泸定水电站坝基覆盖层深部潜蚀对土骨架变形影响评价试验研究  

Experimental study and evaluation on influence of deep alluvium foundation suffusion on deformation of soil skeleton in foundation of Luding Hydropower Station

作　　者：金伟 邱子源 张丹 向雷[2] 杨林骏 罗玉龙 JIN Wei;QIU Ziyuan;ZHANG Dan;XIANG Lei;YANG Linjun;LUO Yulong(Power China Chengdu Engineering Corporation Limited,Chengdu 610072,China;College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210024,China;College of Dayu,Hohai University,Nanjing 210024,China)

机构地区：[1]中国电建集团成都勘测设计研究院有限公司,四川成都610072 [2]河海大学水利水电学院,江苏南京210024 [3]河海大学大禹学院,江苏南京210024

出　　处：《岩土工程学报》2024年第4期705-715,共11页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51679070);国家重点研发计划项目(2017YFC1502603);中国科学院青海盐湖研究所基础研究青年创新交叉团队项目(islJCTD-2022-2);湖南省水利科技项目(XSKJ2021000-35,XSKJ2022068-37)。

摘　　要：泸定水电站因坝基覆盖层深部(1)层潜蚀诱发涌水险情,潜蚀过程中大量细颗粒持续流失能否诱发明显土骨架变形关系到电站自身、下游梯级电站及泸定县城的安全。土体颗粒级配、应力状态及细颗粒流失比例等均有可能影响土骨架变形,但其影响机制尚不清楚。为全面评价(1)层潜蚀对土骨架变形的影响,自行研制了可以模拟现场(1)层土体原始级配特征和应力状态的高应力、大直径的土体渗透稳定试验装置,建立了土骨架发生明显变形的判据,即潜蚀过程中试样累计体积应变大于等于1%时,表明土骨架已发生明显变形,提出了细颗粒运移比作为衡量细颗粒流失比例的评价指标。针对(1)层土体,开展了一系列极端不利水力条件下的渗流应力耦合潜蚀试验研究,重点探讨了颗粒级配、应力状态及细颗粒运移比对土骨架变形的影响规律。研究表明:所有试样潜蚀全过程的累计体积应变介于0.1%~0.49%,均小于1%,即(1)层土体中细颗粒大量甚至全部流失也不会诱发明显骨架变形,(1)层潜蚀诱发防渗墙开裂、折断,甚至突然溃坝的风险不大。颗粒级配显著影响细颗粒运移比、潜蚀临界和破坏坡降,5 mm以下颗粒含量越少,细颗粒运移比越大,潜蚀临界和破坏坡降越小;上覆压力对细颗粒运移比影响不大,但对潜蚀临界和破坏坡降影响显著,上覆压力越大,潜蚀临界和破坏坡降越大。研究成果为科学评价泸定水电站深部渗透稳定提供了重要依据,同时,也为其他类似工程安全评价提供了重要借鉴。Suffusion of stratum①in deep alluvium foundation of Luding Hydropower Station induces water gushing incident.Continuous migration of fine particles may induce skeleton deformation,and then it may threat the safety of Luding Dam,downstream cascade hydropower stations and Luding County.Particle size distribution of soil,stress and loss of fine particles may affect the skeleton deformation,but the detailed influence mechanism is not clear.In order to evaluate the influences of stratum①suffusion on the skeleton deformation,a new high stress and large diameter soil suffusion apparatus which can simulate the stress and the characteristics of stratum①particle size distribution is designed,and a criterion distinguishing the obvious skeleton deformation is proposed.When the volumetric strain during suffusion is greater than or equal to 1%,it indicates that the obvious skeleton deformation occurs.A new evaluation index called migration ratio of fine particles is proposed to weigh the loss of fine particles.A list of hydro-mechanical coupling suffusion tests under the extreme adverse hydraulic conditions are performed on stratum①soil to investigate the influences of particle size distributions,stresses and losses of fine particles on the skeleton deformation.The results indicate that the cumulative volumetric strains during suffusion of all specimens range from 0.1%to 0.49%,and are lower than 1%,indicating that significant losses of fine particles in stratum①soil do not induce obvious skeleton deformation,and suffusion of stratum①soil cannot induce the cracks and breaking off of concrete cutoff wall and sudden dam break.The particle size distributions significantly affect the migration ratio of fine particles,hydraulic gradients initiating suffusion and failure.The less the percentage of finer than 5 mm,the larger the migration ratio of fine particles,and the lower the hydraulic gradients initiating suffusion and failure.The overburden pressure has a slight influence on the migration ratio of fine particles,but

关 键 词：深厚覆盖层 潜蚀 细颗粒运移 骨架变形 

分 类 号：TU443[建筑科学—岩土工程]