切向应力幅值对土与结构接触面切向变形的影响研究

Influences of shear stress amplitude on tangential deformation behavior of a gravel-structure interface

运用80t大型三维多功能土工试验机,进行了应力控制往返圆形剪切路径下粗粒土与结构接触面三维直剪试验,分析了切向应力幅值对接触面切向位移、非共轴角和剪切柔度等切向变形特性的影响规律。试验结果表明:应力控制往返圆形路径下,接触面产生了明显的x向和y向位移及其偏移、非共轴角、剪切柔度和剪切耦合效应,呈现出显著的三维特性。切向应力幅值达到临界应力幅值时,接触面切向位移幅值及剪切柔度峰值随循环剪切基本保持不变;剪切柔度初始峰值与非共轴角稳定值存在对立统一关系。切向应力幅值主要影响接触面力学特性参数数值,对其之间关系形式影响很小。切向应力幅值越大,接触面x向和y向位移幅值越大,向负向偏移程度越大;非共轴角稳定值越小,剪切柔度峰值越大。非共轴角稳定值、剪切柔度初始峰值与切向应力幅值间存在良好的关系,可用建议的计算公式进行描述,为接触面三维力学特性的本构建模奠定了基础。

A series of interface tests between gravel and structure are conducted in stress-controlled two-way circular cyclic shear path by using the large-scale direct-shear apparatus, and the effects of shear stress amplitude on the tangential deformation performances of the interface, including tangential displacement, non-coaxial angle and shear flexibility, are addressed. The test results show that the interface presents distinct 3D behavior subjected to two-way circular cycling of shear stress, such as distinct tangential displacements in the x and y directions and their migration, non-coaxial angle, shear flexibility and shear coupling effect. The tangential displacement amplitude and the peak shear flexibility almost remain invariable with cyclic shearing when the shear stress amplitude reaches the critical stress amplitude. The unity of opposites is discovered between the stabilized non-coaxial angle and the initial peak shear flexibility of the interface. The shear stress amplitude primarily impacts the magnitudes of the performance parameters of the interface, instead of their relationship patterns.Increasing the shear stress amplitude results in magnified tangential displacement amplitudes in the x and y directions, enlarged migration of the tangential displacements towards the negative directions, increased peak shear flexibility and decreased stabilized non-coaxial angle. The stabilized non-coaxial angle and the initial peak shear flexibility have a close relationship with the shear stress amplitude, and can be described using the proposed formulas, which may provide a sound basis for the 3D constitutive modeling of the soil-structure interface.