剪切速率对黏性土混凝土界面抗剪强度影响的试验研究

通过自行研制的大型恒刚度桩土界面直剪仪,进行6种剪切速率的黏性土混凝土界面剪切试验,探讨剪切速率对黏性土混凝土界面抗剪强度的影响规律。结果表明:在黏性土混凝土界面,超孔隙水压力随着剪切速率的提高而增大;法向应力和剪切速率通过影响超孔隙水压力大小,决定黏性土混凝土界面剪切峰值强度和剪切破坏位移的大小;剪应力剪切位移关系曲线由基本一致变化到一定范围内产生偏离,且法向应力和剪切速率越大偏离越显著,并出现明显的应变软化现象;剪切速率从0.4mm/min增加至5.0mm/min,黏性土混凝土界面抗剪强度减小幅度增大,摩擦系数减小0.1,有效黏着力的变化介于0.81～5.93kPa之间。

Experimental research on effect of shear rate on shear strength of clayey soil-concrete interface

The direct shear tests of clayey soil-concrete interface with six series of shear rates were carried out by using the self-developed large-scale constant normal stiffness pile-soil interface shear apparatus. The effect of shear rate on shear strength of clayey soil-concrete interface was explored in this paper. The test results indicate that excess pore water pressure increases with the increased shear rate. The excess pore water pressure is influenced by both normal stress and shear rate, which is closely related to shear peak strength and shear failure strain of clayey soil-concrete interface. The shear stress-shear strain curves are basically identical at the beginning and then deviate in a certain range, which deviate the more obviously and present significant strain-softening appearing, with higher normal stress and faster shear rate. The decreased magnitude on shear strength of clayey soil-concrete interface increases, and the friction coefficient decreases to 0.1 and the effective adhesive force varies from 0.81 kPa to 5.93 kPa as the shear rate increases from 0.4 mm/min to 5.0 mm/min.