Field model tests and bearing capacity analysis of tunnel anchorage of Jindong Bridge
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摘要: 金东大桥隧道锚建在复杂岩体地层中,尚无类似的工程经验借鉴,为分析该桥隧道锚承载能力,在实体锚上游侧山体边坡开挖模型试验洞,制作相似比1∶11的隧道锚模型,采用后推法进行模型试验,包括弹塑性阶段试验、蠕变试验和满负荷的超载试验,配套进行了岩体（石）物理力学性质试验、岩体声波测试。分析结果表明：模型锚岩体性状与实体锚基本接近,模型锚围岩声波低于实体锚,模型锚地层具有较好的地质代表性；模型锚至少在8倍设计荷载作用下变形处于近似弹性阶段,在6倍设计荷载长期作用下未出现蠕变现象,推断实体锚围岩的超载稳定系数>8,长期安全稳定系数>6,成果可为类似复杂围岩的工程设计提供参考。Abstract: Tunnel anchorage of Jindong Bridge is built in the complicated rock stratum, but there is no similar engineering experience for reference. In order to analyze the bearing capacity of tunnel anchorage of Jindong Bridge, a model test tunnel is excavated on the side slope of the mountain at the upstream side of the real anchorage to make a tunnel anchorage model of 1∶11; then, the backstepping method is adopted to conduct the model tests, including elastic-plastic stage tests, creep tests and full-load overload tests, as well as the supporting tests such as physical mechanical property tests on rock mass (rock block) and acoustic wave tests on rock mass. The test results show that the character of the model anchorage rock mass is basically the same as that of the real anchorage, the acoustic wave of the surrounding rock of the model anchorage is lower than that of the real anchorage, and the stratum of the model anchorage has a better geological representation. The model anchorage exhibits the approximate elastic deformation under the action of 8 times the design load, and there is no creep under the long-term action of 6 times the design load. It is deduced that the surrounding rock of the real tunnel anchorage has the overload stability coefficient of more than 8 and the long-term safety stability coefficient of more than 6. The results can be used as the reference for the engineering design of similar complicated surrounding rock.
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Keywords:
- Jindong Bridge /
- tunnel anchorage /
- field model test /
- bearing capacity
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图 1 岩体波速分段统计直方图
Figure 1. Statistical histogram for subsection of wave velocity of rock mass
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图 4 锚体与围岩前表面测点布置图
Figure 4. Arrangement of measuring points on front surface of anchorage and surrounding rock
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图 5 锚体与围岩内外测点布置图
Figure 5. Arrangement of internal and external measuring points of anchorage and surrounding rock
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图 8 1p~24.59p荷载试验锚体应变曲线
Figure 8. Anchorage load-strain curves of loading tests under 1p~24.59p
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图 9 1p~8p荷载试验测线变形曲线
Figure 9. Deformation curves at measuring points of loading tests under 1p~8p
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图 10 1p和3p荷载试验典型测点荷载-变形曲线
Figure 10. Load-strain curves at typical measuring points of loading tests under 1p and 3p
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图 11 5p和8p荷载试验典型测点荷载-变形曲线
Figure 11. Load-strain curves at typical measuring points of loading tests under 5p and 8p
