高压冻(融)土-结构接触面剪切应力-应变关系

为揭示深厚表土冻融土-混凝土结构接触面剪切力学特性,利用改进的DRS-1高压直残剪试验系统,开展系列高法向应力、升温条件下冻(融)土-结构接触面直剪试验,总结高应力作用下不同融化程度冻(融)土-结构接触面剪切应力-应变关系曲线的基本特征.通过试验分别建立峰值前和考虑应变软化特征的高应力、升温条件下冻(融)土-结构接触面剪切应力-应变经验方程,探讨接触面剪切应力极值和初始剪切模量随法向应力水平、融化程度等的变化规律.结果表明:随融化程度的加深,冻(融)土-结构接触面剪切应力-应变关系曲线形态由具有应变软化特征逐渐转变为具有应变硬化特征;当接触面剪切应变较小时(峰值前),标准的双曲线模型对高应力、升温条件下冻(融)土-结构接触面剪切应力-应变关系仍具有良好的适用性;而具有应变软化特征的全过程剪切应力-应变关系可采用改进的双曲线模型描述.

Shear stress-strain relation of frozen/thawed soil-structure interface under high pressure

To reveal the shear mechanical characteristics of the interface between deep alluvium frozen/thawed soil and concrete structure, a series of direct shear tests were carried out under high normal stress and thawing condition by using an improved DRS-1 high pressure direct/residual shear test system. Basic shear mechanical characteristics of the interface between frozen/thawed soil and structure were summarized. Based on the test results, empirical equations of shear stress-strain relation of interface between frozen/thawed soil and structure under different high normal stress and thawing conditions were established, considering pre-peak stress and strain softening behavior, respectively. Effects of normal stress and thawing degree on the maximum shear stress and the initial shear modulus were discussed. Results show that the pattern of shear stress-strain curves transformed gradually from strain softening to strain hardening as the process of thawing. When the shear strain was small (pre-peak), the general hyperbolic model could reasonably describe the shear stress-strain relation of the frozen/thawed soil-structure interface. Furthermore, an improved hyperbolic model in consideration of strain softening behavior was proposed to describe the whole shearing process under different high normal stress and thawing conditions.