粗粒土与结构接触面切向变形非共轴现象的试验研究

Experimental study on non-coaxial behavior of gravel-structure interface in tangential direction

粗粒土与结构接触面在切向应力控制三维加载条件下会出现切向变形非共轴现象,对其研究具有重要的理论意义。试验结果表明:单向圆形路径下,非共轴角在第1循环由接近90°逐渐减小,随后围绕某一数值波动,该值基本上不随循环周次变化;单位应力切向位移增量在初始剪切时由零开始增大,切向应力幅值不大时随循环周次逐渐减小,最后基本趋于稳定。往返圆形路径下,相邻2个循环周次的非共轴角符号相反;一个完整循环内,非共轴角由接近90°逐渐减小,最后基本趋于稳定,单位应力切向位移增量由小逐渐变大,然后基本趋于稳定;该稳定值在切向应力幅值不大时随循环周次逐渐减小。单向和往返圆形路径下接触面非共轴角的平均稳定值基本相同,均约为45°。切向应力幅值对接触面切向变形非共轴现象有较大影响;应力幅值越大,非共轴角越小,单位应力切向位移增量则越大。

It is of great significance in theoretical analysis to investigate the non-coaxial behavior of the interface in tangential direction,which may emerge due to 3D loading.The test results in one-way circle shear path demonstrate that：（1） the non-coaxial angle gradually decreases from 90° in the first cycle,and then tends to be a stable value of about 45o with cycles;（2） the tangential displacement increment per stress first increases,subsequently decreases for small stress amplitude after shearing to some extent and then tends to be stable with cycles.As for the test in two-way circle shear path,it is found that：（1） the non-coaxial angle decreases from 90° in each cycle and tends to be stable value of about 45°,which varies little in different cycles but the symbol is opposite in neighboring cycles;（2） the tangential displacement increment per stress increases in a cycle and also tends to be stable,but the stable value decreases with shear cycles for small stress amplitude.It is also indicated that the shear stress amplitude has great influence on the non-coaxial behavior of the interface in tangential direction.