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图 12 锚体与围岩前表面及内部测点变形-时间曲线
Figure 12. Strain-time curves at measuring points of anchorage and surrounding rock
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图 13 锚体内部测点应变-时间曲线
Figure 13. Strain-time curves at internal measuring points of anchorage
表 1 锚碇围岩岩性及主要物理力学参数
Table 1 Lithology and primary physical and mechanical parameters of surrounding rock of anchorage
洞别 岩性名称 天然块体密度/(g·cm-3) 含水率/% 孔隙率/% 饱和单轴抗压强度/MPa 软化系数 泊松比 抗拉强度/MPa 岩体变形模量/ GPa 混凝土与岩体抗剪强度f, C/MPa 抗剪断 抗剪(摩擦) 实体锚左锚洞 粉砂质白云岩夹黑云母石英片岩 2.64~2.93 0.10~0.30 0.69~3.86 19.9~81.0 0.35~0.90 0.26~0.29 2.79~5.01 2.13~2.51 1.50, 1.28 1.15, 0.62 2.74 0.17 1.90 56.1 0.68 0.25 4.10 2.35 实体锚右锚洞 石英白云母片岩、含碳白云母石英片岩 2.73~2.82 0.70~0.85 3.98~4.11 16.8~21.0 0.73~0.83 0.20~0.25 1.49~2.11 — 0.49, 0.91 0.47, 0.47 2.77 0.77 4.04 18.7 0.76 0.23 1.81 方解石黑云母变质细砂岩 2.72~2.77 0.14~0.19 1.14~1.71 52.2~53.3 0.64~0.81 0.22~0.26 3.44~4.60 0.74~159 1.20, 1.36 1.08, 0.58 2.73 0.16 1.43 52.9 0.71 0.24 3.99 1.16 模型洞 含榴黑云角闪斜长片麻岩 2.63~2.76 0.09~0.78 0.91~6.11 29.8~58.5 0.44~0.87 0.21~0.26 3.55~4.83 — — — 2.71 0.44 3.06 42.1 0.73 0.25 4.15 注： 表中横线上数值为范围值,横线下数值为平均值。
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表 2 1p~24.59p荷载试验模型锚与围岩测点变形最大值
Table 2 Maximum deformations of anchorage and surrounding rock at measuring points of loading tests under 1p~8p
荷载级别 测线 左侧测孔（测点） 左锚 中隔墙 右锚 右侧测孔（测点） K11 K9 K7 K5 K3 K1 ZM K0 YM K2 K4 K6 K8 K10 K12 1p L0 7 7 18 11 20.5 29 53.5 36 49 21.5 18 14 10 8 6 L1 14.5 17.5 21 48 37 48 19 16.5 9 L3 17 18 38 36.5 38 17 12 L5 13 17 37 34 30 18.5 9 3p L0 1 12 30 41 61 106 141 143 136 83 64 30 20 6 0 L1 22 36 52 144 145 142.5 55.5 43 8 L3 25 48 188 136 173 56 37 L5 14.5 33 195 119 191 54.5 24 5p L0 33 53 100 119 177 260 342.5 352 337 236 188.5 106 76 42 24 L1 89 115 144 352 352 358 185 131 48 L3 80 86 129 408 336.5 410 168 121 29 L5 65 116 436 342 439 145 79 8p L0 56 109 201 265 385 585 730 719 699 499 389 230 157 59 33 L1 159 228 295 750 744 737 392 263 91 L3 157 175 272 831 718 826 352 264 20 L5 121 228 871 717 881 286 159 24.59 p L0~ L5 845 1303 1980 4030 4770 5209 4940 5230 3790 3790 1860 830 442
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表 3 1p~8p荷载试验锚体与围岩测点变形残余量
Table 3 Residual deformations point of anchorage and surrounding rock at measuring points of loading tests under 1p~8p
(μm) 荷载 K3-1 K3-2 K3-3 K3-4 K1 ZM1 ZM2 ZM3 ZM4 K0-1 K0-2 K0-3 K0-4 YM1 YM2 YM3 YM4 K2 K4-1 K4-2 K4-3 K4-4 1p 20.5 13 14 14 19 31.5 31 23 32 19 27 31.5 23 39 34 32 23 17.5 16 18 12 15.5 3p 5 9 2 4 9 10 9 20 10 16 5 5 6 10 5.5 8 6 5 11 0.5 0 5 5p 9 5 2 2 10 12.5 22 21 20 19 13 17 19 15 21 21 19 17 0.5 12 2 18 8p 26 1 0 0 44 33 40 41 35 34 30 36 46 28 42 35 36 27 20 1 0 1
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表 4 1p~8p荷载试验位错计及测缝计测点最大值及残余量
Table 4 Maximum values and residual volumes at measuring points by dislocation meter and jointmeter of loading tests undr 1p~8p
(μm) 荷载级别测点编号 1p 3p 5p 8p WC3 WC7 CF2 CF3 WC3 WC7 CF2 CF3 WC3 WC7 CF2 CF3 WC3 WC7 CF2 CF3 最大值 3.95 0 0 5.6 17.25 3.45 1.68 2.8 14.22 4.62 2.25 11.25 18.96 2.31 1.68 14 残余量 1.58 0 0 5.6 5.75 0 1.68 1.12 0 2.31 2.25 7.25 6.3 2.31 1.68 0
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