| 三峡库区巫峡段典型岩体劣化特征研究 |
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| 引用本文： | 闫国强,黄波林,代贞伟,秦臻.三峡库区巫峡段典型岩体劣化特征研究[J].水文地质工程地质,2020,47(4):62-72. |
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| 作者姓名： | 闫国强 黄波林 代贞伟 秦臻 |
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| 基金项目： | 国家重点研发计划项目(2018YFC1504800)；三峡后续工作地质灾害防治项目(0001212019CC60001；2018102849)；中国地质调查局地质调查项目（DD20190637） |
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| 摘 要： | 三峡工程形成了在高程145~175 m之间的周期性水位波动，促使库区灰岩岸坡劣化损伤加剧，稳定性急剧衰减。其中巫峡段灰岩岸坡受库水长期的物理化学作用，宏观劣化现象最为明显，局部顺层岸坡底部受侵蚀劣化脱空，岩层出露，存在潜在的滑移-拉裂破坏。文章借助三维激光扫描点云技术对岩体表层宏-细观劣化进行了定量化观测，发现岩体劣化主要沿着泥质填充条带等薄弱结构面进行，现场“刀砍纹”状溶蚀沟槽的差异劣化与白云石和方解石抗溶蚀性能密切相关。室内干湿循环劣化试验进一步表明:三叠系大冶组(T1d)泥质条带灰岩的劣化速率明显高于三叠系嘉陵江组(T1j)白云质灰岩，这与两种岩性的矿物成分及孔隙微观结构组成相关，且随着循环周期增加，两种岩样的物理力学性质呈现出不同程度的衰减；基于核衰变劣化控制式进行回归，R2高达0.861 9~0.999 3。引入劣化常数λ、半衰期T1/2对两种岩性劣化特征进行描述，发现同一岩性不同物理参数对应的劣化常数λ、半衰期T1/2不同，呈现“簇状”分布，与室内试验数据表现一致；运用劣化控制式时要考虑现场岩体由于各种结构面的存在，岩体会加速劣化，需要对劣化控制方程和力学强度进行相应折减。文章结合现场宏-细观劣化现象以及室内干湿循环，构建了物理意义明确的基于核衰变的劣化控制方程，为类似灰岩岸坡劣化评估预测与稳定性分析提供参考。
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| 关 键 词： | 岩体劣化 灰岩岸坡 干湿循环试验 核衰变劣化方程 三峡库区巫峡段 |
| 收稿时间： | 2020-03-20 |
A study of the deterioration effect of limestone bank slope rock mass at the Wuxia section of the Three Gorges Reservoir area |
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| Abstract: | The periodic fluctuation of water level elevation between 145 and 175 m is formed due to the Three Gorges Project, which leads to the increasein deterioration damage and reductionin stability of the limestone reservoir slope in the Three Gorges Reservoir area.The limestone bank slope at the Wuxia section is affected by long-term physical and chemical actions, and the macroscopic deterioration is mostobvious. Local consequent bed slope bottom is degraded by erosion and is stripped away, and rock strata are exposed, leading to potential slip-tension failure.The macro-micro deterioration of rock mass surface was quantitatively observed by using 3D laser scanning point cloud technology. It is found that the deterioration of rock mass was mainly along the weak structural planes such as the muddy filling strips. The differential deterioration effect of knife-cut grooves in situ is closely related to the corrosion resistance of dolomite and calcite.The indoor dry-wet cyclic deterioration experiments further show that the deterioration rate of T1d argillaceous strip limestone is significantly higher than that of T1j dolomitic limestone, which is related to the mineral compositions and pore microstructure of the two lithologies. With the increasing cycle period, the mechanical properties of the two rock samples show different degrees of attenuation. Based on the general governing equation regression of nuclear decay deterioration, R2 is as high as 0.861 9~0.999 3. Two kinds of lithological deterioration characteristics are described by introducing the deterioration constant λ and half-life T1/2. It is found that the deterioration constant λ and half-life T1/2 corresponding to different physical parameters of the same lithology are different, showing a “cluster” distribution, which is consistent with the indoor experimental data. When using the deterioration control equation obtained from laboratory experiments, it is necessary to consider that the deterioration of rock mass will be accelerated due to the existence of various structural planes in the field, and the deterioration control equation and mechanical strength need to be reduced accordingly. In this paper, a deterioration control equation based on nuclear decay with clear physical meaning is constructed according to the macro-micro deterioration phenomena in situ and the indoor dry-wet cycle experiment, which may provide a reference for the evaluation, prediction and stability analysis of similar limestone bank slope deterioration in the Three Gorges Reservoir area and in the world. |
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