苗尾水电站砾质土心墙堆石坝反滤Ⅰ料静力特性试验研究

Experimental study on static characteristics of filter material Ⅰ for construction of earth-rockfill dam with gravel-soil core wall for Miaowei Hydropower Station

从优化苗尾水电站砾质土心墙堆石坝反滤Ⅰ料中小于0.075 mm颗粒含量控制指标的工程需要出发,开展了关于反滤Ⅰ料中小于0.075 mm颗粒含量控制指标的系列静力特性试验,分析了将小于0.075 mm颗粒含量控制指标从5%优化至8%以后的渗透特性、固结特性、三轴静力剪切特性和反滤协调特性。结果表明：反滤Ⅰ料渗透系数可满足设计要求,应力~应变曲线具有非线性、压硬性和弹塑性等一般规律,基本符合邓肯—张模型;优化反滤Ⅰ料中小于0.075 mm细料含量对于提高反滤料与心墙及堆石料的变形协调能力是有利的;在坝体填筑期间适量洒水能够提高反滤Ⅰ料的压实干密度,减少浸润线以下的坝体由于浸水引起的附加变形,且反滤Ⅱ料能够对反滤Ⅰ料起到明显的反滤保护作用;将反滤Ⅰ料中小于0.075 mm细料含量控制指标从5%优化至8%从静力力学特性分析是完全可行的,但是对于其动力及震动液化特性还需要进一步深入研究。

From the aspect of the engineering necessity of the control index for the content of the grain with the particle size of 0. 075 mm within the filter material I for the construction of the earth-rockfill dam with gravel-soil core wall for Miaowei Hydropower Station,a series static characteristic tests on the grain content of 0. 075 mm within the filter material I are made,and then the characteristics of the permeability,consolidation characteristics,triaxial static shear properties and filtration coordination properties of the filter material after the content of the grain with the particle size of 0. 075 mm being optimized from 5% to 8%are analyzed as well. The result shows that the permeability coefficient of the filter material I can meet the design requirement and the stress-strain curve has the general law of non-linear,hardness under pressure,elastic-plastic behavior,etc.,which is basically coincided with Duncan-Chang model. The optimization of the content of the grain with the particle size of 0. 075 mm within the filter material I is adaptable for the capacity to coordinate the deformation among the filter material,the core wall and the rock filling material. The suitable water spraying during the dam filling construction can increase the compacted dry density of the filter material I and reduce the additional deformation caused by the inundation of dam body under the saturation line,moreover,the filter material II can play a role of protecting the filter material I. The optimization of the content of the grain with the particle size of 0. 075 mm within the filter material I from 5% to 8% is feasible from the aspect of the analysis of the static mechanical properties,but its characteristics of motivity and vibration liquefaction are necessary to be further and deeply studied.