沥青混凝土的动水压力模拟试验

Simulation Test of Dynamic Water Pressure for Asphalt Pavement

动水压力模拟试验方法是提高沥青混合料抗水损害性能需要研究的基础理论问题之一。在设计以气压传递激发沥青混凝土孔隙中水压动态变化的试验装置的基础上,通过封闭圆柱形试件的侧壁和在试件底端构造蓄水空间以引导水在孔隙中向下渗流,形成定向冲刷模式。经有限元计算发现随试件深度增加水压减小,说明半刚性基层沥青路面比排水基层沥青路面承受的水压力条件更严酷。应用该试验装置发现动水冲刷使试件劈裂强度逐渐降低;在60℃高温条件下对沥青混凝土进行定向冲刷,出现粉料逸出、试件剪切破坏和破坏面上沥青膜剥落的现象,说明模拟动水压力的破坏作用显著;试验还发现空隙率在8%左右的沥青混合料抗水损害性能最差。该试验方法用于评价沥青混凝土的抗水损害性能是可行的。

The simulation method of dynamic water pressure is one of the basic theories which should be researched to improve the water damage resistance of asphalt mixture. On the basis of designing the test system which generates dynamic water pressure in the voids of asphalt concrete by compressed air, the cylindrical asphalt concrete specimen, which has a space on its bottom and covered with epoxy resin glue on its lateral, was made to induct the water flow oriented through asphalt concrete voids to the established space, thus the oriented water erosion mode was formed. It is found by FEM that （ 1 ） the drainage could reduce the pore pressure in the specimen along its depth, which means pore pressure condition in voids of semi-rigid base asphalt pavement is harsher than that in drainage base asphalt pavement. It is found from the test by this specimen that （ 1 ） the splitting strength of the specimen decreased gradually due to water erosion ; （2） powder escaped from asphalt concrete, shear failure occurred, and asphalt film stripped from the damaged surface during the oriented water erosion to the specimen at 60 ~C, which reveals that the effect of simulated dynamic pore pressure is significant; （3） asphalt mixture with void ratio about 8% has minimum resistance to water damage. These phenomena and test results reveal that the method is feasible for evaluating the water damage resistance of asphalt concrete