【摘要】 通过大型振动三轴试验研究了先期振动荷载对高土石坝筑坝材料抵抗地震变形能力的影响,研究结果表明:经受过先期动应力作用的土石料,再次经受动应力作用时,其抵抗变形的能力明显提高,这是由于在初始动应力作用下,土石料颗粒破碎及试样内部重定向排列大部分已经完成,再次经受动应力作用时,土石料颗粒破碎的程度将降低,试样内部重定向排列的难度将加大,从而使得其变形量减小,抵抗变形的能力提高。抵抗变形的能力提高的幅值与土石料本身的性质、再次经受的动应力与先期动应力的比值,即先期动应力和再次经受的动应力大小有关。根据试验结果建立了先期振动对粗粒料变形能力影响的一般表达式,该表达式表明:先期振动对粗粒料抵抗变形能力的影响仅与k值有关,k反映了粗粒料对先期振动作用的敏感度,表示粗粒料经先期动应力作用后,在再次经受动应力作用时,粗粒料内部重定向排列和颗粒破碎的难易度,k值越小,粗粒料对先期振动的敏感性越大,反之则越小,k值大小与粗粒料本身的矿物组成有关,而与其自身的岩性、颗粒形状、级配、密度等没有关系。更多还原

【Abstract】 Using dynamic triaxial tests, the effect of previous cyclic loading on capability of anti-deformation dam materials is studied. The results show that the anti-deformation capability is enhanced obviously when the dam materials are stabilized under the previous cyclic loading. It is considered that the further appropriate cyclic loading can not cause more particle breakage and internal redirection as are basically completed under the initial dynamic stress, leading to enhancing of anti-deformation capability and reduction of deformation. A general expression is proposed to describe the effect of the previous cyclic loading on the deformation of coarse materials. The anti-deformation capability of coarse materials only relates with k, which shows the sensitivity of the coarse materials to the previous cyclic loading, and it represents the degree of difficulty of particle breakage and internal redirection under later cyclic loading when they are stabilized under the previous cyclic loading. The value of k just relates with the absorption force and has nothing to do with parent rock, shape, gradation and density and so on. With the decrease of k, the sensitivity of the coarse materials to the previous cyclic loading is larger accordingly, and vice versa.更多还原