橡皮膜嵌入解析解及试验验证

Analytic solution and test validation of membrane penetration

对于粗颗粒土三轴固结排水剪试验,橡皮膜嵌入是影响试验体变测量的最重要因素。通过分析橡皮膜嵌入机制,指出影响膜嵌入量的主要因素如下:有效净压力p、平均粒径d_(50)、橡皮膜厚度tm、弹性模量Em、接触面积mA,以及初始孔隙比e。基于Kramer等给出的膜变形模式,根据板壳理论和弹性力学的基本方程,利用能量守恒定律推导出了考虑初始孔隙比的橡皮膜嵌入量解析解。同时,采用在中三轴试样中埋置不同直径铁棒的方法进行等向固结试验,获得各个围压下粗颗粒土试样的橡皮膜嵌入量。最后,将解析解与试验结果以及前人的解析解进行对比。结果表明,解析解计算得到的膜嵌入量和试验值吻合度较高,验证了所推导解析解的正确性与适用性。

Membrane penetration is the most important factor influencing the measurement of volume change in triaxial consolidated-drained shear test. It has proved that the effective pressure, average particle diameter, thickness of membrane elastic modulus of membrane, contact area between membrane and soil particle and initial void ratio are the major factors influencing membrane penetration. According to the deformation model given by Kramer et al. the analytic solution of the membrane penetration considering the initial void ratio is deduced using the energy conservation law based on the basic equations from theory of plates and shells as well as the elastic mechanics. Membrane penetration volumes are deduced from isotropic consolidation tests by the method of embedding different diameters of iron rods in the triaxial samples. The differences between the analytic solution and test result are analyzed. In general, the results from the analytic solution are considerably agree well with the test data.