①NWW组 270°~295° NE为主 10°~30° NWW285°NE∠26° 54 43.90 ②NW组 295°~325° NE为主,少量SW 12°~28° NW306°NE∠21° 25 20.33 ③NE组 18°~75° NW为主 3°~13° NE47°NW∠11° 20 16.26 表 2 缓倾角结构面几何特征参数
Table 2. Geometric characteristic parameters of three groups of gently dipping structural planes
平洞编号 结构面组号 几何特征 概率分布模型 平均值 标准差 PD02 ① 间距/m 负指数分布 2.28 1.86 倾向/(°) 正态分布 9.2 4.97 倾角/(°) 正态分布 29.9 5.60 迹长/m 对数正态分布 1.08 0.88 ② 间距/m 对数正态分布 2.25 2.97 倾向/(°) 正态分布 28.0 9.47 倾角/(°) 正态分布 26.6 5.00 迹长/m 对数正态分布 1.01 0.67 ③ 间距/m 对数正态分布 10.99 6.50 倾向/(°) 正态分布 352.4 4.38 倾角/(°) 正态分布 27.6 5.64 迹长/m 对数正态分布 1.04 0.58 表 3 PD02缓倾角结构面网络模拟结果
Table 3. Network simulation results of the gently dipping structural planes at PD02
旋转角度/(°) 连通率/% 摩擦系数 内聚力/MPa 旋转角度/(°) 连通率/% 摩擦系数 内聚力/MPa 0 0 1.2 1.2 90 17.88 1.09 0.99 10 0 1.2 1.2 100 0 1.2 1.2 20 0 1.2 1.2 110 0 1.2 1.2 30 0 1.2 1.2 120 0 1.2 1.2 40 0 1.2 1.2 130 0 1.2 1.2 50 0 1.2 1.2 140 0 1.2 1.2 60 6.20 1.16 1.13 150 0 1.2 1.2 70 40.15 0.96 0.74 160 0 1.2 1.2 80 45.17 0.93 0.68 170 0 1.2 1.2 缓倾方向平均值 连通率/% 27.35 摩擦系数1.04 内聚力/MPa 0.89 -
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