Abstract: The effects of confining pressure on mechanical properties of asphalt mixtures are important since the asphalt mixtures in pavement structure behave in a three dimensional stress state.Triaxial dynamic modulus tests were conducted at various temperatures，confi ning pressure levels and frequencies for a Superpave20 mixture with a modified binder and a Superpave25 mixture with a neat binder.The results were analyzed to study the effects of confining pressure on dynamic modulus at various conditions.The analysis results show that the effects of confining pressure on dynamic modulus become more evident as temperature increases and loading frequency decreases.At 55℃ the dynamic moduli obtained at a confining pressure of 250 kPa could be 4.7 and 18 times as high as the values obtained without confining pressure for Superpave 20 and Superpave25，respectively.This study shows that it is important to take the effects of confining pressure into account in pavement structure analysis.

Key words: confining pressure, triaxial dynamic modulus, temperature, loading frequency

摘要： 沥青混合料在路面结构中承受三维应力状态，所以有必要了解其力学性质随围压的变化情况．对改性沥青su— perpave20和普通沥青Superpave25两种混合料分别在不同温度、不同围压和不同频率条件下进行了三轴动态模量试 验，分析了各种条件下围压对动态模量的影响．结果表明，随着温度的升高和荷载频率的降低，NE,对动态模量的影响 越来越显著．当温度<15℃时，围压对动态模量的影响很小，但在55℃时，Superpave20和Superpave25混合料在250kPa 围压时的动态模量可达无围压时的4．7倍和l8倍，表明在进行沥青路面结构分析时很有必要考虑围压的影响．

关键词: 围压, 三轴动态模量, 温度, 荷载频率