土样回弹及再压缩变形特征的试验研究

通过固结回弹试验对土体的回弹变形规律进行研究,提出回弹比率的概念,更为清晰地反映出了回弹变形随卸荷比变化的发展过程:当卸荷比小于0.4时,土样卸荷产生的回弹量不到总回弹量的10%;而当卸荷比在0.9～1.0之间时,土样卸荷产生的回弹量占到总回弹量的40%～60%。将原有的卸荷比—回弹模量分析方法中的R-Ec与R-lgEc方法相结合应用,得出土体回弹变形发展的3个阶段,为回弹变形的计算提供参考,同时通过对卸荷比—回弹模量关系曲线进行拟合分析,可得到在任一卸荷比下土体的回弹模量。试验结果表明:土体回弹率与固结压力、卸荷比密切相关,反映了土体回弹变形的基本特征;在土样的再压缩过程中,再压缩变形大于回弹变形。结合模型试验实测结果,对土样的再压缩变形进行了研究。

Experimental study on the characteristics of the rebound and the recompression deformation of soil under unloading

The soil rebound deformation is studied through the soil consolidation-rebound tests.The new parameter-rebound rate for rebound deformation provides a new effective method to analyze the development of rebound deformation with the change of unloading ratio.When the unloading ratio is lower than 0.4,the rebound deformation is less than 10% of the total rebound deformation,however,when the unloading ratio is between 0.9 and 1.0,the rebound deformation is up to 40% ～ 60% of the total rebound deformation.With the combination of the R-Ec and the R-lgEc in the original unloading ratio-rebound modulus analysis methods,the three development phases of rebound deformation could be as the reference for the calculation,furthermore,the function fitting method is used to analyze the relationship between unloading ratio and rebound modulus,and then the rebound modulus at any unloading ratio could be calculated by this method.There are close relationship between the rebound ratio and the consolidated stress,unloading ratio,which indicate the basic characteristics of rebound deformation.In the process of soil recompression,the recompression deformation is greater than the rebound deformation.Compared with the results from model tests the recompression deformation of soil samples is studied.