盐渍化冻土-混凝土衬砌接触面直剪试验研究

土与结构接触面的研究一直以来是岩土工程研究的热点之一。为研究位山灌区渠系工程冻害破坏问题,开展了不同盐类型、不同含盐量、不同含水率条件下渠道下卧盐渍土-混凝土衬砌冻结接触面直剪试验研究。结果表明：冻结状态下接触面的应力-位移破坏性状呈脆性破坏,存在明显的峰值应力;剪切变形包括线性变形和非线性变形,线性变形随含水率和含盐量的增大而减小,非线性变形随含盐量的增大而增加;剪切模量随含水率的增加而提高;随含盐量的增加而降低;抗剪强度随含水率的增加而增大,随NaCl含盐量增加而降低,随Na₂SO₄含盐量增加先降低后升高;通过对变形能的分析发现,含水率w=14.7%和w=16.7%时具有相似特征,即NaCl含量为0.5%时,曲线存在极（最）小值。

Direct shear tests of interface between salinized frozen soil and concrete lining

The study of interface between soil and structure has been one of the hot spots in geotechnical engineering research. In order to study the frost damage of canal system in Weishan irrigation district, under the conditions of different salt species, different salt content and different water content, a series of direct shear tests for frozen interface between saline soil and concrete lining have been performed to study the mechanical properties of the frozen interface. The results show that failure model of frozen interface was brittle and an obvious peak stress could be observed. The shear deformation includes linear deformation and nonlinear deformation. The linear deformation decreases with the increase of water content and salt content, and the nonlinear deformation increase with the increase of salt content. The shear modulus increases with the increase of water saturation and decreases with the increase of NaCl concentration. The shear strength increases with the increase of water saturation, decreases as the salt content increases with NaCl, while it decreases first and increases as the salt is Na₂SO₄. Through the strain energy analysis, it is found that the characteristics of frozen interface with water content w=14.7% and w=16.7% are similar, that means when the NaCl content is 0.5% the shear strength is minimum.