In-situ Experimental Study on Bearing Characteristics of Deep-Buried Tunnel Anchorage in Fractured Rock Mass
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摘要: 为了研究破碎岩体深埋隧洞锚承载特性，以泸定大渡河特大桥为工程背景，根据原位试验获得的混凝土与岩体接触面峰值抗剪强度参数计算锚塞体抗拔安全系数；介绍了1∶10现场原型缩尺试验成果，研究了模型锚极限荷载和强度特性；最后对隧洞锚稳定性作出了整体评价，并提出了工程施工建议.研究结果表明：锚塞体抗拔安全系数为3.48，满足规范规定的稳定性要求；模型锚极限荷载为7.80P （P为设计荷载），模型锚碇系统屈服载荷的特征点为5.25P.Abstract: In order to study the bearing characteristics of the deep-buried tunnel anchorage in the fractured rock mass, and in the engineering background of Luding Dadu river Bridge, according to the peak shear strength parameters of the contact surface between concrete and rock mass obtained by in-situ test, the safety factor of the anchor plug was obtained. The in-situ test results of the 1∶10 scale model anchor were introduced, and the ultimate load and strength characteristics of the model anchor were studied. Finally, the overall stability of the tunnel anchor was evaluated, and the construction proposal was put forward. The results show that the safety factor of the anchor plug is 3.48, which meets the stability requirements of the specification. The model anchor has a limit load of 7.80P （P is the design load）and the model anchor system yield load characteristic point of 5.25P.
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Key words:
- tunnel anchorage /
- scaled model experiment /
- bearing characteristic /
- safety factor
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表 1 岩体物理力学参数试验建议值
Table 1. Test proposed values of the physical and mechanical parameters of the rockmass
参数 试验值 试验建议值 天然块体密度/（g•cm−3） 2.61～2.70 2.50～2.60 泊松比 μ 0.24～0.25 0.30～0.35 变形模量/GPa 0.95～5.39 1.0～2.0 抗拉强度/MPa 2.50～3.90 0.05～0.10 岩体摩擦系数 0.79～1.12 0.70～0.80 岩体黏聚力/MPa 0.28～0.62 0.35～0.45 砼/岩接触面摩擦系数 1.02～1.08 0.65～0.75 砼/岩接触面黏聚力/MPa 0.37～0.50 0.30～0.40 
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表 2 隧洞锚区域围岩BQ法质量分级结果
Table 2. BQ classification of rockmass at tunnel anchor
位置 RC/MPa KV BQ系数 质量分级 实桥锚 33.2 0.42 295 Ⅳ 模型锚 24.26 0.36 253 Ⅳ
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表 3 锚塞体抗拔安全系数计算结果
Table 3. Security coefficient of pull strength of anchoring concrete-plug
参数 定义 取值 接触面抗剪断摩擦系数 f ′ 据现场岩石力学试验取值 0.65 接触面抗剪断粘聚力 c′/kPa 据现场岩石力学试验取值 300 接触面积 A/m2 A = 单锚中截面周长 × 锚体长度 2166 结构自重垂直于滑动面的分量 WF/kN 单锚中截面面积 × 锚体长度 × 混凝土重度 × cos 36° 232368 结构自重沿拉拔方向的分量 WL/kN 单锚中截面面积 × 锚体长度 × 混凝土重度 × sin 36° 147028 主缆拉力设计值 P/kN 设计荷载 267035 抗拔安全系数 K 3.48
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表 4 7.00P到7.80P荷载重点位置测点沿拉力方向的变形
Table 4. Deformation comparison of key position measuring points between 7.00P and 7.80P
mm 测点 7.00P 变形 7.80P 变形 差值 g3# 6.41 7.60 1.19 g4# 6.82 8.09 1.27 g6# 5.23 6.65 1.42 g7# 4.76 6.15 1.39 D2-2 6.21 7.15 0.94 D2-3 6.59 7.56 0.97
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