河谷形状对沥青混凝土心墙坝变形特性的影响

Influences of valley topography on deformation properties of asphalt concrete core wall dam

将河谷形状与堆石材料的力学特性联系起来,定义了河谷宽度系数、河谷边坡陡缓系数和河谷非对称系数等3个动态参数来描述河谷形状。利用新定义的河谷形状参数研究其对沥青混凝土心墙坝变形特性的影响,结果表明:河谷宽度直接影响沥青混凝土心墙底部应力拱效应的强弱,河谷宽度系数越小,狭窄河谷地形导致的应力拱效应越明显,从而可能诱发心墙水力劈裂;河谷边坡的陡缓影响沥青混凝土心墙两侧拉应力的分布规律和量值大小,河谷边坡陡缓系数增大,沥青混凝土心墙左右两侧的拉应力区范围变小但量值增大;沥青混凝土心墙两侧的沉降差随河谷非对称系数的增大而明显增加,据此初步给出了区分河谷对称性的界限值;河谷形状对沥青混凝土心墙坝的三向位移均会产生一定约束作用,河谷宽度对坝体位移的影响最为显著。

According to the relationships between the valley shape and the mechanical properties of rock-fills , thenew valley topography parameters which are described by using a valley width coefficient fi, a valley slopecoefficient S and a valley asymmetry coefficient y have been given in this paper. And then the new parameters forvalley topography are used to study the influences of the valley topography on the deformation and stresscharacteristics of an asphalt concrete core wall dam. The results of this study show that the valley width coefficientshave direct influences on the degree of the arch effect caused by stresses taking place at the bottom of the asphaltconcrete core-wall. The smaller the valley width coefficients, the stronger the arch effect caused by the deep narrowvalley becomes, and the hydraulic fracturing may be taken under such conditions in practical engineering. When thevalley slope coefficients increase, the tensile stress area in the asphalt concrete core wall becomes smaller and thevalues of tensile stress become larger. The differential settlements on the dam increase obviously with the adding of avalley asymmetry coefficient. A critical value of the asymmetrical valley is proposed according to the differentialsettlements between left and right sides of the dam. The foundation topography can restrain the deformation of thedam and the valley widths have the most obvious impacts upon the displacement of the asphalt concrete corewall dam.