To better understand adverse impacts of aging on track maintenance, the hydro-mechanical behavior of unsaturated fresh and aged ballasts was investigated by means of saturated permeability tests, water retention tests, and monotonic loading triaxial compression tests. Firstly, the aged ballast was prepared through the Los Angeles abrasion (LAA) test to reproduce the gradation and particle shape for in-situ aged ballast extracted from actual railway tracks in Japan. Moreover, the results of saturated permeability tests and water retention tests prove that aging induces a remarkable decrease in the saturated coefficient of permeability and a significant increase in water retentivity compared with fresh ballast, due to the presence of fine fraction content. For the shear strength, the effective shear strength parameters of fresh ballast under fully drained conditions (CD test) are close to those under fully undrained conditions (CU test), regardless of water content. However, for the aged ballast, due to the low permeability, it is difficult to simulate fully drained conditions with laboratory tests, even at a very low axial strain rate (0.01%/min). In this case, the effective shear strength parameters of aged ballast are more suitable to be determined by the CU test. Besides, the results of triaxial compression tests prove that aging reduces the effective internal friction angle of ballast, while it increases the total cohesion compared with fresh ballast, especially under the high saturation condition. Lastly, the shear strength of both materials has a decreasing tendency with increasing water content, and the declining trend of shear strength is more noticeable for aged ballast. Therefore, the effects of aging and moisture content on the hydro-mechanical behavior of the railroad ballast should be synergistically considered in the railway track design.

为了更好地了解老化对轨道维护的不利影响，通过饱和渗透性试验，保水试验和单调载荷三轴压缩试验研究了不饱和新鲜和老化压载物的流体力学行为。首先，通过洛杉矶磨蚀（LAA）试验制备了老化的道ast，以再现从日本实际铁路轨道中提取的现场老化的道ast的等级和颗粒形状。此外，饱和渗透性测试和保水测试的结果证明，与新鲜压载相比，老化会导致饱和渗透性系数显着降低，并且保水性显着提高，这归因于存在细碎含量。对于剪切强度，不论含水量如何，在完全排水的条件下（CD试验），新鲜压载物的有效抗剪强度参数都与在完全排水的条件下（CU试验）的有效剪切强度参数相近。但是，对于老化的压载物，由于渗透率低，即使在非常低的轴向应变率（0.01％/ min）下，也难以通过实验室测试模拟完全排水的条件。在这种情况下，老化压载物的有效抗剪强度参数更适合通过CU测试确定。此外，三轴压缩试验的结果证明，与新鲜的镇流器相比，老化降低了镇流器的有效内摩擦角，同时增加了总内聚力，特别是在高饱和条件下。最后，两种材料的剪切强度都随着水含量的增加而降低，老化压载物的抗剪强度下降趋势更为明显。因此，在轨道设计中应协同考虑老化和水分含量对铁路道ball水力学行为的影响。