Creep Characteristics Of Rockfill Materials Experimental Research

Rockfill dam has been widely used by virtue of its advantage,since the 20th century, China has made great achievements in the construction of dam, stabling number of high rockfill dam. Settlement of rockfill dam after completion of the dam will cause internal stress redistribution, which may cause the dam impervious body split, then affect the safe operation of the dam, so rockfill dam design phase must take into account long-term deformation which occur after the completion of the dam. Creep characteristics of rockfill materials is one of the main factors that cause long-term deformation of rockfill dam, while the interior creep test is an important means of research rockfills creep characteristics.The research design three different stress loading models of indoor creep tests, single-stage load creep test, the stress level step by step loading test, stress ratio step by step loading test, to analysis the creep rule and influential factors of rockfill materials and establish rockfills power function creep model by using numerical fitting experimental data. Finally three different stress loading models of creep test were analyzed and compared from a practical point of view the project.The research use SR-4 large high pressure triaxle apparatus for Shangzhai reservoirs and Lianghekou hydropower rockfills indoor creep test. Summing up the results of previous research, the test take the one hour as rockfill materials plastic deformation and creep deformation of the cut-off point, and identified seven days as a creep test trial end criterion.Three different stress loading creep test have similar laws in the total strain and creep, also have differences. Rockfill materials total strain and creep have shown grows as the power function with the increase of time. In double logarithmic coordinates, the creep of rockfill materials and time was a linear relationship.Analysis of single-stage load creep test, the stress level step by step loading test, stress ratio step by step loading test, three creep test results of different load patterns, single-stage load creep test, the partial axial stress is a major factor affecting axial creep and confining pressure is the main factor affecting the volume of creep; the stress level step by step loading test, the axial partial stress is a major factor affecting axial creep as single-stage load creep test and stress levels is the main factor affecting the volume of creep, analyze the reasons is the impact of rockfills dilatancy and loading style; stress ratio step by step loading test, partial axial stress is a major factor affecting the axial creep and confining pressure is the main factor affecting the volume of creep.Finally, from an engineering point of view, stress ratio step by step loading is more fitting rockfill dam construction process. The axial partial stress is a major factor affecting rockfills axial creep and confining pressure caused rockfills volume creep factors. Three different loading also shows that the loading stress paths have a significant impact on the creep characteristics of rockfill materials and require further study.