Study On Dynamic Properties Of Core Material And Dam-Foundation Fine Gravel Of Earth-Rock Dam

Earth-rock dam is widely adopted at home and abroad because of locally-produced raw materials and simple construction. China is one of the countries in the world whose earthquake disasters are very serious. If earth-rock dams suffer from earthquake, serious results would arise. At present earth-rock dams located at seismic area are all dynamically analyzed during earthquake resistance design. Credible dynamic parameters of dam materials obtained from indoor tests are the key to the accuracy of dynamical analysis for earth-rock dam.Field basic earthquake intensity of Shuiniujia core earth-rock dam is eight and its fortify intensity is nine. Through the cyclic triaxial instrument, tests of dynamic modulus, damping ratio and dynamic strength of core material and dam-foundation fine gravel were performed. Dynamical strength and parameters were ensured and some affecting factors were discussed.Cyclic stress ratio "R? of core material is lower than those of other core earth-rock dams, so its compaction degree should be guaranteed. For core material, in spite of equivalent-pressure or unequivalent-pressure consolidation, liquefaction phenomenon wouldn't appear. "R,," of dam-foundation fine gravel is obviously higher than those of ordinary sands. When consolidated stress ratio "Kc" equals to 0.7 ~ 1.3, final porewater pressure could all reach confining pressure; when "Kc" exceeds or equals to 1.5, whether samples could liquefy lie on that dynamic stress "a d" could make samples stretch or not. Confining pressure has little effect on "R?. Sample dynamic strength increases with the increasing of "Kc", but at a certain value of "Kc", dynamic strength tends to decrease. When vibration frequency "f equals to 0.1~4Hz, dynamic strength of core material increases with "f'. Dynamic porewater pressure ratio of core material increases during f equals to 0.1~1.0Hz and decreases during f equals to 1.0~6.0Hz with the increasing of "f.Among many factors affecting dynamic modulus "Ed" and damping ratio "D", dynamic strain level is primary. "Ed" decreases and "D" increases very rapidly with strain level. Both "Ed" and "D" increases with consolidated stress ratio and vibration frequency. And "Ed" increases while "D" decreases with confining pressure. The lower the vibration frequency acting on the sample, the more sufficient dynamic deformation could develop.