平面应变试验与常规三轴试验条件下含细粒土砂力学特性比较研究

摘要

In order to understand the mechanical characteristics of the fine-grained sand under an embankment ,the plane strain test and the triaxial test were performed and the results were compared .The comparison results showed that with the same confining pressure , the principal stress difference and generalized shear stress of fine-grained sand by plane strain test were greater than those by triaxial test ,i .e .the strength under the condition of plane strain was larger .Also , it revealed that at the same major main strain ,the maximum value of the generalized shear strain in plane strain test was far greater than that in triaxial test .Compared with the results of triaxial test ,the lateral dilatation of minor main stress was greater ,while the volume strain was much smaller in plane strain test .These fidings indicate that the stress state has great influence on the mechanical characteristics of the fine-grained sand ,and that the mechanical characteristics should be determined by the testing method according to the practical stress state in the engineering .%为获得某堤坝地基下含细粒土砂的力学特性，进行了平面应变试验，并与常规三轴得到的结果进行了对比，结果显示：对于同样围压平面应变试验的偏差应力及广义剪应力大于常规三轴压缩试验，说明平面应变状态下含细粒土砂的强度较高；在相同的大主应变下，平面应变试验的广义剪应变最大值远大于常规三轴试验；同时，也可以看出平面应变试验下，小主应变反映的侧向膨胀更大，而体积应变远小于常规三轴试验。由此说明，应力状态对含细粒土砂的力学特性有重要的影响，应依据工程中实际的受力状态选择相应的试验方法来确定其力学特性。