大型水利水电工程施工水力控制及灾害预测关键技术

Key Technologies of Hydraulic Control and Predictive Disaster Control for the Construction of Large-scale Water Conservancy and Hydroelectric Projects

针对我国西部山区大型梯级水利水电工程施工面临复杂环境下的导截流标准及风险控制、陡坡隧洞导流安全水力控制、深厚覆盖层河床安全经济截流水力控制、导截流过程灾害预测控制等新问题,经过长达28 a的系统研究,解决了大型梯级水利水电工程施工导截流水力控制和灾害减免的相关技术难题。包括:(1)构建了多梯级同建条件下施工导流系统风险评估模型和基于水文实时监测预报的截流标准决策模型,提出了满足安全性、经济性要求的标准优选方法,修订了施工导流设计规范;(2)揭示了陡坡隧洞易发生明满交替流等不良水力特性的成因及机制,提出了进口隔流浮堤消涡、锐缘进口减免明满交替流、出口压坡增压等复合式水力控制技术,保障了隧洞运行安全,提出的钢筋笼柔性毯和过水围堰分级整流防护新技术,解决了大流量、深厚覆盖层条件下度汛安全难题;(3)提出了考虑水深、流速分布、河床糙度、绕流系数影响的天然截流块体稳定实用计算公式以及六面体钢筋石笼人工截流块体稳定计算公式,计算精度更接近实际;(4)发明了内附透水反滤土工膜的四面体钢筋笼和圆柱线体新型截流材料;(5)提出了"水下宽戗堤"新技术,减轻了截流难度;(6)首次提出了高陡岸坡滑坡涌浪过程中第二次涌浪为首浪的论点,建立了首浪高度实用计算公式、涌浪产生与传播预测模型;(7)提出了土石围堰溃决过程与洪水演进高分辨率模拟技术。这些关键技术对于推动相关学科发展、加快水利水电行业科技进步起到了巨大作用。

The construction of large-scale cascade hydropower projects in mountainous area of west China has encountered new problems in complex circumstances,such as design standards for river diversion and closure and risk control,safe hydraulic control of steep slope tunnel diversion,safe and economic hydraulic control of river bed closure with thick overburden layer,and predictive control of disasters in river diversion and closure process,among others.After 28 years of systematic research,some technical problems related to hydraulic control and disaster reduction for large-scale cascade hydropower projects have been solved.The achievements are presented as follows:(1)A risk assessment model of diversion system and a decision-making model for the standard of river closure based on real-time hydrological monitoring and forecasting were built for synchronous construction of multiple cascade projects;standard selection methods were proposed to meet safety and economy requirements,and design specifications of construction diversion were modified.(2)The causes and mechanisms of adverse hydraulic characteristics such as alternative free surface and pressure flow in steep-slope tunnels were revealed;some composite hydraulic control techniques were proposed to guarantee tunnel safety,including obstructive floating embankment for vortex reduction in the upstream of tunnel inlet,inlet form with sharp edges alleviating alternative free surface and pressure flow in tunnel,and outlet form with downward slope for increasing pressure in tunnel;an innovative protection technology has addressed the safety problem in flood season in the presence of large flow and thick cover layer by adopting flexible blanket of reinforced cage and multi-stage flow rectifying for overflow cofferdam.(3)An innovative and practical formula for the stability calculation of natural closure blocks was proposed in consideration of water depth,flow velocity distribution,river bed roughness,and circumfluence coefficient;a formula for the stability calculation of artificial closure block of hexahedron stone-gabion reinforced cage was also established.Both the formulae are of good precision close to practice.(4)A tetrahedral reinforced cage with infiltrated geomembrane embedded and a new type of river closure material of cylindrical line bar were invented.(5)The technology of“wide underwater dike”was proposed to reduce river closure difficulty.(6)The second surge in the process of high-steep bank landslide was defined as the first wave for the first time;a practical formula for the height of first wave was obtained,and a model for predicting the generating and spreading of surges was built.(7)A high-resolution technology for simulating the process of earth-rock cofferdam breaking and flood routing was developed.These key technologies have boosted the development of relative disciplines and stimulated the technological progress in water conservancy and hydropower industry.