Abstract: The effect of temperature on the mechanical behaviors of slope interlayer was investigated on direct shear test device with temperature control heating system. Seven interlayer specimens with different mix proportions of bentonite and river sand at varied moisture content (10%, 13%, 15%) were prepared for the test. The shear strength indexes of slope interlayer specimens at different temperatures were measured to further examine the failure mechanism. Results demonstrated that at a given temperature, cohesion and shear strength of interlayer specimens decreased with the shrinking of bentonite content; while with the climbing of temperature, specimens of high bentonite content experienced dramatic decline, gentle decline, and then finally dramatic decline again in terms of cohesion and shear strength. Moreover, such relation curve tended to be gentle and finally displayed a linear decline with the rising of moisture content. As temperature decreased, the resultant force of water in slope interlayer decreased correspondingly, which weakened the microstructural force among soil particles, resulting in a sharp reduction of cohesion; when temperature exceeded 50 ℃, cohesion decreased dramatically again because of slip of soil particles, giving rise to a critical failure state. Therefore, cohesion is a key factor inducing the failure of interlayer specimen, and the critical point of cohesion reducing dramatically again could be regarded as the indicator of the failure of slope interlayer.

Key words: slope with interlayer, temperature, shear strength, failure mechanism, moisture content