库水变动下巨型堆积体变形失稳诱发涌浪特征研究

Surge characteristics induced by deformation and instability of giant accumulation body under fluctuating reservoir water levels

摘要

【目的】库区岸坡在蓄水过程中易因水力作用发生变形失稳，进而产生涌浪灾害，对库区基础设施和居民生命安全构成严重威胁。为揭示水位变动条件下堆积体岸坡失稳变形演化过程及诱发涌浪特征，【方法】以雅砻江某水电站库区巨型堆积体为研究对象，通过现场地质调查获取裂缝产状与变形特征，基于离散元数值模拟岸坡变形演化全过程，利用水科院法和潘家铮法计算涌浪高度，分析滑速、体积与地形条件的协同效应。【结果】研究结果显示，堆积体变形呈现出“蠕动-等速-加速”三阶段演化特征，坡脚岩体强度劣化(黏聚力下降35%~65%,内摩擦角降低18%~22%)是变形启动主因；锁固段高程(2 905.65 m和2 978.08 m)的稳定性是控制变形阶段转化的关键阈值，其失效后滑体加速度从0.06 m/s²跃升至0.418 m/s²;涌浪传播呈现显著非线性衰减特征，水科院法与潘家铮法计算的对岸最大浪高分别为80.68 m和53.53 m、隧道口分别为15.1 m和15.09 m以及坝址处分别为3.63 m和1.13 m,差异揭示了地形放大效应。【结论】研究结果表明变形-涌浪耦合机制表现为“水力劣化-锁固段失效-滑速突变-涌浪传播”的链式响应，锁固段稳定性是防控涌浪灾害的核心。研究成果可为类似库区滑坡涌浪预警提供理论依据。

Abstract

[Objective] During reservoir impoundment, reservoir-bank slopes are prone to deformation and instability due to hydraulic effects, which may subsequently generate surge hazards and pose serious threats to infrastructure and human safety in the reservoir area. The evolution process of instability-induced deformation of accumulation-body slopes and the characteristics of surge generation under fluctuating water levels are revealed. [Methods] A giant accumulation body in the reservoir area of a hydropower station on the Yalong River was selected as the research object. Field geological surveys were conducted to obtain fracture occurrence and deformation characteristics. The entire slope deformation evolution process was simulated using discrete element numerical modeling, while surge heights were calculated using the China Institute of Water Resources and Hydropower Research(IWHR) method and the Pan Jiazheng method. The synergistic effects of sliding velocity, volume, and terrain conditions were analyzed. [Results] The result showed that the deformation of the accumulation body exhibited a three-stage evolution characteristic of “creep, constant velocity, and acceleration.” The strength degradation of rock mass at the slope toe(cohesion decreased by 35% to 65% and internal friction angle reduced by 18% to 22%) was identified as the main cause of deformation initiation. The stability of locked segments at elevations of 2 905.65 m and 2 978.08 m served as the critical threshold controlling the transformation of deformation stages. After their failure, the sliding body acceleration increased from 0.06 m/s² to 0.418 m/s². Surge propagation showed significant nonlinear attenuation characteristics. The maximum surge heights calculated by the IWHR method and the Pan Jiazheng method at the opposite bank were 80.68 m and 53.53 m, respectively; at the tunnel entrance were 15.1 m and 15.09 m, respectively; and at the dam site were 3.63 m and 1.13 m, respectively. The differences revealed the terrain amplification effect. [Conclusion] The deformation-surge coupling mechanism is manifested as a chain response of “hydraulic degradation-locked segment failure-abrupt change in sliding velocity-surge propagation, ” with the stability of locked segments being the core for surge disaster prevention and control. A theoretical basis for early warning of similar landslide surges in reservoir areas is provided by these result.

关键词

堆积体变形失稳 / 锁固段 / 涌浪灾害 / 耦合机制 / 滑坡 / 离散元 / 水电站 / 链式响应机制

Key words

accumulation body deformation and instability / locked segment / surge disaster / coupling mechanism / landslide / discrete element / hydropower station / chain response mechanism

基金资助

国家自然科学基金项目(42293350)

国家自然科学基金项目(42293353)

地质灾害防治与地质环境保护国家重点实验室开放基金资助项目(SKLGP2025K012)

中国电建集团贵阳勘测设计院有限公司博士后基金项目“超深卸荷高陡边坡时效变形机理及稳定性研究”(YJBSXM250001)

四川省科技计划资助(2026NSFSC1191)