砂砾石垫层料与混凝土面板接触面特性的大型单剪试验研究

Mechanical behaviors of interface between sand-gravel cushion material and concrete face slab by large-scale simple shear tests

采用自主研制的低摩阻叠环式双向静动剪切试验机,考虑面板与垫层间喷涂和不喷涂乳化沥青两种情况,进行混凝土面板与砂砾石垫层料之间的大型剪切试验,研究混凝土面板与垫层料接触面的力学特性,基于Clough和Duncan非线性弹性本构模型整理出接触面模型参数,并探讨了乳化沥青在接触面剪切变形中的作用机制。研究表明:①不喷涂乳化沥青时,接触面应力随着剪切位移的增加逐渐变大,接触面剪应力与位移呈现出很好的双曲线关系。喷涂乳化沥青时,接触面剪应力与剪切位移在峰值强度前呈现出很好的双曲线关系,在峰值强度后,呈现出一定的应变软化特性,法向应力越低,表现越为明显;②两种情况下,随剪切位移的增加,上盒土体变形逐渐发展,并由上到下逐渐增加,最大的相对错动位移均发生在混凝土面板与垫层之间的接触面处,表明接触面的抗剪强度小于砂砾石垫层的抗剪强度;③法向应力对叠环的剪切位移有较大影响,法向应力越大,同一高度处叠环的剪切位移越大;在相同的剪切位移和法向应力作用下,喷涂乳化沥青时叠环水平位移均小于不喷涂时叠环水平位移;④乳化沥青对接触面的力学参数有很大的影响,采用Clough和Duncan非线性弹性本构模型拟合时,与不喷涂乳化沥青时相比,喷涂乳化沥青的接触面其劲度系数、指数及强度指标均有大幅度降低,剪切过程中乳化沥青形成了完整的过渡层来隔离砂砾石垫层料和混凝土面板的直接接触,并起到很好的阻隔–润滑效果。

A series of large-scale shear tests are performed to study the contact characteristics between sand-gravel cushion and concrete structure with two types of interfaces, coated with and without emulsified asphalt by a self-developed large-scale bidirectional low friction laminar-ring simple shear apparatus. The nonlinear elastic constitutive model parameters based on Clough and Duncan of the interfaces are determined, and the effects of emulsified asphalt on shear deformation mechanism of the interface are discussed. The results show that:(1) With the increasing shear displacement, the shear stress of interface coated without emulsified asphalt increases and the curves of shear stress and shear displacement exhibit a good hyperbolic relationship. The curves of shear stress and shear displacement of interface coated with emulsified asphalt exhibit a good hyperbolic relationship before the peak strength. Certain strain softening properties are shown after the peak strength, which is different from that coated without emulsified asphalt. The lower the normal stress, the more obvious it is.(2) For the both cases, with the increasing shear displacement, the deformation of soils in the upper box develops, and gradually increases from top to bottom and the largest relative movement displacement occurs in the contact surface between concrete slabs and cushion layer, which show that the shear strength of the interface is less than that of the sand-gravel cushion.(3)The normal stress has a great influence on the shear displacement of the laminar ring, and the larger the normal stress, the greater the shear displacement of the laminar ring at the same height. Under the same shear displacement and normal stress, the horizontal displacement of the laminar ring coated wtih emulsified asphalt is less than the horizontal displacement coated without emulsified asphalt.(4) The emulsified asphalt has a great influence on the mechanical parameters of the interface. Compared with the interface coated without emulsified asphalt, the parameters of Clough and Duncan nonlinear elastic constitutive model of the interface coated with emulsified asphalt, such as the stiffness coefficient, index and intensity index, are greatly reduced. The emulsified asphalt forms a complete transition layer to isolate the direct contact between sand-gravel cushion and concrete face, and has a very good obstructing-lubricating effect in the shear process.