Research on hydraulic and mechanical design of flowthrough rockfill dams.

本研究的目的是为干旱和半干旱地区为控制洪水或开发水资源而建造的“穿流式堆石坝”制订水力设计方案。在研究的第一年，对堆石料流的水头损失特性进行了研究并建立了模型。在研究的第二年，研究了堆石坝结构体的流传递性，并提出了一些实用的设计方案。研究结果总结如下：1)通过室内一维渗透性试验，测量了水力梯度与堆石柱流速的关系。用Forchheimer方程很好地模拟了堆石料流的水头损失特性。成功地在水头损失方程中引入水力平均孔洞半径来描述岩石颗粒形状、孔洞大小和几何形状对堆石体流动的影响。(2)采用有限元数值计算方法，编制了更详细的数值计算程序，以估计堆石料结构流的水头损失特性。通过与室内水槽试验的比较，验证了上述水头损失方程的适用性以及所编制的有限元数值程序的有效性。3)采用纳入水头损失方程的有限元数值程序确定了小到大尺寸穿流堆石坝的级流量额定值曲线。结果表明：堆石料结构的流量随上游水位呈指数增长，且流量温度对分级流量曲线没有影响；4)采用有效水力梯度的概念，确定了统一的分级流量等级曲线，由此可以方便、简单地估计堆石坝的流量。结果表明，采用一种简单实用的设计方案来确定堆石堆构筑物的水力特性是可行的。少

The purpose of the RESEARCH is to develop a hydraulic design scheme of "flowthrough rockfill dams" which have been constructed for flood control or water resource development in arid and semi-arid region. In the first year of the RESEARCH the head loss property of flow through rockfill was investigated and modeled. In the second year of the RESEARCH the flow transmissibility of the rockfill structures was investigated and some practical design scheme was proposed. The research results are summarized as follows :1) The laboratory one-dimensional permeability tests were conducted to measure the relationship between the hydraulic gradient and the velocity of flow through rockfill column. The head loss property of flow through rockfill was well modeled by using the Forchheimer equation. The hydraulic mean radius of voids was successfully introduced into the head loss equation to describe the effects of rock particle shape, void size and geometry on the flow through rockfill.2) The FEM nume … More rical code was developed to estimate the head loss property of flow through rockfill structures. By comparing the FEM estimation with the laboratory water flume tests the applicability of the head loss equation proposed above as well as the validity of the FEM numerical code developed were examined.3) The FEM numerical code incorporating the head loss equation proposed was applied to determine the stage-discharge rating curve of small to large size flowthrough rockfill dams. It was shown that the flow discharge through rockfill structure increases exponentially with the upstream water level, and that no effect of flow temperature on the stage-discharge rating curve can be seen.4) A unified stage-discharge rating curve was determined by employing the concept of effective hydraulic gradient, from which the flow discharge through rockfill structures can be easily and simply estimated. It was concluded that a simple and practical design scheme to determine the hydraulic properties of rockfill structures nay be feasible. Less