Stress-deformation behavior of a blast-fill dam
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摘要: 结合实测数据与数值模拟方法对某定向爆破堆石坝体结构在不同阶段的应力变形特性进行了分析,探讨定向爆破堆石坝的应力变形规律,并重点讨论了爆破堆石体和防渗结构的力学行为。对比分析表明:不同于常规坝体的最大沉降位于坝体2/3部位,爆破堆石最大沉降发生在爆破堆石体顶部,爆破堆石及坡积物的可压缩性是其产生较大沉降的主要原因。在此基础上,分析了爆破堆石体沉降对防渗结构应力变形的影响。结果表明:由于筑坝材料组成复杂、力学特性相差较大,导致大坝局部出现一定的不均匀沉降。700 m平台以下的反弧处出现较大的变形和应力,对沥青混凝土防渗斜墙变形造成较大影响。此外,库水位的抬升使沥青混凝土斜墙的应力和变形规律发生了较大变化,防渗体应力和变形明显增加。研究得出的定向爆破堆石坝的应力变形规律,较为全面、真实地反映了定向爆破堆石坝的爆破堆石体、坝体及防渗体的运行性态,同时也对高面板堆石坝、软岩筑坝、弃渣坝、滑坡及堰塞体等大变形结构体的安全性态研究具有一定的参考价值。Abstract: The stress-deformation behaviour of a blast-fill dam at different stages was examined based on in-situ monitoring data and finite element analysis (FEA). The mechanical behaviour and the impervious structures of blasting rockfill were investigated. Comparative analysis showed that the maximum settlement of the blasting rock occurred at the top of the blasting rockfill. Different from the conventional dam, the maximum settlement is located at 2/3 of the dam. The compressibility of the blasting rockfills and the slope deposit were the main factor for their large settlement. The numerical simulation was used to analyse the influence of stress-deformation behaviour of impervious structures. The results showed that due to the complex composition of the dam material and the large difference in the mechanical properties of the material, some uneven settlement of the dam occurred locally. Large deformation and stress occurred at the reverse arc below the 700.00 m platform, which was a greater impact on the deformation of the asphalt concrete wall. The rise of the water level caused a great change in the stress-deformation behaviour of the asphalt concrete wall, and the stress-deformation of the impermeable body increased significantly. The above summary is a comprehensive and true reflection of the operational behaviour of the blasting rockfill body, dam body and impervious structures of the blast-fill dam. The findings of this study are of great value for the study of the safety state of high face rock-fill dam, soft rock dam, slag field, landslide and quake lake.
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Key words:
- blast-fill dams /
- safety monitoring /
- stress-deformation behavior /
- impervious body
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表 1 坝体材料的物理力学特性参数
Table 1. Parameters of calculation model
材料 K ${R_{\rm{f}}}$ $n$ ${K_{\rm{b}}}$ $m$ ${K_{{\rm{ur}}}}$ ${n_{{\rm{ur}}}}$ $\varphi $ $c$ /kPa$\rho $ /(g·cm−3)人工堆石料 500 0.72 0.25 250 0 1 000 0.12 44 0 2.12 爆破堆石料 700 0.79 0.30 350 0 1 300 0.10 46 0 2.19 坡积料 104 0.70 0.60 64 0.40 210 0.30 36 0 1.78 冲积料 450 0.81 0.40 250 0.30 900 0.20 45 0 1.89 沥青混凝土 317 0.47 0.33 200 0.25 600 0.20 32 0 2.45 表 2 爆破完成后典型断面爆破堆石体应力、变形计算值
Table 2. Stresses and deformations of blasting rockfills with typical sections after blasting
典型横断面 最大水平位移/m 竖直位移/m 最大主应力/MPa 最小主应力/MPa 应力水平 顺流向 逆流向 0+150 0.22 0.28 0.63 0.76 0.28 0.35 0+200 0.21 0.31 0.78 0.90 0.31 0.31 0+250 0.19 0.11 0.60 0.83 0.18 0.19 表 3 爆破堆石体不同区域内压缩层厚度及平均压缩模量统计
Table 3. Statistic of compression layer thickness and average compression modulus for blasting rockfill
测点 总沉降量/mm 爆破堆石体厚/m 坡积物厚/m 压缩层厚度/m 压缩模量/MPa 范围 均值 范围 均值 范围 均值 范围 均值 范围 均值 总平均值 Ⅰ 314~696 509 11.5~33.0 19.7 7.0~26.5 17.6 25.5~43.5 38.2 11.4~53.3 34.8 91.8 Ⅱ 175~410 269 23.0~45.0 33.8 2.0~21.5 13.1 27.0~60.0 48.3 43.5~132.7 96.0 Ⅲ 95~484 291 22.5~43.5 36.7 15.0~23.5 20.9 45.5~66.0 57.6 73.9~227.7 144.6 注:测点Ⅰ、Ⅱ、Ⅲ测点分别位于上游685~695 m高程附近、坝轴线附近及下游685~695 m高程附近。 表 4 不同工况下典型断面应力、位移计算值
Table 4. Stresses and deformations of blast-fill dam with typical sections
工况 典型横断面 最大水平位移/m 竖直位移/m 最大主应力/MPa 最小主应力/MPa 应力水平 顺流向 逆流向 竣工期 0+150 0.40 0.25 0.93 1.22 0.48 0.40 0+200 0.37 0.41 1.17 1.26 0.50 0.48 0+250 0.39 0.23 0.71 1.38 0.23 0.43 蓄水期 0+150 0.40 0.25 0.94 1.27 0.50 0.40 0+200 0.42 0.39 1.19 1.27 0.48 0.49 0+250 0.41 0.21 0.72 1.39 0.45 0.42 表 5 不同水位下沥青混凝土斜墙应力、位移计算值
Table 5. Stresses and deformations of asphalt concrete wall under different water levels
计算
水位/m水平位移
极值/m竖直位移
极值/m最大
主应力/MPa最小
主应力/MPa700.00 0.101 0.406 0.36 0.16 720.00 0.482 0.830 1.11 0.65 731.00 0.677 1.050 1.93 1.27 -
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